Biomarkers in the cerebrospinal fluid of patients with psychotic disorders compared to healthy controls: a systematic review and meta-analysis

Psychotic disorders are severe mental disorders with poorly understood etiology. Biomarkers in the cerebrospinal fluid (CSF) could provide etiological clues and diagnostic tools for psychosis; however, an unbiased overview of CSF alterations in individuals with psychotic disorders is lacking. The objective of this study was to summarize all quantifiable findings in CSF from individuals with psychotic disorders compared to healthy controls (HC). Studies published before January 25th, 2023 were identified searching PubMed, EMBASE, Cochrane Library, Web of Science, ClinicalTrials.gov, and PsycINFO. Screening, full-text review, data extraction, and risk of bias assessments were performed by two independent reviewers following PRISMA guidelines. Findings in patients and healthy controls were compared and summarized using random-effects analyses and assessment of publication bias, subgroup and sensitivity analyses were performed. 145 studies, covering 197 biomarkers, were included, of which 163 biomarkers have not previously been investigated in meta-analyses. All studies showed some degree of bias. 55 biomarkers measured in CSF were associated with psychosis and of these were 15 biomarkers measured in ≥2 studies. Patients showed increased levels of noradrenaline (standardized mean difference/SMD, 0.53; 95% confidence interval/CI, 0.16 to 0.90) and its metabolite 3-methoxy-4-hydroxyphenylglycol (SMD, 0.30; 95% CI: 0.05 to 0.55), the serotonin metabolite 5-hydroxyindoleacetic acid (SMD, 0.11; 95% CI: 0.01 to 0.21), the pro-inflammatory neurotransmitter kynurenic acid (SMD, 1.58; 95% CI: 0.34 to 2.81), its precursor kynurenine (SMD,0.99; 95% CI: 0.60 to 1.38), the cytokines interleukin-6 (SMD, 0.58; 95% CI: 0.39 to 0.77) and interleukin-8 (SMD, 0.43; 95% CI: 0.24 to 0.62), the endocannabinoid anandamide (SMD, 0.78; 95% CI: 0.53 to 1.02), albumin ratio (SMD, 0.40; 95% CI: 0.08 to 0.72), total protein (SMD, 0.29; 95% CI: 0.16 to 0.43), immunoglobulin ratio (SMD, 0.45; 95% CI: 0.06 to 0.85) and glucose (SMD, 0.48; 95% CI: 0.01 to 0.94). Neurotensin (SMD, -0.67; 95% CI: -0.89 to -0.46) and γ-aminobutyric acid (SMD, -0.29; 95% CI: -0.50 to -0.09) were decreased. Most biomarkers showed no significant differences, including the dopamine metabolites homovanillic acid and 3,4-dihydroxyphenylacetic acid. These findings suggest that dysregulation of the immune and adrenergic system as well as blood-brain barrier dysfunction are implicated in the pathophysiology of psychotic disorders.

Cerebrospinal Fluid Pterins, Pterin-Dependent Neurotransmitters, and Mortality in Pediatric Cerebral Malaria

BACKGROUND

Cerebral malaria (CM) pathogenesis remains incompletely understood. Having shown low systemic levels of tetrahydrobiopterin (BH4), an enzymatic cofactor for neurotransmitter synthesis, we hypothesized that BH4 and BH4-dependent neurotransmitters would likewise be low in cerebrospinal fluid (CSF) in CM.

METHODS

We prospectively enrolled Tanzanian children with CM and children with nonmalaria central nervous system conditions (NMCs). We measured CSF levels of BH4, neopterin, and BH4-dependent neurotransmitter metabolites, 3-O-methyldopa, homovanillic acid, and 5-hydroxyindoleacetate, and we derived age-adjusted z-scores using published reference ranges.

RESULTS

Cerebrospinal fluid BH4 was elevated in CM (n = 49) compared with NMC (n = 51) (z-score 0.75 vs -0.08; P < .001). Neopterin was increased in CM (z-score 4.05 vs 0.09; P < .001), and a cutoff at the upper limit of normal (60 nmol/L) was 100% sensitive for CM. Neurotransmitter metabolite levels were overall preserved. A higher CSF BH4/BH2 ratio was associated with increased odds of survival (odds ratio, 2.94; 95% confidence interval, 1.03-8.33; P = .043).

CONCLUSION

Despite low systemic BH4, CSF BH4 was elevated and associated with increased odds of survival in CM. Coma in malaria is not explained by deficiency of BH4-dependent neurotransmitters. Elevated CSF neopterin was 100% sensitive for CM diagnosis and warrants further assessment of its clinical utility for ruling out CM in malaria-endemic areas.

Retrospective analysis of 19 patients with 6-Pyruvoyl Tetrahydropterin Synthase Deficiency: Prolactin levels inversely correlate with growth

BACKGROUND

Pyruvoyl Tetrahydropterin Synthase (PTPS) Deficiency is the most common form of BH4 deficiency resulting in hyperphenylalaninemia. It can have variable clinical severity and there is limited information on the clinical presentation, natural history and effectiveness of newborn screening for this condition.

METHODS

Retrospective data (growth and clinical parameters, biochemical and genetic testing results, treatment) were collected from 19 patients with PTPS deficiency in different centers, to evaluate biochemical and clinical outcomes. Descriptive statistics was used for qualitative variables, while linear regression analysis was used to correlate quantitative variables.

RESULTS

Patients with PTPS deficiency had an increased incidence of prematurity (4/18) with an average gestational age only mildly reduced (37.8 ± 2.4 weeks) and low birth weight (-1.14 ± 0.97 SD below that predicted for gestational age). With time, weight and height approached normal.

VALUES

All patients were identified by newborn screening for an elevated phenylalanine level. However, phenylalanine levels were normal in two whose testing was performed at or before 24 h of age. Sapropterin dihydrochloride treatment normalized phenylalanine levels. Molecular testing identified novel variants in the PTS gene, some of which present in more than one affected family. The neurotransmitter derivatives 5-hydroxyindoleacetic acid (5HIAA) and homovanillic acid (HVA) in the CSF were decreased in most cases except in 2 families with the peripheral form of PTPS deficiency. With time, HVA and 5HIAA became abnormally low in two of these patients requiring therapy. Prolactin (whose secretion is inhibited by dopamine) levels were elevated in several patients with PTPS deficiency and inversely correlated with the z-scores for height (p < 0.01) and weight (p < 0.05). Most patients with PTPS deficiency had delayed development early in life, improving around school age with IQs mostly in the normal range, with a small decline in older individuals. From a neurological standpoint, most patients had normal brain MRI and minor EEG anomalies, although some had persistent neurological symptoms.

DISCUSSION

Patients with PTPS deficiency have not only an increased incidence of prematurity, but also decreased birth weight when corrected for gestational age. Hyperphenylalaninemia can be absent in the first day of life. Therapy with sapropterin dihydrochloride normalizes phenylalanine levels and neurotransmitter precursors can improve CSF neurotransmitter metabolites levels. Insufficient dopaminergic stimulation (as seen from elevated prolactin) might result in decreased height in patients with PTPS deficiency. Despite early delays in development, many patients can achieve independence in adult life, with usually normal neuroimaging and EEG.

Long-term clinical outcome of 6-pyruvoyl-tetrahydropterin synthase-deficient patients

INTRODUCTION

6-Pyruvoyl-tetrahydropterin synthase deficiency (PTPSd) is a rare autosomal recessive disorder of synthesis of biogenic amines, which is characterized by variable neurological impairment and hyperphenylalaninemia. We aimed to assess the long-term clinical outcome of this disorder and the factors affecting it.

METHODS

At total of 28 PTPSd patients (aged 19.9 ± 10.9 years) underwent clinical (neurological and psychiatric) and neuropsychological assessment (BRIEF, VABS-II, and IQ). Based on CSF homovanillic (HVA) and 5-hydroxyindolacetic acid (5-HIAA) and pterin concentrations at diagnosis, patients were classified as having either a severe [SF; low level of CSF, HVA, and 5-HIAA with altered neopterin/biopterin (Neo/Bio)] or mild form (MF; normal HVA and 5-HIAA with altered Neo/Bio) of PTPSd.

RESULTS

Approximately 36% of patients had MF PTPSd. At the last examination, 43% of patients had movement disorders (2 MF, 10 SF), 43% of patients had variable degrees of intellectual disability (SF only), 39% met the criteria for a psychiatric disorder (3 MF, 9 SF). Applying a linear regression model, we found that HVA and phenylalanine levels at birth had a significant influence on IQ, BRIEF, and VABS-II variability. Lastly, 5-HIAA further contributed to VABS-II variability. The disease showed a self-limiting clinical course and its treatment, although delayed, is effective in improving the neurological status.

CONCLUSIONS

Neurodevelopmental impairment due to PTPSd shows a self-limiting course. A continuous improvement in the neurological condition has been observed in patients receiving treatment, even when delayed. The severity of brain biogenic amine depletion at diagnosis predicts neurological and psychiatric outcomes.

