Depression in Parkinson's disease. Pharmacological characteristics and treatment

Behind the Mask: Parkinson's Disease and Depression

Parkinson's disease (PD) is a common, prevalent neurodegenerative disease. It is mainly characterized by motor symptoms such as rigidity, tremors, and bradykinesia, but it can also manifest with non-motor symptoms, of which depression is the most frequent. The latter can impair the quality of life, yet it gets overlooked and goes untreated because of the significant overlap in their clinical features, hence making the diagnosis difficult. Furthermore, there is limited data on the availability of appropriate criteria for making the diagnosis of depression in PD patients, as it can occur with varying expressions throughout the course of PD or it can also precede it. This review article has included a brief discussion on the diagnosis of depression in PD patients and their overlapped clinical manifestations. Understanding the mechanisms underlying the disease processes of PD and depression and the pathways interconnecting them gives better knowledge on devising treatment options for the patients. Only studies from Pubmed were included and all other databases were excluded. Studies from the last 50 years were included. Suitable references included in these studies were also extracted. Thus, depression in PD and PD in depression, along with their pharmacological and non-pharmacological treatment options, have been discussed.

Exploring depression in Parkinson's disease: an Italian Delphi Consensus on phenomenology, diagnosis, and management

BACKGROUND

Depression is a prodromic and a frequent non-motor symptom of Parkinson's disease, associated to reduced quality of life and poor outcomes. The diagnosis of depression in parkinsonian patients represents a challenge due to the overlapping of symptoms typical of the two conditions.

METHODS

A Delphi panel survey was performed to reach a consensus amongst different Italian specialists on four main topics: the neuropathological correlates of depression, main clinical aspects, diagnosis, and management of depression in Parkinson's disease.

RESULTS AND CONCLUSION

Experts have recognized that depression is an established risk factor of PD and that its anatomic substrate is related to the neuropathological abnormalities typical of the disease. Multimodal and SSRI antidepressant have been confirmed as a valid therapeutic option in the treatment of depression in PD. Tolerability, safety profile, and potential efficacy on broad spectrum of symptoms of depression including cognitive symptoms and anhedonia should be considered when selecting an antidepressant and the choice should be tailored on the patients' characteristics.

Longitudinal risk factors for developing depressive symptoms in Parkinson's disease

BACKGROUND

Despite the established importance of identifying depression in Parkinson's disease, our understanding of the factors which place the Parkinson's disease patient at future risk of depression is limited.

METHODS

Our sample consisted of 874 patients from two longitudinal cohorts, PPMI and PDBP, with median follow-up durations of 7 and 3 years respectively. Risk factors for depressive symptoms at baseline were determined using logistic regression. A Cox regression model was then used to identify baseline factors that predisposed the non-depressed patient to develop depressive symptoms that were sustained for at least one year, while adjusting for antidepressant use and cognitive impairment. Common predictors between the two cohorts were identified with a random-effects meta-analysis.

RESULTS

We found in our analyses that the majority of baseline non-depressed patients would develop sustained depressive symptoms at least once during the course of the study. Probable REM sleep behavior disorder (pRBD), age, duration of diagnosis, impairment in daily activities, mild constipation, and antidepressant use were among the baseline risk factors for depression in either cohort. Our Cox regression model indicated that pRBD, impairment in daily activities, hyposmia, and mild constipation could serve as longitudinal predictors of sustained depressive symptoms.

CONCLUSIONS

We identified several potential risk factors to aid physicians in the early detection of depression in Parkinson's disease patients. Our findings also underline the importance of adjusting for multiple covariates when analyzing risk factors for depression.

Development of Mixed Anxiety/Depression-Like State as a Consequence of Chronic Anxiety: Review of Experimental Data

The review presents experimental data considered from the point of view of dynamic changes in the brain neurochemistry, physiology, and behavior of animals during the development of mixed anxiety/depression-like disorder caused by chronic social stress from norm to severe psychopathology. Evidences are presented to support the hypothesis that chronic anxiety rather than social defeat stress is an etiological factor in depression. The consequences of chronic anxiety for human health and social life are discussed.