Cerebrospinal fluid biogenic amines depletion and brain atrophy in adult patients with phenylketonuria

Biogenic amines synthesis in phenylketonuria (PKU) patients with high phenylalanine (Phe) concentration is thought to be impaired due to inhibition of tyrosine and tryptophan hydroxylases and competition with amino acids at the blood-brain barrier. Dopamine and serotonin deficits might explain brain damage and progressive neuropsychiatric impairment in adult PKU patients. Ten early treated adult PKU patients (mean age 38.2 years) and 15 age-matched controls entered the study. Plasma and cerebrospinal fluid (CSF) Phe, 5-hydroxyindoleacetic acid (5-HIAA), 5-hydroxytryptophan (5-HTP), 3,4-dihydroxy-l-phenylalanine (l-DOPA) and homovanillic acid (HVA) were analyzed. Voxel-based morphometry statistical nonparametric mapping was used to test the age-corrected correlation between gray matter atrophy and CSF biogenic amines levels. 5-HIAA and 5-HTP were significantly reduced in PKU patients compared to controls. Significant negative correlations were found between CSF 5-HIAA, HVA, and 5-HTP and Phe levels. A decrease in 5-HIAA and 5-HTP concentrations correlated with precuneus and frontal atrophy, respectively. Lower HVA levels correlated with occipital atrophy. Biogenic amines deficits correlate with specific brain atrophy patterns in adult PKU patients, in line with serotonin and dopamine projections. These findings may support a more rigorous Phe control in adult PKU to prevent neurotransmitter depletion and accelerated brain damage due to aging.

Pharmacokinetics and pharmacodynamics of a single dose Nilotinib in individuals with Parkinson's disease

Nilotinib is a broad-based tyrosine kinase inhibitor with the highest affinity to inhibit Abelson (c-Abl) and discoidin domain receptors (DDR1/2). Preclinical evidence indicates that Nilotinib reduces the level of brain alpha-synuclein and attenuates inflammation in models of Parkinson's disease (PD). We previously showed that Nilotinib penetrates the blood-brain barrier (BBB) and potentially improves clinical outcomes in individuals with PD and dementia with Lewy bodies (DLB). We performed a physiologically based population pharmacokinetic/pharmacodynamic (popPK/PD) study to determine the effects of Nilotinib in a cohort of 75 PD participants. Participants were randomized (1:1:1:1:1) into five groups (n = 15) and received open-label random single dose (RSD) 150:200:300:400 mg Nilotinib vs placebo. Plasma and cerebrospinal fluid (CSF) were collected at 1, 2, 3, and 4 hours after Nilotinib administration. The results show that Nilotinib enters the brain in a dose-independent manner and 200 mg Nilotinib increases the level of 3,4-Dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), suggesting alteration to dopamine metabolism. Nilotinib significantly reduces plasma total alpha-synuclein and appears to reduce CSF oligomeric: total alpha-synuclein ratio. Furthermore, Nilotinib significantly increases the CSF level of triggering receptors on myeloid cells (TREM)-2, suggesting an anti-inflammatory effect. Taken together, 200 mg Nilotinib appears to be an optimal single dose that concurrently reduces inflammation and engages surrogate disease biomarkers, including dopamine metabolism and alpha-synuclein.

Preliminary validation of natural depression in macaques with acute treatments of the fast-acting antidepressant ketamine

Non-human primates have become one of the most important model animals for the investigation of brain diseases because they share a wide-range of genetics and social similarities with human beings. Naturally-evoked depression models in macaques may offer a full spectrum of similarity to human depression states, but they require validation and corroboration of specific phenotypes to depression-associated states before they can be used in research into more effective interventions. It is reported here that depressed cynomolgus monkeys developed in the natural condition display higher levels of typical depressive-like huddling behavior than healthy monkeys. Moreover, these depressed macaques presented other key phenotypes linked to depression, including low levels of cerebrospinal fluid monoamine neurotransmitters and their metabolites, increased passive states, reduced positive behaviors and disrupted nocturnal sleep. When subjected to an acute subanesthetic dose of ketamine, the depressed monkeys responded substantially in rapid and sustained antidepressant-like ways, which demonstrated decreased huddling behavior, an elevated interest in exploration activities and sleep improvement. Taken together, this naturally-evoked depression monkey model was systematically validated for ecological, face, construct and predictive validities. This model will serve as a qualified platform for studying depression in the future.

Cerebrospinal fluid monoamines, pterins, and folate in patients with mitochondrial diseases: systematic review and hospital experience

Mitochondrial diseases are a group of genetic disorders leading to the dysfunction of mitochondrial energy metabolism pathways. We aimed to assess the clinical phenotype and the biochemical cerebrospinal fluid (CSF) biogenic amine profiles of patients with different diagnoses of genetic mitochondrial diseases. We recruited 29 patients with genetically confirmed mitochondrial diseases harboring mutations in either nuclear or mitochondrial DNA (mtDNA) genes. Signs and symptoms of impaired neurotransmission and neuroradiological data were recorded. CSF monoamines, pterins, and 5-methyltetrahydrofolate (5MTHF) concentrations were analyzed using high-performance liquid chromatography with electrochemical and fluorescence detection procedures. The mtDNA mutations were studied by Sanger sequencing, Southern blot, and real-time PCR, and nuclear DNA was assessed either by Sanger or next-generation sequencing. Five out of 29 cases showed predominant dopaminergic signs not attributable to basal ganglia involvement, harboring mutations in different nuclear genes. A chi-square test showed a statistically significant association between high homovanillic acid (HVA) values and low CSF 5-MTHF values (chi-square = 10.916; p = 0.001). Seven out of the eight patients with high CSF HVA values showed cerebral folate deficiency. Five of them harbored mtDNA deletions associated with Kearns-Sayre syndrome (KSS), one had a mitochondrial point mutation at the mtDNA ATPase6 gene, and one had a POLG mutation. In conclusion, dopamine deficiency clinical signs were present in some patients with mitochondrial diseases with different genetic backgrounds. High CSF HVA values, together with a severe cerebral folate deficiency, were observed in KSS patients and in other mtDNA mutation syndromes.

Spectrum of movement disorders and neurotransmitter abnormalities in paediatric POLG disease

OBJECTIVES

To describe the spectrum of movement disorders and cerebrospinal fluid (CSF) neurotransmitter profiles in paediatric patients with POLG disease.

METHODS

We identified children with genetically confirmed POLG disease, in whom CSF neurotransmitter analysis had been undertaken. Clinical data were collected retrospectively. CSF neurotransmitter levels were compared to both standardised age-related reference ranges and to non-POLG patients presenting with status epilepticus.

RESULTS

Forty-one patients with POLG disease were identified. Almost 50% of the patients had documented evidence of a movement disorder, including non-epileptic myoclonus, choreoathetosis and ataxia. CSF neurotransmitter analysis was undertaken in 15 cases and abnormalities were seen in the majority (87%) of cases tested. In many patients, distinctive patterns were evident, including raised neopterin, homovanillic acid and 5-hydroxyindoleacetic acid levels.

CONCLUSIONS

Children with POLG mutations can manifest with a wide spectrum of abnormal movements, which are often prominent features of the clinical syndrome. Underlying pathophysiology is probably multifactorial, and aberrant monoamine metabolism is likely to play a role.

Biomarkers in cerebrospinal fluid of patients with bipolar disorder versus healthy individuals: A systematic review

BACKGROUND

The pathophysiological processes of bipolar disorder (BD) may be detectable by the use of cerebrospinal fluid (CSF) biomarkers.

AIM

We aimed for the first time to review studies of CSF biomarkers in patients with BD compared to healthy control individuals (HC). We investigated the effect of diagnosis, age, gender, clinical state, medication, technical characteristics of tests, fasting state and, cognitive function if applicable.

METHOD

We did a systematic review according to the PRISMA Statement based on comprehensive database searches for studies on cerebrospinal biomarkers in patients with bipolar disorder versus HC. Risk of bias was systematically assessed.

RESULTS

The search strategy identified 410 studies of which thirty-four fulfilled the inclusion criteria. A total of 117 unique biomarkers were investigated, out of which 11 were evaluated in more than one study. Forty biomarkers showed statistically significant differences between BD and HC in single studies. Only the findings of elevated homovanillic acid and 5-hydroxy-indoleacetic acid were replicated across studies. Most studies had a cross sectional design and were influenced by risk of bias mainly due to small sample size, lack of data on mood state at the time of the CSF puncture and not considering potential confounders including age, gender, diagnoses, BMI, life style factors such as smoking, and psychotropic medication.

CONCLUSION

Specific monoamine CSF biomarkers may be related to the pathophysiology of BD. Future studies must aim at increasing the level of evidence by validating the positive findings in prospective studies with stringent methodology.

Secondary neurotransmitter deficiencies in epilepsy caused by voltage-gated sodium channelopathies: A potential treatment target?