MDGA1-deficiency attenuates prepulse inhibition with alterations of dopamine and serotonin metabolism: An ex vivo HPLC-ECD analysis

MDGA1 (MAM domain-containing glycosylphosphatidylinositol anchor) has recently been linked to schizophrenia and bipolar disorder. Dysregulation of dopamine (DA) and serotonin (5-HT) systems has long been associated with schizophrenia and other neuropsychiatric disorders. Here, we measured prepulse inhibition (PPI) of the startle response and ex vivo tissue content of monoamines and their metabolites in the frontal cortex, striatum and hippocampus of Mdga1 homozygous (Mdga1-KO), Mdga1 heterozygous (Mdga1-HT) and wild-type (WT) male mice. We found that Mdga1-KO mice exhibited statistically significant impairment of PPI, and had higher levels of homovanillic acid in all three brain regions studied compared with Mdga1-HT and WT mice (P < 0.05), while levels of norepinephrine, DA and its metabolites 3,4-dihydroxyphenylacetic acid and 3-methoxytyramine remained unchanged. Mdga1-KO mice also had a lower 5-hydroxyindoleacetic acid level in the striatum (P < 0.05) compared with WT mice. 5-HT levels remained unchanged with the exception of a significant increase in the level in the cortex. These data are the first evidence suggesting that MDGA1 deficiency leads to a pronounced deficit in PPI and plays an important role in perturbation of DA and 5-HT metabolism in mouse brain; such changes may contribute to a range of neuropsychiatric disorders.

Evaluation of Selected Natural Compounds as Dual Inhibitors of Catechol-O-Methyltransferase and Monoamine Oxidase

Background:

The most effective symptomatic treatment of Parkinson’s disease remains the metabolic precursor of dopamine, L-dopa. To enhance the efficacy of L-dopa, it is often combined with inhibitors of the enzymes, catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO) B, key metabolic enzymes of L-dopa and dopamine.

Objective:

This study attempted to discover compounds that exhibit dual inhibition of COMT and MAO-B among a library of 40 structurally diverse natural compounds. Such dual acting inhibitors may be effective as adjuncts to L-dopa and offer enhanced value in the management of Parkinson’s disease.

Methods:

Selected natural compounds were evaluated as in vitro inhibitors of rat liver COMT and recombinant human MAO. Reversibility of MAO inhibition was investigated by dialysis.

Results:

Among the natural compounds morin (IC50 = 1.32 µM), chlorogenic acid (IC50 = 6.17 µM), (+)-catechin (IC50 = 0.86 µM), alizarin (IC50 = 0.88 µM), fisetin (IC50 = 5.78 µM) and rutin (IC50 = 25.3 µM) exhibited COMT inhibition. Among these active COMT inhibitors only morin (IC50 = 16.2 µM), alizarin (IC50 = 8.16 µM) and fisetin (IC50 = 7.33 µM) were noteworthy MAO inhibitors, with specificity for MAO-A.

Conclusion:

None of the natural products investigated here are dual COMT/MAO-B inhibitors. However, good potency COMT inhibitors have been identified, which may serve as leads for future development of COMT inhibitors.

High-frequency repetitive transcranial magnetic stimulation to the left dorsolateral prefrontal cortex of patients with Parkinson's disease and treatment-resistant depression: a pilot study

An increasing amount of evidence is showing the therapeutic effects of rTMS on PD-related non-motor functions neuroanatomically linked to the DLPFC. This presents an ongoing need to apply an optimal combination of stimulation parameters to clinically heterogeneous patient populations, including those with neuropsychiatric problems and other comorbidities along with the neurodegenerative process. In this prospective pilot study, six patients with PD and treatment-resistant depression were thoroughly assessed and carefully monitored before, during, and after each stimulation procedure. The results can provide the basis for developing an extended rTMS protocol that is both effective and safe.