We describe neurotransmitter abnormalities in two patients with drug-resistant epilepsy resulting from deleterious de novo mutations in sodium channel genes. Whole exome sequencing identified a de novo SCN2A splice-site mutation (c.2379+1G>A, p.Glu717Gly.fs*30) resulting in deletion of exon 14, in a 10-year old male with early onset global developmental delay, intermittent ataxia, autism, hypotonia, epileptic encephalopathy and cerebral/cerebellar atrophy. In the cerebrospinal fluid both homovanillic acid and 5-hydroxyindoleacetic acid were significantly decreased; extensive biochemical and genetic investigations ruled out primary neurotransmitter deficiencies and other known inborn errors of metabolism. In an 8-year old female with an early onset intractable epileptic encephalopathy, developmental regression, and progressive cerebellar atrophy, a previously unreported de novo missense mutation was identified in SCN8A (c.5615G>A; p.Arg1872Gln), affecting a highly conserved residue located in the C-terminal of the Nav1.6 protein. Aside from decreased homovanillic acid and 5-hydroxyindoleacetic acid, 5-methyltetrahydrofolate was also found to be low. We hypothesize that these channelopathies cause abnormal synaptic mono-amine metabolite secretion/uptake via impaired vesicular release and imbalance in electrochemical ion gradients, which in turn aggravate the seizures. Treatment with oral 5-hydroxytryptophan, l-Dopa/Carbidopa, and a dopa agonist resulted in mild improvement of seizure control in the male case, most likely via dopamine and serotonin receptor activated signal transduction and modulation of glutamatergic, GABA-ergic and glycinergic neurotransmission. Neurotransmitter analysis in other sodium channelopathy patients will help validate our findings, potentially yielding novel treatment opportunities.

Decreased cerebral spinal fluid neurotransmitter levels in Smith-Lemli-Opitz syndrome

Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessive, multiple congenital anomaly syndrome with cognitive impairment and a distinct behavioral phenotype that includes autistic features. SLOS is caused by a defect in 3β-hydroxysterol Δ(7)-reductase which leads to decreased cholesterol levels and elevated cholesterol precursors, specifically 7- and 8-dehydrocholesterol. However, the pathological processes contributing to the neurological abnormalities in SLOS have not been defined. In view of prior data suggesting defects in SLOS in vesicular release and given the association of altered serotonin metabolism with autism, we were interested in measuring neurotransmitter metabolite levels in SLOS to assess their potential to be used as biomarkers in therapeutic trials. We measured cerebral spinal fluid levels of serotonin and dopamine metabolites, 5-hydroxyindoleacetic acid (5HIAA) and homovanillic acid (HVA) respectively, in 21 SLOS subjects. Results were correlated with the SLOS anatomical severity score, Aberrant Behavior Checklist scores and concurrent sterol biochemistry. Cerebral spinal fluid (CSF) levels of both 5HIAA and HVA were significantly reduced in SLOS subjects. In individual patients, the levels of both 5HIAA and HVA were reduced to a similar degree. CSF neurotransmitter metabolite levels did not correlate with either CSF sterols or behavioral measures. This is the first study demonstrating decreased levels of CSF neurotransmitter metabolites in SLOS. We propose that decreased levels of neurotransmitters in SLOS are caused by a sterol-related defect in synaptic vesicle formation and that CSF 5HIAA and HVA will be useful biomarkers in development of future therapeutic trials.

Elevated CSF serotonin and dopamine metabolite levels in overweight subjects

OBJECTIVE

Neurotransmitter systems participate in the regulation of food intake, and their activities are expected to influence eating behavior.

DESIGN AND METHODS

We investigated possible associations between body mass index (BMI) and central noradrenaline, serotonin, and dopamine activities, as reflected by the cerebrospinal fluid levels of their main metabolites methoxyhydroxyphenylglycol (MHPG), 5-hydroxyindoleacetic acid (5-HIAA), and homovanillic acid (HVA), respectively. We studied 192 subjects (111 males, 81 females) admitted to neurologic clinic for diagnostic investigations that included CSF analysis, and were found not to suffer from any major neurological disease. Subjects were categorized in three groups, namely in lower, in the two middle, and in upper BMI quartiles, the limits calculated separately for males and females.

RESULTS

No differences were found in MHPG levels between groups, while subjects in the upper BMI quartile showed significantly elevated levels of 5-HIAA and HVA compared to the levels of subjects in lower and middle quartiles.

CONCLUSIONS

The results provide evidence that in overweight subjects there are enhanced demands in serotoninergic and dopaminergic signaling for their reward system that may lead to increased motivation for food consumption. The implication of reward centers in eating behavior supports the hypothesis of common mechanisms in obesity and drug addiction.

Social dominance in female monkeys: dopamine receptor function and cocaine reinforcement

BACKGROUND

Brain imaging and behavioral studies suggest an inverse relationship between dopamine (DA) D2/D3 receptors and vulnerability to cocaine abuse, although most research has used males. For example, male monkeys that become dominant in a social group have significant elevations in D2/D3 receptor availability and are less vulnerable to cocaine reinforcement.

METHODS

DA D2/D3 receptor availability was assessed in female cynomolgus monkeys (n = 16) with positron emission tomography (PET) while they were individually housed, 3 months after stable social hierarchies had formed, and again when individually housed. In addition, PET was used to examine changes in dopamine transporter (DAT) availability after social hierarchy formation. After imaging studies were complete, monkeys received implantation with indwelling intravenous catheters and self-administered cocaine (.001-.1 mg/kg/injection) under a fixed-ratio 30 schedule of reinforcement. Acquisition of cocaine reinforcement occurred when response rates were significantly higher than when saline was self-administered.

RESULTS

Neither DAT nor D2/D3 receptor availability in the caudate nucleus and putamen was predictive of social rank, but both significantly changed after formation of social hierarchies. DA D2/D3 receptor availability significantly increased in females that became dominant, whereas DAT availability decreased in subordinate females. Dominant female monkeys acquired cocaine reinforcement at significantly lower doses than subordinate monkeys.

CONCLUSIONS

The relationship between D2/D3 receptor availability and vulnerability to cocaine reinforcement seems, on the basis of these findings, opposite in females and males. These data indicate that the social environment profoundly affects the DA system but does so in ways that have different functional consequences for females than for males.

[The HPLC analysis of vanillil-almond, 5-hydroxiindolacetic, homovanillic and homogentisic acids in biologic fluids in clinical laboratory]

The simple and fast HPLC technique of analysis of vanillil-almond, 5-hydroxiindolacetic, homovanillic and homogentisic acids in urine with solid-phase extraction using ultra cross-linked polystyrene (Purosep-200) is proposed. The separation on column Chromolith Performance RP-18e "Merck" 100x4.6 mm with monolithic phase-reversed silica gel in isocratic or gradient mode with ultraviolet detection under 285 nm. The isocratic mode is applied in case of ordinary analysis of vanillil-almond or homogentisic acids. The composition of eluent is isopropanol - water - TFA (1:99:0.025, v/v/v), flow speed is 1400 mkl/min; pressure is 37 bar, full separation less than in 4 min. The gradient low pressure mode is applied to analyze vanillil-almond, hydroxiindolacetic and homovanillic acids. Under this approach the switching to second eluent occurred from second minute. The composition of eluent is isopropanol-water-TFA (6:94:0.025, v/v/v), flow speed is 1400 mkl/min, pressure is 43 bar, full separation is less than in 7 min. The output (extraction share) consisted 78-113%. The simplicity reproducibility and sufficient sensitivity of technique in combination with the possibility of its application on standard chromatographic equipment (isocratic pump and ultraviolet detector) made it useful for routine clinical application.

Dystrobrevin-binding protein 1 gene (DTNBP1) variants associated with cerebrospinal fluid homovanillic acid and 5-hydroxyindoleacetic acid concentrations in healthy volunteers

The dystrobrevin binding protein-1 (DTNBP1) gene encodes dysbindin-1, a protein involved in neurodevelopmental and neurochemical processes related mainly to the monoamine dopamine. We investigated possible associations between eleven DTNBP1 polymorphisms and cerebrospinal fluid (CSF) concentrations of the major dopamine metabolite homovanillic acid (HVA), the major serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA), and the major noradrenaline metabolite 3-methoxy-4-hydroxyphenylglycol (MHPG) in healthy human subjects (n=132). Two polymorphisms, rs2619538 and rs760666, were nominally associated with CSF HVA and 5-HIAA concentrations, whereas a third polymorphism, rs909706, showed association only with HVA. After correction for multiple testing only the associations between rs2619538 and HVA and 5-HIAA concentrations remained significant. No significant association was found between any of the investigated DTNBP1 polymorphisms and CSF MHPG concentrations. The results suggest that genetic variation in DTNBP1 gene affects the regulation of dopamine and serotonin turnover in the central nervous system of healthy volunteers.

CSF xanthine, homovanillic acid, and their ratio as biomarkers of Parkinson's disease

Diminished nigrostriatal dopaminergic neurotransmission is a biochemical hallmark of Parkinson's disease. Despite this, a reliable trait biomarker of sporadic Parkinson's disease has not emerged from measurements of cerebrospinal fluid dopamine metabolites. Previous studies have highlighted strong neurochemical relationships between dopamine and various purine compounds. In this study, we analyzed cerebrospinal fluid concentrations of homovanillic acid (the major catabolite of dopamine) and the purine compound xanthine for a comparison of 217 unmedicated Parkinson's disease subjects and 26 healthy controls. These compounds were highly correlated for both the Parkinson's disease subjects (r=0.68) and for controls (r=0.73; both groups, p<0.001). While neither homovanillic acid nor xanthine concentrations differentiated Parkinson's disease from controls, their ratio did. For controls, the mean [xanthine]/[homovanillic acid] quotient was 13.1±5.5 as compared to the Parkinson's disease value of 17.4±6.7 at an initial lumbar CSF collection (p=0.0017), and 19.7±8.7 (p<0.001) at a second CSF collection up to 24 months later. The [xanthine]/[homovanillic acid] ratio in the Parkinson's disease subjects differed as a function of disease severity, as measured by the sum of Unified Parkinson's Disease Rating Scale Activities of Daily Living and Motor Exam ratings. The [xanthine]/[homovanillic acid] ratio also increased between the first and second CSF collections, suggesting that this quotient provides both a state and trait biomarker of Parkinson's disease. These observations add to other neurochemical evidence that links purine metabolism to Parkinson's disease.

Behavioral characterization of adult male and female rhesus monkeys exposed to cocaine throughout gestation

RATIONALE

In utero cocaine exposure has been associated with alterations in the dopamine (DA) system in monkeys. However, the behavioral outcomes of prenatal cocaine exposure in adulthood are poorly understood.

OBJECTIVES

To assess several behavioral measures in 14-year-old rhesus monkeys exposed to cocaine in utero and controls (n = 10 per group).

MATERIALS AND METHODS

For these studies, two unconditioned behavioral tasks, novel object reactivity and locomotor activity, and two conditioned behavioral tasks, response extinction and delay discounting, were examined. In addition, cerebrospinal fluid (CSF) samples were analyzed for concentrations of the monoamine metabolites homovanillic acid (HVA) and 5-hydroxyindole acetic acid (5-HIAA).

RESULTS

No differences in CSF concentrations of 5-HIAA and HVA, latencies to touch a novel object or locomotor activity measures were observed between groups or sexes. However, prenatally cocaine-exposed monkeys required a significantly greater number of sessions to reach criteria for extinction of food-reinforced behavior than control monkeys. On the delay-discounting task, male prenatally cocaine-exposed monkeys switched preference from the larger reinforcer to the smaller one at shorter delay values than male control monkeys; no differences were observed in females.

CONCLUSIONS

These findings suggest that prenatal cocaine exposure results in long-term neurobehavioral deficits that are influenced by sex of the individual.

Cerebrospinal fluid metabolite and nigrostriatal dopaminergic function in Parkinson's disease

OBJECTIVES

To evaluate the association between cerebrospinal fluid (CSF) homovanillic acid (HVA) concentrations and nigrostriatal dopaminergic function assessed by positron emission tomography (PET) imaging with carbon-11-labeled 2beta-carbomethoxy-3beta-(4-fluorophenyl)-tropane ((11)C-CFT), which can measure the dopamine transporter (DAT) density, in Parkinson's disease (PD).

METHODS

(11)C-CFT PET scans and CSF examinations were performed on 21 patients with PD, and six patients with non-parkinsonian syndromes (NPS) as a control group.

RESULTS

In the PD group, CSF HVA concentrations were significantly correlated with the striatal uptake of (11)C-CFT (r = 0.76, P < 0.01). However, in the NPS group, two indices were within the normal range.

CONCLUSIONS

In PD, CSF HVA concentrations correlate with nigrostriatal dopaminergic function. Therefore, CSF HVA concentrations may be an additional surrogate marker for estimating the remaining nigrostriatal dopaminergic function in case that DAT imaging is unavailable.

Monoamines, BDNF, IL-6 and corticosterone in CSF in patients with Parkinson's disease and major depression

The biochemical basis of major depression (MD) in Parkinson's disease (PD) is largely unknown. To increase our understanding of MD in PD patients, the levels of monoamine metabolites (HVA, 5-HIAA and MHPG), BDNF, orexin-A, IL-6 and corticosterone were examined in cerebrospinal fluid. The analyses were performed in MD patients with (n = 11) and without (n = 12) PD at baseline and after 12 weeks' of treatment with the antidepressant citalopram, and in patients with solely PD (n = 14) at baseline and after 12 weeks. The major findings were that PD patients with MD had significantly lower baseline levels of MHPG, corticosterone and IL-6 when compared to patients with solely MD. In response to citalopram treatment, patients with solely MD exhibited an expected decrease in 5-HIAA and MHPG levels which was not found in PD patients with MD. Moreover, the levels of BDNF and IL-6 were lower in PD patients with MD compared with patients with solely MD after treatment with citalopram. Thus, the biochemical basis and the response to citalopram differ between PD patients with MD and patients with solely MD.

Mother-infant interactions in free-ranging rhesus macaques: relationships between physiological and behavioral variables

Studies of mother-infant relationships in nonhuman primates have increasingly attempted to understand the neuroendocrine bases of interindividual variation in mothering styles and the mechanisms through which early exposure to variable mothering styles affects infant behavioral development. In this study of free-ranging rhesus macaques on Cayo Santiago, Puerto Rico, we aimed to: 1) compare lactating and nonlactating females to investigate whether lactation is associated with changes in plasma cortisol, prolactin and oxytocin, as well as changes in CSF levels of serotonin and dopamine metabolites (5-HIAA and HVA); 2) examine the extent to which interindividual variation in maternal physiology is associated with variation in maternal behavior; 3) examine the extent to which interindividual variation in infant physiology and behavior is accounted for by variation in maternal physiology and behavior. Lactating females had higher plasma concentrations of cortisol, prolactin, and oxytocin but lower CSF concentrations of HVA than nonlactating females. Variation in maternal rejection behavior was positively correlated with variation in maternal plasma cortisol levels and in CSF 5-HIAA levels while variation in the time spent nursing and grooming was associated with maternal plasma oxytocin levels. Infants who were protected more by their mothers had higher cortisol levels than those who were protected less, while infants who were rejected more had lower CSF 5-HIAA than infants who were rejected less. Since exposure to high levels of maternal protectiveness and rejection is known to affect the offspring's behavior and responsiveness to the environment later in life, our results are consistent with the hypothesis that these effects are mediated by long-term changes in the activity of the offspring's HPA axis and brain serotonergic system.

Norman Cousins Lecture. Mechanisms of cytokine-induced behavioral changes: psychoneuroimmunology at the translational interface

Work in our laboratory has focused on the mechanisms by which cytokines can influence the brain and behavior in humans and non-human primates. Using administration of interferon (IFN)-alpha as a tool to unravel these mechanisms, we have expanded upon findings from the basic science literature implicating cytokine-induced changes in monoamine metabolism as a primary pathway to depression. More specifically, a role for serotonin metabolism has been supported by the clinical efficacy of serotonin reuptake inhibitors in blocking the development of IFN-alpha-induced depression, and the capacity of IFN-alpha to activate metabolic enzymes (indolamine 2,3 dioxygenase) and cytokine signaling pathways (p38 mitogen activated protein kinase) that can influence the synthesis and reuptake of serotonin. Our data also support a role for dopamine depletion as reflected by IFN-alpha-induced changes in behavior (psychomotor slowing and fatigue) and regional brain activity, which implicate the involvement of the basal ganglia, as well as the association of IFN-alpha-induced depressive-like behavior in rhesus monkeys with decreased cerebrospinal fluid concentrations of the dopamine metabolite, homovanillic acid. Neuroimaging data in IFN-alpha-treated patients also suggest that activation of neural circuits (dorsal anterior cingulate cortex) associated with anxiety and alarm may contribute to cytokine-induced behavioral changes. Taken together, these effects of cytokines on the brain and behavior appear to subserve competing evolutionary survival priorities that promote reduced activity to allow healing, and hypervigilance to protect against future attack. Depending on the relative balance between these behavioral accoutrements of an activated innate immune response, clinical presentations may be distinct and warrant individualized therapeutic approaches.

Clinical experiences and biochemical findings with tacrine (THA)

A clinical comparison of tacrine (THA) and placebo was performed in 15 Alzheimer patients using a double blind crossover technique over 4 plus 4 weeks with one drug-free week in between. Treatment results, as evaluated by clinical rating scales and neuropsychological tests, were mostly negative. Side effects were few, except for elevation liver enzymes which occurred in one third of the patients. CSF levels of the monoamine metabolites HVA and 5-HIAA increased on tacrine as evidence for activation of dopamine and serotonin pathways through cholinergic receptors. Pharmacokinetic investigations showed that the oral bioavailability of tacrine was low and greatly varying between subjects. Patients with high bioavailability of the drug tended to improve more, and also to have more liver enzyme elevations, than those with low bioavailability. A gel preparation for rectal administration was manufactured for comparison of plasma levels attained during one week's treatment with levels attained with oral capsules. Preliminary results indicate that the dose of tacrine can be reduced to 50 per cent when administered rectally, probably as by this route the rapid first-pass metabolism of the drug in the liver is diminished. A clinical trial of tacrine via the rectal route would be justified as this could decrease the number of patients with liver side effects and increase the number of patients improving on the treatment.