Antidepressant Effects of Repetitive Transcranial Magnetic Stimulation Over Prefrontal Cortex of Parkinson's Disease Patients With Depression: A Meta-Analysis

Objective: The purpose of this meta-analysis was to investigate the antidepressant effects of repetitive transcranial magnetic stimulation (rTMS) over the prefrontal cortex (PFC) of patients with Parkinson's disease (PD) and to determine the optimal rTMS parameters, such as the intensity, frequency and the delivered pattern of rTMS stimulation. Methods: EMBASE, PubMed, Web of Science, MEDLINE, and Cochrane data bases were researched for papers published before March 12, 2018. Studies investigating the anti-depression effects of rTMS over PFC in patients with PD were considered. The main outcomes of pre- and post-rTMS treatment as well as score changes were all extracted. The mean effect size was estimated by calculating the standardized mean difference (SMD) with 95% confidence interval (CI) by using fixed or random effect models as appropriate. Results: Nine studies containing 137 PD patients with depression were included. The pooled results showed significant pre-post anti-depressive effects of rTMS over PFC in PD patients with depression (SMD = -0.80, P < 0.00001). The subgroup analyses of stimulation intensity, frequencies, and models also revealed significant effects (Intensities: 90% RMT: SMD = -1.16, P = 0.0006; >100% RMT: SMD = -0.82, P < 0.0001. Frequencies: < 1.0 Hz: SMD = -0.83, P = 0.03; 5.0 Hz: SMD = -1.10, P < 0.0001; ≥10.0 Hz: SMD = -0.55, P = 0.02. Models: Continuous: SMD = -0.79, P < 0.0001; Discontinuous: SMD = -0.84, P = 0.02). But the results of the studies with place-controlled designs were not significant (Overall: SMD = -0.27, P = 0.54. Intensities: 90% RMT: SMD = 0.27, P = 0.68; 100% RMT: SMD = -0.32, P = 0.33. Frequencies: 5.0 Hz: SMD = -0.87, P = 0.10; ≥10.0 Hz: SMD = 0.27, P = 0.66. Models: Continuous: SMD = -0.28, P = 0.68; Discontinuous: SMD = -0.32, P = 0.33). The greater effect sizes of rTMS with 90% RMT, 5.0 Hz in discontinuous days can be observed rather than the other parameters in both kinds of analyses across study design. Conclusions: rTMS may have a significant positive pre-post anti-depressive effect over PFC on patients with depression, especially by using 5.0 Hz frequency with 90% RMT intensity in discontinuous days, which may produce better effects than other parameters. The real effect, though, was not different from that of the placebo. Future studies with larger sample sizes and high-quality studies are needed to further corroborate our results and to identify the optimal rTMS protocols.

Psychiatric side-effects of medications: recent developments

Medications often induce neuropsychiatric side-effects. This article reviews psychiatric side-effects that are well known and describes those induced by recently developed medications. Therapeutic innovations have been prominent in the treatment of HIV infection, Parkinson's disease and epilepsy and therefore psychiatric side-effects caused by these agents are described in more detail.

Influence of depression in mild Parkinson's disease on longitudinal motor and cognitive function

BACKGROUND

Studies have suggested a relationship between non-motor symptoms with motor fluctuations in patients with Parkinson's disease (PD). We studied the influence of depression on longitudinal motor and cognitive function among mild PD patients.

METHODS

A 1.5 years longitudinal study of 102 patients with mild idiopathic PD. Patients were assessed with a standardized clinical assessment battery including motor and non-motor scales. Patients also underwent serial neurocognitive testing that assessed global cognition, memory, attention, language, visuospatial and executive function.