Biochemical diagnosis of dopaminergic disturbances in paediatric patients: analysis of cerebrospinal fluid homovanillic acid and other biogenic amines

Homovanillic acid (HVA) is a major catabolite of dopamine. Its concentration in cerebrospinal fluid (CSF) provides insight into the turnover of dopamine. Our main purpose in this review was to analyze the role played by HVA determination in CSF as a diagnostic and prognostic tool in diseases that directly or indirectly affect the dopaminergic pathway in paediatric patients. There are several rare genetic diseases related with dopamine metabolism disturbances, both in the biosynthesis and catabolism of this neurotransmitter, so that diagnosis is often a major challenge. Decreased concentrations of CSF HVA, together with defects in other biogenic amine metabolites, are the hallmark of dopamine deficiency, and they may provide not only a clue for diagnosis but also information about prognosis and treatment monitoring. Concerning secondary deficiencies, genetic and non-genetic conditions have been identified as the cause of low CSF HVA concentrations, and the variability of clinical presentation and pathophysiological mechanisms is wide. As to CSF HVA analysis, lumbar puncture following a strict protocol has been applied for diagnosis of paediatric neurotransmitter diseases. Among laboratory methods developed for the analysis of CSF HVA and other biogenic amines, high pressure liquid chromatography with electrochemical detection is the most reliable procedure for clinical laboratories. Reference values should be established in each laboratory since there is a strong association between age and biogenic amine concentrations in CSF.

Two Greek siblings with sepiapterin reductase deficiency

BACKGROUND

Sepiapterin reductase (SR) deficiency is a rare inherited disorder of neurotransmitter metabolism; less than 25 cases have been described in the literature so far.

METHODS

We describe the clinical history and extensive cerebrospinal fluid (CSF) and urine examination of two Greek siblings with the diagnosis of SR deficiency. The diagnosis was confirmed by enzyme activity measurement in cultured fibroblasts and by mutation analysis.

RESULTS

Both patients suffered from a progressive and complex L-dopa responsive movement disorder. Very low concentrations of the neurotransmitter metabolites homovanillic acid (HVA), 5-hydroxyindolacetic acid (5-HIAA) and 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) were observed in CSF. CSF neopterin and biopterin concentrations were abnormal in one case only, whereas in both cases sepiapterin concentrations were abnormally high and 5-hydroxytryptophan was undetectable. Urine concentrations of HVA, 5-HIAA and vanillyl mandelic acid (VMA) were decreased in both cases. Both patients had no detectable SR enzyme activity in primary dermal fibroblasts, and upon analysis of genomic DNA revealed the same homozygous point mutation introducing a premature stop codon into the reading frame of the SPR gene (mutant allele K251X).

CONCLUSIONS

Our cases illustrate that, apart from HVA and 5-HIAA analysis, the specific quantification of sepiapterin in CSF, rather than neopterin and biopterin alone, is crucial to the final diagnosis of SR deficiency. In addition, urinary concentrations of neurotransmitter metabolites may be abnormal in SR deficiency and may provide an initial indication of SR deficiency before CSF analysis is performed. The known, impressive beneficial response of SR deficient patients to treatment with L-dopa, is illustrated again in our cases.

Outcome and long-term follow-up of 36 patients with tetrahydrobiopterin deficiency

We describe the treatment, the clinical, and biochemical findings and the outcome of 26 patients with 6-pyruvoyl-tetrahydropterin synthase (PTPS) deficiency and 10 patients with dihydropteridine reductase (DHPR) deficiency. These are the two most common forms of the autosomal-recessively inherited tetrahydrobiopterin (BH4) deficiency. Time of diagnosis, dosage of BH4 and neurotransmitter precursors, folinic acid substitution, and levels of 5-hydroxyindoleacetic acid (5HIAA) and homovanillic acid (HVA) in cerebrospinal fluid (CSF) are essential parameters in the follow-up of patients. Unfortunately, treatment protocols vary greatly among patients and clinical centers, and CSF investigations and outcome assessments are not always available. Seventeen patients with PTPS deficiency and four patients with DHPR deficiency were diagnosed within 2 months after birth. In 14 patients with PTPS deficiency (54%; 9 early and 5 late diagnosed) and 2 patients with DHPR deficiency (20%; all early diagnosed) no developmental delay is observed, while in 10 patients with PTPS deficiency (38%; 6 early and 4 late diagnosed) and 8 patients with DHPR deficiency (80%; 2 early and 6 late diagnosed) development was delayed. Two PTPS-deficient patients died in the newborn period. DHPR deficiency seems to be more severe than PTPS deficiency and it is clearly the onset of treatment that determines the outcome. Our data suggest that diagnosis within the first month of life is essential for a good outcome and that low CSF5 HIAA and HVA values in CSF could be an indicator for the ongoing developmental impairment

No association between a TPH2 promoter polymorphism and mood disorders or monoamine turnover

BACKGROUND

Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in serotonin synthesis. TPH2 is a recently discovered isoform that is expressed predominantly in serotonin neurons. Associations are reported of TPH2 polymorphisms with MDD, bipolar disorder and suicidal behavior. This study examines a single nucleotide polymorphism in the putative promoter region of the TPH2 gene.

METHODS

One hundred nine bipolar, 324 major depressive disorder, and 130 healthy volunteers were genotyped for the rs4131347 (-C8347G) promoter SNP. Association was assessed with diagnosis, suicide attempt status, severity of psychopathology and cerebrospinal fluid monoamine metabolite levels of 5-HIAA, HVA, and MHPG. General linear models and logistic regression tested the effect of genotype*childhood abuse interactions on psychopathology severity and suicide attempt.

RESULTS

There was no association between genotype and either mood disorder, suicide attempt status, psychopathology severity or CSF monoamine metabolite levels.

CONCLUSIONS

No association was detected between the rs4131347 (-C8347G) SNP in the promoter region of the TPH2 gene and mood disorders, suicidal behavior or monoamine function.

Effects of interferon-alpha on rhesus monkeys: a nonhuman primate model of cytokine-induced depression

BACKGROUND

Interferon (IFN)-alpha is an innate immune cytokine that causes high rates of depression in humans and therefore has been used to study the impact of cytokines on the brain and behavior. To establish a nonhuman primate model of cytokine-induced depression, we examined the effects of IFN-alpha on rhesus monkeys.

METHODS

Eight rhesus monkeys were administered recombinant human (rHu)-IFN-alpha (20 MIU/m(2)) or saline for 4 weeks in counterbalanced fashion, and videotaped behavior, as well as plasma and cerebrospinal fluid (CSF), were obtained at regular intervals to assess behavioral, neuroendocrine, immune, and neurotransmitter parameters. Additionally, expression and activity of IFN-alpha/beta receptors in monkey peripheral blood mononuclear cells (PBMCs) were assessed.

RESULTS

Compared with saline treatment, IFN-alpha administration was associated with persistent increases in anxiety-like behaviors and decreases in environmental exploration. In addition, IFN-alpha induced significant increases in plasma concentrations of corticotropin (ACTH), cortisol, and interleukin-6 that tended to diminish after chronic administration, especially in dominant animals. Interestingly, in three animals, depressive-like, huddling behavior was observed. Monkeys that displayed huddling behavior exhibited significantly higher plasma concentrations of ACTH and lower CSF concentrations of the dopamine metabolite homovanillic acid. Rhesus monkey PBMCs were found to express mRNA and protein for the IFN-alpha/beta receptor. Moreover, treatment of PBMCs with rHu-IFN-alpha led to induction of STAT1, one of the primary IFN-alpha-induced signaling molecules.

CONCLUSIONS

IFN-alpha evoked behavioral, neuroendocrine, and immune responses in rhesus monkeys that are similar to humans. Moreover, alterations in hypothalamic-pituitary-adrenal axis responses and dopamine metabolism may contribute to IFN-alpha-induced depressive-like huddling behavior.

Secondary abnormalities of neurotransmitters in infants with neurological disorders

Neurotransmitters are essential in young children for differentiation and neuronal growth of the developing nervous system. We aimed to identify possible factors related to secondary neurotransmitter abnormalities in pediatric patients with neurological disorders. We analyzed cerebrospinal fluid (CSF) and biogenic amine metabolites in 56 infants (33 males, 23 females; mean age 5.8mo [SD 4.1mo] range 1d-1y) with neurological disorders whose aetiology was initially unknown. Patients were classified into three clinical phenotypes: epileptic encephalopathy, severe motor impairment, and non-specific manifestations. All patients showed normal results for screening of inborn errors of metabolism. We report clinical, neuroimaging, and follow-up data. Among the patients studied, 10 had low homovanillic acid (HVA) levels and in four patients, 5-hydroxyindoleacetic acid (5-HIAA) was also reduced. Patients with neonatal onset had significantly lower levels of HVA than a comparison group. HVA deficiency was also associated with severe motor impairment and the final diagnosis related to neurodegenerative disorders. 5-HIAA values tended to be decreased in patients with brain cortical atrophy. The possibility of treating patients with L-Dopa and 5-hydroxytryptophan, in order to improve their neurological function and maturation, may be considered.

Monoamine metabolites level in CSF is related to the 5-HTT gene polymorphism in treatment-resistant depression

The serotonin (5-hydroxytryptamine) transporter (5-HTT) is considered to affect the pathogenesis of mood disorders. Large number of genetic association studies between 5-HTT functional polymorphisms and vulnerability of mood disorders and therapeutic response to antidepressants has been carried out. We investigated the influence of 5-HTT-linked polymorphic region (5-HTTLPR) and 5-HTT 17 bp variable number of tandem repeat polymorphism (5-HTTVNTR) polymorphisms on concentrations of monoamine metabolites in cerebrospinal fluid (CSF) among treatment-resistant patients with mood disorders. Subjects were 119 Swedish patients with persistent mood disorders and 141 healthy subjects. In 112 of these patients, we measured 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), and 3-methoxy-4-hydroxyphenylglycol in CSF. Genotyping for 5-HTT polymorphisms from genomic DNA was carried out by PCR. There was no significant difference in allele/genotype frequency between patients and healthy subjects. In patients with mood disorders, we found significant difference in mean 5-HIAA concentration between 5-HTTLPR genotypes (p=0.03). Although the 5-HIAA concentration showed a tendency to be higher in short (S) carriers than in non-S carriers of the 5-HTTLPR in patients (p=0.06), when considering patients with major depressive disorder (MDD), the 5-HIAA concentration was significantly higher among S carriers than among non-S carriers (p=0.02). Moreover, the 5-HIAA concentration was higher in S/S subjects compared to long (L)/L (p=0.0001) and L/S (p=0.002) subjects in patients with MDD. Similarly, there was higher HVA concentration in S/S subjects compared to L/L (p=0.002) and L/S subjects (p=0.002). There was no effect of 5-HTTVNTR. Our findings show that the 5-HTTLPR polymorphism affects 5-HIAA and HVA concentrations among treatment-resistant patients with mood disorders.

Biochemical effects of antidepressant treatment--studies of monoamine metabolites in cerebrospinal fluid and platelet [3H]imipramine binding

Two putative markers of serotonergic function, the concentrations of the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) and the binding parameters of [3H]imipramine to blood platelets, are discussed. Pretreatment concentrations of 5-HIAA in the cerebrospinal fluid (CSF) are lower in depressed patients than in normal controls, and a low concentration of the metabolite is associated with an increased risk of suicide. Many studies have attempted to use pretreatment concentrations of 5-HIAA, of the noradrenaline metabolite 3-methoxy-4-hydroxyphenylglycol (MHPG) and of the dopamine metabolite homovanillic acid (HVA) as predictors of therapeutic effect. On the whole, HVA appears to predict the effects of diverse treatments rather better than 5-HIAA. Treatment with antidepressant drugs changes the amine metabolite concentrations in the CSF in a relatively predictable way. Thus, administration of selective inhibitors of serotonin uptake has a more profound effect on CSF 5-HIAA, while noradrenaline uptake inhibitors preferentially reduce CSF MHPG concentrations. The Bmax of [3H]imipramine binding to blood platelets has been found to be lower in untreated depressed patients than in healthy controls in several studies. In a study from our group, three weeks' treatment with the serotonin uptake blockers zimeldine and alaproclate increased Bmax, while neither nortriptyline nor electroconvulsive treatment caused any change in Bmax after this time period. One year after initiation of treatment, patients who had clinically recovered and were no longer taking drugs still had a low Bmax of [3H]imipramine platelet binding. Prophylactic lithium caused a significant, but transient decrease in the Bmax of platelet [3H]imipramine binding in euthymic bipolar patients.

Aromatic L-amino acid decarboxylase enzyme activity in deficient patients and heterozygotes

BACKGROUND

Aromatic L-amino acid decarboxylase (AADC) deficiency is a rare autosomal recessive disorder characterised by developmental delay, motor retardation and autonomic dysfunction. Very low concentrations in cerebrospinal fluid (CSF) of homovanillic acid (HVA) and 5-hydroxy indole acetic acid (5-HIAA) are suggestive, but not specific, for this disorder. Confirmation of the diagnosis AADC deficiency is then required by enzyme activity measurement or genetic analysis.

METHODS

We describe assays for plasma AADC enzyme activity using both of its substrates, 5-hydroxytryptophan (5-HTP) and 3,4-dihydroxyphenylalanine (L-dopa). We measured AADC activity in controls, AADC deficient patients and heterozygotes.

RESULTS

AADC enzyme activity in control plasma on average is a factor 8-12 higher with L-dopa as substrate than with 5-HTP. Both substrates of AADC compete for the same active site of the enzyme resulting in equally decreased residual enzyme activities in AADC deficient patients. In AADC deficient patients, the enzyme activity towards both substrates, L-dopa and 5-HTP, are equally decreased, as are the CSF concentrations of HVA, 5-HIAA and MHPG, whereas heterozygotes have intermediate AADC activity levels.

CONCLUSIONS

The presently described assays for AADC activity measurement allow an efficient, reproducible and non-invasive way to confirm the diagnosis of AADC deficiency. Since AADC enzyme activity is much higher with L-dopa as a substrate, this method is to be preferred over activity measurement with 5-HTP as a substrate for diagnostic purposes.

Sex and genetic associations with cerebrospinal fluid dopamine and metabolite production after severe traumatic brain injury

Object

Dopamine (DA) pathways have been implicated in cognitive deficits after traumatic brain injury (TBI). Both sex and the dopamine transporter (DAT) 3′ variable number of tandem repeat polymorphism have been associated with differences in DAT protein density, and DAT protein affects both presynaptic DA release, through reverse transport, and DA reuptake. Catecholamines and associated metabolites are subject to autooxidation, resulting in the formation of reactive oxygen species that may contribute to subsequent oxidative injury. The purpose of this study was to determine associations between factors that affect DAT expression and cerebrospinal fluid (CSF) DA and metabolite levels after severe TBI.

Methods

Sixty-three patients with severe TBI (Glasgow Coma Scale score ≤ 8) were evaluated. The patients' genotypes were obtained using previously banked samples of CSF, and serial CSF samples (416 samples) were used to evaluate DA and metabolite levels. High-performance liquid chromatography was used to determine CSF levels of DA, 3,4-dihydroxyphenylacetic acid (DOPAC), and homovanillic acid (HVA) during the first 5 days after injury.

Mixed-effects multivariate regression modeling revealed that patients with the DAT 10/10 genotype had higher CSF DA levels than patients with either the DAT 9/9 or DAT 9/10 genotypes (p = 0.009). Females with the DAT 10/10 genotype had higher CSF DA levels than females with the DAT 9/9 or DAT 9/10 genotypes, and sex was associated with higher DOPAC levels (p = 0.004). Inotrope administration also contributed to higher DA levels (p = 0.002).

Conclusions

In addition to systemic administration of DA, inherent factors such as sex and DAT genotype affect post-TBI CSF DA and DA metabolite levels, a phenomenon that may modulate susceptibility to DA-mediated oxidative injury.

CSF monoamine metabolites and lethality of suicide attempts in depressed patients with alcohol dependence

BACKGROUND

Alcohol dependence (alcoholism) and major depressive disorder are frequently comorbid and are risk factors for suicidal behavior. Monoaminergic abnormalities have been implicated in the pathophysiology of depression, alcohol dependence, and suicidal behavior. Lower cerebrospinal fluid (CSF) 5-hydroxyindolacetic acid (5-HIAA) levels are associated with higher lethality of suicide attempts in major depression and predict a higher rate of future suicide. We sought to study the relationship of CSF monoamine metabolites to lethality of suicidal acts in depressed subjects with comorbid alcoholism.

METHODS

We compared 16 high- and 16 low-lethality drug-free depressed suicide attempters with comorbid alcoholism. Subjects were free from any substance use disorder for at least two months. Demographic and clinical parameters, and CSF 5-HIAA, homovanillic acid (HVA), and 3-methoxy-4-hydroxyphenylglycol (MHPG) levels were examined.

RESULTS

The two groups did not differ with regard to the demographic characteristics. CSF 5-HIAA levels were lower in high-lethality attempters compared to low-lethality attempters. There were no group difference in CSF HVA or MHPG levels.

CONCLUSION

Higher lethality of suicidal behavior in depressed patients with alcoholism is related to lower serotonergic activity.

Cerebrospinal fluid kynurenic acid in male and female controls - correlation with monoamine metabolites and influences of confounding factors

The concentrations of the tryptophan metabolite kynurenic acid (KYNA) and the monoamine metabolites homovanillic acid (HVA), 5-hydroxy-indoleacetic acid (5-HIAA) and 4-hydroxy-3-methoxyphenylglycol (HMPG) were determined in the cerebrospinal fluid (CSF) from 43 healthy volunteers (30 males and 13 females). Healthy female controls displayed higher CSF concentration of KYNA (1.91nM+/-0.20) compared to healthy male controls (1.06nM+/-0.07) and lower CSF levels of HMPG (39.2nM+/-2.0 and 43.4+/-1.2, respectively). CSF levels of HVA and 5-HIAA did not differ between females (181.3nM+/-21.9 and 93.7nM+/-11.4, respectively) and males (138.9nM+/-12.6 and 74.8nM+/-5.9, respectively). Positive intercorrelations were found between CSF KYNA, HVA and 5-HIAA while CSF content of HMPG did not correlate with KYNA or the other monoamine metabolites in CSF. A negative correlation was found between back length and CSF concentrations of KYNA, HVA and 5-HIAA and also between CSF KYNA levels and body height. The results of the present study suggest that concentrations of KYNA and the monoamine metabolites in CSF from healthy controls are dependent on gender and back length, which must be taken in consideration when analysing mixed groups of men and women. The higher KYNA concentration found in female controls compared to male might be attributed to a shorter back in women compared to men. Furthermore, these findings suggest that increased KYNA formation is associated with an increased dopamine and serotonin turnover.