RESULTS

81 patients with mean age of 64.9(SD = 7.9) years and mean Hoehn & Yahr of 1.9(SD = 0.4) completed baseline and follow-up visits. 22 patients had clinically significant depression at baseline with mean Geriatric Depression Scale of 6.9(SD = 2.4). These patients presented with concomitant apathy and anxiety and were more likely to be females with longer duration of PD. At baseline, patients with depression had poorer performance on global cognition and all cognitive domains although not significantly different from patients without depression. At follow-up, there was no statistically significant difference on cognitive performance between those with and without baseline depression. Patients with baseline depression demonstrated worsening of motor function after 18 months (UPDRS Motor Score Change: +5.0[7.0]vs.+0.2[7.3]; p = 0.015). On multivariate analysis Baseline Motor Score (B = -0.229,CI = -0.445 to-0.013,p = 0.038), Baseline GDS (B = 0.622,CI = 0.078 to 1.166,p = 0.026) and PD duration (B = 0.520,CI = 0.105 to 0.935,p = 0.015) independently predicted increase in UPDRS Motor Score.

CONCLUSIONS

The findings suggest a relationship between early depression with motor worsening and cognition decline in PD patients. Further biomarker-supported studies investigating the role of depression on motor and cognitive function are needed.

Depression in Parkinson's disease: the effectiveness and risk of pharmacotherapy. Clinical review

Parkinson's disease (PD) is a neurological disease with a heterogeneous pattern of neurological symptoms and concomitant psychiatric syndromes. These syndromes are triggered by alterations to neurotransmission that are likely common for both neurological and psychiatric symptoms. Syndromes such as depression, anxiety, or cognitive impairment can precede motor symptoms of PD and delay its diagnosis. Recently, questions related to aetiological factors and treatment strategies of depression in PD have become a growing concern of PD researchers. This article describes the main features of depression in PD and presents current hypotheses on its aetiology and recommended treatment modes.

Depression in Parkinson's Disease

Objective:

To examine predictive factors associated with onset of depression among individuals diagnosed with Parkinson's disease (PD).

Background:

Depression may precede or follow symptomatic parkinsonism in PD. It is frequently treatable but often overlooked.

Methods:

The clinical series comprised 685 individuals who were diagnosed with PD and followed by one neurologist (RJU) from 1994 to 2007. The primary outcome was time to depression following the onset of PD. Diagnosis of depression was based on clinical assessment of depressive symptoms from patients (and spouse/family/caregiver) and antidepressant usage. A number of demographic, historical and clinical predictive factors were examined, including gender, age at symptomatic onset, disease duration, onset characteristics, clinical ratings, antiparkinsonian medications, cognitive status, depression history, and familial history of PD and other neurodegenerative disorders.

Results:

Seventy-two percent of patients developed depression within ten years of symptomatic PD onset, and the mean time to depression was 7.9 years (median: 5.7 years). Factors associated with depression included longer PD duration, greater impairment in activities of daily living, and positive family history of motor neuron disease (MND).

Conclusions:

A high rate of individuals with PD develop depressive symptoms during the course of the disease. Based on first clinic visit characteristics, most factors examined were not helpful in identifying individuals with an increased risk of depression. However, disease duration, functional limitations and family history of MND should lead clinicians to an increased vigilance for identifying depression.

Assessment of cellular estrogenic activity based on estrogen receptor-mediated reduction of soluble-form catechol-O-methyltransferase (COMT) expression in an ELISA-based system

Xenoestrogens are either natural or synthetic compounds that mimic the effects of endogenous estrogen. These compounds, such as bisphenol-A (BPA), and phthalates, are commonly found in plastic wares. Exposure to these compounds poses major risk to human health because of the potential to cause endocrine disruption. There is huge demand for a wide range of chemicals to be assessed for such potential for the sake of public health. Classical in vivo assays for endocrine disruption are comprehensive but time-consuming and require sacrifice of experimental animals. Simple preliminary in vitro screening assays can reduce the time and expense involved. We previously demonstrated that catechol-O-methyltransferase (COMT) is transcriptionally regulated by estrogen via estrogen receptor (ER). Therefore, detecting corresponding changes of COMT expression in estrogen-responsive cells may be a useful method to estimate estrogenic effects of various compounds. We developed a novel cell-based ELISA to evaluate cellular response to estrogenicity by reduction of soluble-COMT expression in ER-positive MCF-7 cells exposed to estrogenic compounds. In contrast to various existing methods that only detect bioactivity, this method elucidates direct physiological effect in a living cell in response to a compound. We validated our assay using three well-characterized estrogenic plasticizers - BPA, benzyl butyl phthalate (BBP), and di-n-butyl phthalate (DBP). Cells were exposed to either these plasticizers or 17β-estradiol (E2) in estrogen-depleted medium with or without an ER-antagonist, ICI 182,780, and COMT expression assayed. Exposure to each of these plasticizers (10^-9-10^-7M) dose-dependently reduced COMT expression (p<0.05), which was blocked by ICI 182,780. Reduction of COMT expression was readily detectable in cells exposed to picomolar level of E2, comparable to other in vitro assays of similar sensitivity. To satisfy the demand for in vitro assays targeting different cellular components, a cell-based COMT assay provides useful initial screening to supplement the current assessments of xenoestrogens for potential estrogenic activity.