Serotonergic influences on life-history outcomes in free-ranging male rhesus macaques

Several studies have demonstrated that nonhuman primate males with low cerebrospinal fluid (CSF) levels of the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) exhibit antisocial behavior patterns. Included in these deleterious patterns are impulse control deficits associated with violence and premature death. No studies to date have longitudinally studied the long-term outcome of young subjects with low CSF 5-HIAA concentrations as they mature into adults. In this study we examined longitudinal relations among serotonergic and dopaminergic functioning, as reflected in CSF metabolite concentrations, aggression, age at emigration, dominance rank, and mortality in free-ranging rhesus macaque (Macaca mulatta) males. Our results indicate long-term consistency of individual differences in levels of 5-HIAA in CSF in the subject population from the juvenile period of development through adulthood. We found a significant negative correlation between 5-HIAA concentrations measured in juveniles and rates of high-intensity aggression in the same animals as adults. Further, CSF 5-HIAA concentrations were lower in juveniles that died than in animals that survived. For the young animals that migrated there was a positive correlation between CSF 5-HIAA concentration and age at emigration, whereas for the animals that remained in their troop until later in sexual maturity there was a negative correlation between CSF 5-HIAA concentration and age of emigration. After animals emigrated to a new troop, social dominance rank in the new troop was positively correlated with early family social dominance rank, but inversely correlated with juvenile CSF 5-HIAA concentrations. Taken together, our findings suggest that males with low central serotonin levels early in life delay migration and show high levels of violence and premature death, but the males that survive achieve high rank. These findings indicate that longitudinal measures of serotonergic and dopaminergic functioning are predictive of major life-history outcomes in nonhuman primate males. Low concentrations of CSF 5-HIAA are associated with negative life-history patterns characterized by social instability and excessive aggression, and positive life-history patterns characterized by higher dominance rank.

A review of prospective studies of biologic predictors of suicidal behavior in mood disorders

Predicting suicide is difficult due to the low base rate, even in high-risk groups, and the multi-causal nature of suicidal behavior. Clinical predictors have shown low specificity. Retrospective and cross-sectional studies have identified a number of biologic anomalies associated with suicide and suicide attempt. Prospective studies provide estimates of the predictive utility of biologic measures. Here we review prospective studies of suicidal behavior and serotonergic, noradrenergic, dopaminergic and hypothalamic-pituitary-adrenocortical axis function in mood disorders. The most promising biologic predictors are low CSF 5-HIAA and HPA axis dysfunction as demonstrated by dexamethasone non-suppression that are each associated with about 4.5 fold greater risk of suicide.

A study of CSF catecholamine and its metabolites in acute and convalescent period of encephalitis

AIMS

To evaluate cerebrospinal fluid (CSF) catecholamine (CA) and its metabolites in encephalitis patients in acute and convalescent period and correlate these with clinical and magnetic resonance imaging (MRI) features.

SUBJECTS AND METHODS

Patients with acute encephalitis diagnosed on the basis of clinical, CSF, MRI and virological parameters underwent detailed neurological evaluation including Glasgow Coma Scale (GCS), Unified Parkinson's Disease Rating Scale (UPDRS) and Dystonia Rating Scale. Cranial MRI was carried out and CSF dopamine (DA), norepinephrine (NE), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxytryptamine (5HT) levels were estimated by High Performance Liquid Chromatography (HPLC). The CSF catecholamine levels were compared with convalescent phase as well as with controls. These levels were also correlated with parkinsonian features, dystonia and radiological abnormalities.

RESULTS

There were 29 encephalitis patients; whose age ranged between 2 and 65 years, 4 were females and 11 children. 25 patients had Japanese encephalitis (JE) and 4 nonspecific encephalitis. The mean GCS score was 8 and 13 had seizures. Movement disorders were present in 13 patients and included parkinsonian features in 5, dystonia in 1 and combination of both in 7 patients. MRI revealed abnormalities in 15 out of 21 patients and included thalamic lesion in 10, globus pallidus in 4, putamen in 5, caudate in 4 and midbrain in 9 patients. In acute stage NE, DOPAC, 5HT and HVA levels were significantly lower compared to controls. NE levels significantly correlated with dystonia and thalamic lesions. Convalescent CSF study revealed significantly lower levels of DOPAC compared to acute phase. CSF catecholamine levels in encephalitis patients with and without movement disorders were not significantly different.

CONCLUSION

In encephalitis, catecholamine and its metabolites are lower in acute and convalescent phase. Norepinephrine level correlates with dystonia and thalamic lesions.

The relationship between CSF HVA/5-HIAA ratio and suicide intent in suicide attempters

There is a need to find stable biomarkers for suicidal behavior and suicide prediction. Reduced homovanillic acid/5-hydroxyindolacetic acid (HVA/5-HIAA) ratios in cerebrospinal fluid (CSF) in depressed suicide attempters have been reported. Suicide intent is a predictor of repetition of attempts and suicide. In the present study we investigated the relationship of HVA/5-HIAA ratio to the scales rating suicide intent and depressive symptoms. Fifteen consecutive medication-free male suicide attempters admitted to a psychiatric ward at the Karolinska Hospital and eight healthy male volunteers underwent lumbar puncture and had the CSF monoamine metabolite levels assayed. Patients were assessed with the Beck Suicide Intent Scale (SIS), the Montgomery Asberg Depression rating Scale (MADRS) and the Chapman Scale of Anhedonia. Within the suicide attempter group, HVA/5-HIAA ratio was significantly associated with the Suicide Intent Scale (SIS), but not with the MADRS scale or the Chapman Scale of Anhedonia indicating that the HVA/5-HIAA ratio may be a biomarker of suicide intent.

Early maternal rejection affects the development of monoaminergic systems and adult abusive parenting in rhesus macaques (Macaca mulatta)

This study investigated the effects of early exposure to variable parenting style and infant abuse on cerebrospinal fluid (CSF) concentrations of monoamine metabolites and examined the role of monoaminergic function in the intergenerational transmission of infant abuse in rhesus monkeys (Macaca mulatta). Forty-three infants reared by their biological mothers and 15 infants that were cross-fostered at birth and reared by unrelated mothers were followed longitudinally through their first 3 years of life or longer. Approximately half of the infants were reared by abusive mothers and half by nonabusive controls. Abused infants did not differ from controls in CSF concentrations of 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), or 3-methoxy-4-hydroxyphenylgycol (MHPG). Abused infants, however, were exposed to higher rates of maternal rejection, and highly rejected infants had lower CSF 5-HIAA and HVA than low-rejection infants. The abused females who became abusive mothers in adulthood had lower CSF 5-HIAA than the abused females who did not. A similar trend was also observed among the cross-fostered females, suggesting that low serotonergic function resulting from early exposure to high rates of maternal rejection plays a role in the intergenerational transmission of infant abuse.

Cerebrospinal fluid monoamine metabolite levels in human newborn infants born in winter differ from those born in summer

An earlier study has shown significant differences in the CSF monoamine metabolite levels in adults born during different seasons of the year. We study here the relationship between season of birth and CSF monoamine metabolite levels in 283 newborn febrile infants without neurological abnormalities, with an age distribution ranging from birth to about 3 months, adjusting for the confounding variables age and time at lumbar puncture, weight at birth, estimated gestational age at birth, gender, race, and medicaid status. Each of the three metabolite levels as well as their ratios HVA/5-HIAA and 5-HIAA/MHPG showed significant month-of-birth variations, but not the ratio HVA/MHPG. For HVA and MHPG levels, the maximum was obtained around the winter birth months November-December, whereas for 5-HIAA level, the maximum was obtained around the summer birth months June-July. The correlations between HVA and 5-HIAA were, in general, significantly positive within the different birth seasons and races. Among summer-born Caucasian infants, MHPG was significantly positively correlated with HVA and with 5-HIAA, whereas among winter-born Black infants, MHPG was significantly positively correlated with HVA. Season of birth is an unspecific environmental factor that may be proxy for several possible seasonally varying environmental circumstances such as the length of photoperiod, temperature, infections, nutrition, stress and lifestyle. Studies relating season of birth to monoaminergic turnover at different stages of life may yield important clues about the gestational and perinatal origins of neurodevelopment.

A prospective study of the association of cerebrospinal fluid monoamine metabolite levels with lethality of suicide attempts in patients with bipolar disorder

OBJECTIVES

Bipolar disorder is a severe illness that is associated with suicidal behavior. A biological predictor of highly lethal suicide attempts in patients with bipolar disorder would be valuable. We hypothesized that cerebrospinal fluid (CSF) monoamine metabolite levels are related to lethality of suicide attempts in bipolar patients and examined the relation between CSF 5-hydroxyindolacetic acid (5-HIAA), homovanillic acid (HVA), and 3-methoxy-4-hydroxyphenylglycol (MHPG) levels and maximum lethality of suicide attempts at baseline and during a 2-year follow up.