A non-comparative assessment of tolerability and efficacy of duloxetine in the treatment of depressed patients with Parkinson's disease

OBJECTIVE

Depression is a comorbidity affecting quality of life (QoL) in patients with Parkinson's disease (PD) and requires appropriate treatment. This study evaluated the tolerability, safety, and efficacy of duloxetine 60 mg once daily for 12 weeks in PD patients with major depressive disorder (MDD).

RESEARCH AND DESIGN METHODS

Non-comparative, open-label, multi-center study.

MAIN OUTCOME MEASURES

Tolerability was evaluated by discontinuation rate (acceptable if ≤ 19%) due to treatment-emergent adverse events (TEAEs) and motor symptoms (UPDRS). Safety measures were TEAEs, the UKU side effect rating scale, vital signs, weight, laboratory tests, and ECG. Efficacy measures included HAMD-17, BDI, CGI-S, PGI-I, and pain VAS. QoL was measured by PDQ-39.

RESULTS

Of the 151 patients enrolled, 8.6% (95% upper CI: 13.3%) discontinued the study due to TEAEs. Worsening in PD-related tremor and rigidity was not observed, activities of daily living significantly improved and UKU subscales progressively decreased. Clinically significant abnormalities in laboratory findings were limited to four cases of hypercholesterolemia and one increase of total bilirubin, CPK, and fasting glucose. Blood pressure, weight, and ECG did not change from baseline. HAMD-17 and PDQ-39 total score and individual domains, BDI, CGI-S, and PGI-I total scores significantly improved.

CONCLUSIONS

Duloxetine seems well tolerated and likely effective in the treatment of depression associated with PD, with no detrimental effects in PD signs and symptoms.

Pharmacophore modeling and virtual screening studies to design potential COMT inhibitors as new leads

Catechol-O-methyltransferase (COMT) catalyzes the methylation of catecholamines, including neurotransmitters like dopamine, epinephrine and norepinephrine, leading to their degradation. COMT has been a subject of study for its implications in numerous neurological disorders like Parkinson's disease (PD), schizophrenia, and depression. The COMT gene is associated with many allelic variants, the Val108Met polymorphism being the most clinically significant. Availability of crystal structure of both 108V and 108M forms of human soluble-COMT (S-COMT) facilitated us to use structure-based virtual screening approach to obtain new hits by screening a library of CNS permeable compounds from ZINC database. In this study, E-pharmacophore was also used to generate pharmacophore models based on a series of known COMT inhibitors. A five-point pharmacophore model consisting of one hydrogen-bond acceptor (A), two hydrogen bond donors (D), and two aromatic rings (R) was generated for both the polymorphic forms of COMT. These models were then used for filtering ZINC-CNS permeable library to obtain new hits. Physicochemical properties were also calculated for all the hits obtained from both the approaches for favorable ADME properties. These identified hits maybe of interest for further structural optimization and biological evaluation assays.