METHODS

Twenty-seven bipolar depressed patients participated in the study. Demographic and clinical parameters were examined and recorded. Lumbar punctures were performed and CSF 5-HIAA, HVA, and MHPG were assayed by high-performance liquid chromatography with electrochemical detection. Following discharge, patients were evaluated after 3 months, 1 year, and 2 years. Each follow-up interview included an in-depth assessment of suicidal behavior during the intervening time period.

RESULTS

Six subjects made suicide attempts during the 2-year follow-up. Bipolar patients who attempted suicide during the follow-up period had higher aggression and hostility scale scores compared to bipolar subjects who did not make a suicide attempt during the follow-up period. CSF 5-HIAA, HVA, and MHPG levels were negatively correlated with the maximum lethality of suicide attempts during the 2-year follow-up period.

CONCLUSIONS

Our finding is the first observation that CSF monoamine metabolite levels may be predictors of lethality of suicide attempts in patients with bipolar disorder. Further studies are necessary to answer the question whether CSF monoamine metabolite levels are clinically useful biochemical predictors of highly lethal suicide attempts or completed suicides.

Influence of parenting style on the offspring's behaviour and CSF monoamine metabolite levels in crossfostered and noncrossfostered female rhesus macaques

We investigated the association between variation in parenting style and the offspring's behaviour and CSF monoamine metabolite (5-HIAA, HVA, and MHPG) levels in rhesus monkeys. Study subjects were 25 two-year-old females reared by their biological mothers and 15 same-aged females that were crossfostered at birth and reared by unrelated mothers. Subjects that were rejected more by their mothers in the first 6 months of life engaged in more solitary play and had lower CSF concentrations of 5-HIAA than subjects that were rejected less. The relation between these variables was generally similar in crossfostered and noncrossfostered females. CSF levels of 5-HIAA were negatively correlated with rates of scratching, a behavioural indicator of anxiety. These results suggest that that early exposure to high rates of maternal rejection can result in higher anxiety later in life, and that this effect may be mediated by serotonergic mechanisms. Variation in maternal protectiveness did not affect offspring behaviour and neither protectiveness nor rejection affected CSF levels of HVA and MHPG. CSF levels of MHPG, however, were negatively correlated with solitary play behaviour and avoidance of other individuals, suggesting that individuals with lower CSF MHPG were more fearful and socially phobic than those with higher CSF MHPG. Taken together, these findings suggest that individual differences in anxiety and fearfulness in young rhesus monkeys are accounted for, at least in part, by variation in CSF levels of monoamine metabolites, and that the development of brain monoamine systems, particularly serotonin, can be affected by early exposure to variable maternal behaviour.

CSF analysis differentiates multiple-system atrophy from idiopathic late-onset cerebellar ataxia

BACKGROUND

Differentiating idiopathic late-onset cerebellar ataxia (ILOCA) from ataxia due to the cerebellar subtype of multiple-system atrophy (MSA-C) can be difficult in the early stages of the disease

METHODS

The authors analyzed the levels of various CSF biomarkers in 27 patients with MSA-C and 18 patients with ILOCA and obtained cut-off points for each potential biomarker to differentiate MSA-C from ILOCA.

RESULTS

Increased levels of neurofilament light chain (NFL) and neurofilament heavy chain (NFHp35) and decreased levels of the neurotransmitter metabolites homovanillic acid (HVA), 5-hydroxyindoleaceticacid (5-HIAA), and 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) were observed in MSA-C compared with ILOCA patients. Receiver operating characteristic analysis showed high sensitivity and specificity levels for NFL, NFHp35, and MHPG analysis. At a cut-off of 24.4 ng/L for the NFL analysis, a sensitivity of 79% and a specificity of 94% were obtained for differentiating MSA-C from ILOCA. At a cut-off point for NFHp35 of 129.5 ng/L, sensitivity was 87% and specificity 83%. Analysis of MHPG levels (cut-off 42.5 nM) resulted in a sensitivity of 86% with a specificity of 75%. A multivariate logistic regression model selected NFL, MHPG, and tau as independent predictive biomarkers that separated the MSA-C and ILOCA groups.

CONCLUSIONS

Increased levels of neurofilament light chain and tau and decreased levels of 3-methoxy-4-hydroxyphenylethyleneglycol were associated with high accuracy levels in differentiating the cerebellar subtype of multiple-system atrophy from idiopathic late-onset cerebellar ataxia (LOCA). CSF analysis may thus serve as a useful tool in early diagnostic differentiation of LOCA.

A functional polymorphism in the MAOA gene promoter (MAOA-LPR) predicts central dopamine function and body mass index

Variation in brain monoaminergic activity is heritable and modulates risk of alcoholism and other addictions, as well as food intake and energy expenditure. Monoamine oxidase A deaminates the monoamine neurotransmitters serotonin, dopamine (DA), and noradrenaline. The monoamine oxidase A (MAOA) gene (Xp11.5) contains a length polymorphism in its promoter region (MAOA-LPR) that putatively affects transcriptional efficiency. Our goals were to test (1) whether MAOA-LPR contributes to interindividual variation in monoamine activity, assessed using levels of cerebrospinal fluid (CSF) monoamine metabolites; and (2) whether MAOA-LPR genotype influences alcoholism and/or body mass index (BMI). Male, unrelated criminal alcoholics (N=278) and controls (N=227) were collected from a homogeneous Finnish source population. CSF concentration of 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), and 3-methoxy-4-hydroxyphenylglycol (MHPG) were available from 208 participants. Single allele, hemizygous genotypes were grouped according to inferred effect of the MAOA alleles on transcriptional activity. MAOA-LPR genotypes had a significant effect on CSF HVA concentration (P=0.01) but explained only 3% of the total variance. There was a detectable but nonsignificant genotype effect on 5-HIAA and no effects on MHPG. Specifically, the genotype conferring high MAOA activity was associated with lower HVA levels in both alcoholics and controls, a finding that persisted after accounting for the potential confounds of alcoholism, BMI, height, and smoking. MAOA-LPR genotype predicted BMI (P<0.005), with the high-activity genotype being associated with lower BMI. MAOA-LPR genotypes were not associated with alcoholism or related psychiatric phenotypes in this data set. Our results suggest that MAOA-LPR allelic variation modulates DA turnover in the CNS, but does so in a manner contrary to our prior expectation that alleles conferring high activity would predict higher HVA levels in CSF. Our results are consistent with an emerging literature that suggests greater complexity in how variation in MAOA expression alters monoaminergic function. Finally, our work suggests that MAOA may be involved in the regulation of BMI. Independent samples are necessary to confirm this preliminary finding.

Elevated putamen D(2) receptor binding potential in major depression with motor retardation: an [11C]raclopride positron emission tomography study

OBJECTIVE

Several antidepressants raise striatal dopamine, but the role of striatal dopamine during major depressive episodes is unclear. Striatal [(11)C]raclopride binding potential measured with positron emission tomography is an index of D(2) type receptors and is sensitive to extracellular dopamine levels (higher D(2) binding potential occurs when dopamine is lower). It was hypothesized that putamen D(2) binding potential would be higher during major depressive episodes featuring motor retardation.

METHOD

Drug-free, nonsmoking subjects experiencing a major depressive episode (N=21) underwent [(11)C]raclopride PET imaging as did 21 healthy age-matched comparison subjects. Motor retardation was measured with the finger tapping test.

RESULTS

The depressed subjects exhibiting motor retardation had significantly higher D(2) binding potential in both the left and right putamen than did healthy subjects, and putamen D(2) binding potential correlated significantly with motor speed in the depressed subjects.

CONCLUSIONS

The results argue that extracellular dopamine is lower in subjects experiencing a major depressive episode that features motor retardation. This depression subtype should preferentially benefit from dopamine-increasing medications and should be targeted in future clinical trials of dopamine reuptake inhibitors.

Circadian changes in CSF dopaminergic measures in restless legs syndrome

BACKGROUND AND PURPOSE

Restless legs syndrome (RLS) has a circadian component with symptoms being prominent at night. The dopaminergic (DAergic) system, which plays a role in RLS, entails circadian changes that parallel RLS symptom changes. The aim of this study was to look for relative and diurnal differences in DAergic activity.

PATIENTS AND METHODS

All RLS subjects were treated prior to their enrollment in the study but were all drug-free for at least 2 weeks prior to evaluation. Cerebrospinal fluid (CSF) collected at 10 p.m. was used to determine DA-related co-factors and metabolites. These were compared to CSF values collected in a previous study at 10 a.m.

RESULTS

The only significant finding from the 10 p.m. samples (30 RLS; 22 control) was increased 3-ortho-methyldopa (3OMD) for RLS compared to controls. A comparison of the 10 p.m. to 10 a.m. values (16 RLS; 9 controls) showed small, non-significant diurnal changes for controls but large diurnal changes in tetrahydrobiopterin (BH4), HVA:5HIAA ratio and 3OMD for RLS, with the 10 a.m. sample showing increases in all three CSF factors compared to the 10 p.m. sample.

CONCLUSIONS

The greater diurnal changes in RLS suggest greater fluctuations than normal in DAergic circadian dynamics. The increased 3OMD concentration in the absence of concurrent exogenous levodopa (l-dopa) suggests changes in synthesis or metabolism of l-dopa in RLS.