Nonmotor symptoms in Parkinson's disease in 2012: relevant clinical aspects

Nonmotor symptoms (NMSs) of Parkinson's disease (PD) are common, but they are often underrecognized in clinical practice, because of the lack of spontaneous complaints by the patients, and partly because of the absence of systematic questioning by the consulting physician. However, valid specific instruments for identification and assessment of these symptoms are available in 2012. The administration of the self-completed screening tool, NMSQuest, associated with questioning during the consultation, improves the diagnosis of NMSs. NMSs play a large role in degradation of quality of life. More relevant NMSs are described in this review, mood disorders, impulse control disorders, cognitive deficits, hallucinations, pain, sleep disorders, and dysautonomia.

Striatal mechanisms underlying movement, reinforcement, and punishment

Direct and indirect pathway striatal neurons are known to exert opposing control over motor output. In this review, we discuss a hypothetical extension of this framework, in which direct pathway striatal neurons also mediate reinforcement and reward, and indirect pathway neurons mediate punishment and aversion.

Apathy and anhedonia in Parkinson's disease

Depression, apathy, and anhedonia are often comorbid in patients with Parkinson's disease. Since the morbid states of apathy and anhedonia are complicated, these symptoms are often difficult to diagnose. Several therapeutic methods for apathy and anhedonia are considered effective. However, the validity of these methods has not been established. Similar to depression, apathy and anhedonia clearly affect the quality of life of patients and their families. Therefore, accurate diagnoses of morbid states in the early stage of the disease and corresponding appropriate treatments should be given high priority.

The relationship between depression and regional cerebral blood flow in Parkinson's disease and the effect of selegiline treatment

OBJECTIVES

We examined the relationship between severity of depression in Parkinson's disease (PD) and regional cerebral blood flow (rCBF) using single photon emission computed tomography (SPECT) and the reaction to levodopa-selegiline combination therapy.

MATERIALS AND METHODS

We evaluated 52 patients with PD and nine age-matched controls with SPECT and the Unified Parkinson's Disease Rating Scale (UPDRS) part III, Mini-Mental State Examination (MMSE), and Beck Depression Inventory (BDI) to evaluate depression severity and its connection with rCBF. Furthermore, we examined rCBF in patients with PD treated with levodopa with or without selegiline.

RESULTS

A significant fall in rCBF was observed in the bilateral posterior cingulate, hippocampus, and cuneus and the superior parietal and primary visual areas in PD patients with minor depression and in all regions in those with major depression. Elevations in UPDRS part III and BDI scores and falls in MMSE scores were of significantly lower magnitude in the levodopa-selegiline group than in the levodopa group. Whole brain rCBF fell significantly less in the levodopa-selegiline group than in the levodopa group.

CONCLUSIONS

These results indicate that selegiline controlled not only worsening of motor function and cognitive function in PD but also aggravation of minor depression, and restrained a fall in whole brain rCBF.

Paroxetine prevents loss of nigrostriatal dopaminergic neurons by inhibiting brain inflammation and oxidative stress in an experimental model of Parkinson's disease

The present study examined whether the antidepressant paroxetine promotes the survival of nigrostriatal dopaminergic (DA) neurons in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson's disease. MPTP induced degeneration of nigrostriatal DA neurons and glial activation as visualized by tyrosine hydroxylase, macrophage Ag complex-1, and/or glial fibrillary acidic protein immunoreactivity. Real-time PCR, Western blotting, and immunohistochemistry showed upregulation of proinflammatory cytokines, activation of microglial NADPH oxidase and astroglial myeloperoxidase, and subsequent reactive oxygen species production and oxidative DNA damage in the MPTP-treated substantia nigra. Treatment with paroxetine prevented degeneration of nigrostriatal DA neurons, increased striatal dopamine levels, and improved motor function. This neuroprotection afforded by paroxetine was associated with the suppression of astroglial myeloperoxidase expression and/or NADPH oxidase-derived reactive oxygen species production and reduced expression of proinflammatory cytokines, including IL-1beta, TNF-alpha, and inducible NO synthase, by activated microglia. The present findings show that paroxetine may possess anti-inflammatory properties and inhibit glial activation-mediated oxidative stress, suggesting that paroxetine and its analogues may have therapeutic value in the treatment of aspects of Parkinson's disease related to neuroinflammation.

rTMS treatment for depression in Parkinson's disease increases BOLD responses in the left prefrontal cortex

The mechanisms underlying the effects of antidepressant treatment in patients with Parkinson's disease (PD) are unclear. The neural changes after successful therapy investigated by neuroimaging methods can give insights into the mechanisms of action related to a specific treatment choice. To study the mechanisms of neural modulation of repetitive transcranial magnetic stimulation (rTMS) and fluoxetine, 21 PD depressed patients were randomized into only two active treatment groups for 4 wk: active rTMS over left dorsolateral prefrontal cortex (DLPFC) (5 Hz rTMS; 120% motor threshold) with placebo pill and sham rTMS with fluoxetine 20 mg/d. Event-related functional magnetic resonance imaging (fMRI) with emotional stimuli was performed before and after treatment - in two sessions (test and re-test) at each time-point. The two groups of treatment had a significant, similar mood improvement. After rTMS treatment, there were brain activity decreases in left fusiform gyrus, cerebellum and right DLPFC and brain activity increases in left DLPFC and anterior cingulate gyrus compared to baseline. In contrast, after fluoxetine treatment, there were brain activity increases in right premotor and right medial prefrontal cortex. There was a significant interaction effect between groups vs. time in the left medial prefrontal cortex, suggesting that the activity in this area changed differently in the two treatment groups. Our findings show that antidepressant effects of rTMS and fluoxetine in PD are associated with changes in different areas of the depression-related neural network.

Safety and tolerability of adjunctive tolcapone treatment in patients with early Parkinson's disease

OBJECTIVE

The safety and tolerability of adjunctive tolcapone initiated simultaneously with levodopa was evaluated with a focus on increases in liver transaminase and hepatotoxicity.

METHODS

677 levodopa-naïve patients with early stage Parkinson's disease (PD) were randomised to receive placebo or tolcapone 100 mg three times daily, added to standard doses of levodopa plus carbidopa or benserazide.

RESULTS

Increases in liver transaminase above the upper limit of normal (ULN) occurred in 69/342 (20.2%) and 92/335 (27.5%) patients in the placebo and tolcapone groups, respectively. Increases > or = 3 times the ULN occurred in 4/342 (1.2%) and 6/335 (1.8%) patients receiving placebo and tolcapone, respectively (p = 0.5). Liver transaminase values returned to normal in 65% of placebo and 80% of tolcapone treated patients. No instances of serious hepatotoxicity were seen. Diarrhoea was the most commonly reported AE-36/342 (11.0%) placebo v 98/335 (29.0%) tolcapone-and caused discontinuation in 9.9% of tolcapone treated patients. Overall, study discontinuation due to adverse effects was 2.9% in the placebo group and 17.3% in the tolcapone group.

CONCLUSIONS

Tolcapone seemed to be safe and was generally well tolerated as an adjunctive treatment in patients starting treatment with carbidopa/levodopa for symptomatic PD. Mild increases in transaminase levels--< 3 times the ULN--occurred commonly in both placebo and tolcapone treated patients, whereas potentially serious increases of up to > or = 3 times the ULN were infrequent.

Parkinson's disease and antidepressant drug treatment: a case-register study

We estimated the nationwide prevalence rate of antidepressant drug treatment in Parkinson's disease (PD) patients.

BACKGROUND

Very few studies exist on the frequency of antidepressant drug treatment in patients with PD.

METHOD

Patients with a PD diagnosis at first hospital contact were identified and followed for up to 6 years. The subsequent probability of antidepressant drug treatment was estimated and compared to a control group of patients with osteoarthritis.

RESULTS

The probability of antidepressant drug treatment was 3.98 [95% CI: 3.23-4.91) times higher for PD patients than for controls.

CONCLUSION

Patients with PD have higher rates of actual antidepressant drug treatment than a control group with osteoarthritis. Still, however, undertreatment of depressive states may be the case.

Depressivität und Depression bei der Parkinson-Erkrankung

Zusammenfassung: Ein erheblicher Anteil an Patienten mit einer idiopathischen Parkinson-Erkrankung (PD) entwickelt im Verlauf eine sekundäre Depression. Die Prävalenzraten schwanken erheblich, da die Diagnosestellung aufgrund von Symptomüberschneidungen zwischen neurologischer Grunderkrankung und Major Depression (MD) erschwert ist. Dies führt zu Problemen bei der therapeutischen Indikationsstellung sowie zu einer eingeschränkten Interpretierbarkeit neuropsychologischer und neurophysiologischer Studien. Ein weiterer Aspekt bezieht sich auf Gemeinsamkeiten und Unterschiede zwischen sekundärer und primärer Depression. Entgegen dem klinischen Eindruck einer PD-spezifischen Depression erbrachten psychometrische Verfahren zur Depressionsdiagnostik diesbezüglich bisher nur unbefriedigende Ergebnisse. Ziele dieses Überblicksartikels: 1. Charakterisierung depressiver Syndrome bei der PD, 2. Überblick über den Forschungsstand zur Neuropathologie und Neuropsychologie, 3. Gegenüberstellung klinisch- und/oder neuropsychologischer Gemeinsamkeiten/Unterschiede zwischen sekundärer und primärer MD und 4. Konsequenzen für Forschung und Differenzialdiagnostik.

Management of sleep problems in Parkinson's disease

Patients with Parkinson's disease (PD) frequently complain of sleep problems. These can be due to several factors, and the approach to their management depends on careful consideration of the various possible factors in each case. 1. Older people, in general, require less sleep. After retirement, people may also engage in less physical activity, and this factor is of course even more pronounced in patients with PD because of their illness. 2. Daytime naps, either spontaneous or due to drugs, reduce the need for nocturnal sleep. Explanation of these physiological and circumstantial changes may help those PD patients who manifest these consequences. 3. The existence of a severe progressive disease as well as social isolation have psychologic consequences, such as anxiety and depression, that may manifest as insomnia. Furthermore, depression is part of the disease, frequently antedating the motor manifestations, and may manifest as insomnia. 4. In advanced disease, patients may be immobile and have difficulty in getting up or even turning in bed. This causes great inconvenience, and may impair sleep. Long acting anti-Parkinson drugs such as cabergoline or rotigotine patch may help. 5. In some cases, unpleasant hallucinations may appear which prevent the patient from falling asleep. These may respond to atypical neuroleptics. Clozapine and quetiapine are particularly useful, but require attention to possible adverse effects.

Depression predicts the pattern of cognitive impairment in early Parkinson's disease

OBJECTIVE

To estimate the pattern of cognitive impairment in early Parkinson's disease (PD) associated with depression. Also, the prediction of potentially relevant demographic/clinical factors in early PD on cognitive functioning was tested.

METHOD

The study comprised 80 consecutive early PD patients (16 with major depression (PDMD), 10 PD patients with dysthimic disorder (PDDD), and 54 nondepressed PD patients (PDND)). Thirty_seven healthy subjects matched for age, gender and education were also included in the study. The cognitive evaluation included the comprehensive classical neuropsychological battery and the Cambridge Neuropsychological Test Automated Battery (CANTAB).

RESULTS

The two different patterns of cognitive impairment in early PD patients were obtained even when the confounding influences of general cognitive abilities and motor slowness were taken in account. One pattern was common to all PD patients either they were depressed or not, and it is conceived etiologically as dysexecutive. The PDDD group presented only the quantitative increment of the common deficit observed in PD. The second pattern was present in PDMD patients, involved episodic/working memory and language deficits alongside with background executive impairment. Depression was extensively associated with the cognitive dysfunction in early PD, whereas severity of the disease, age at onset and treatment were less favorable as predictors.

CONCLUSIONS

This study provides evidence that the pattern of cognitive impairment in early PD may be predicted by depression severity. Therefore, the recognition and treatment of depressive disorder in early PD is important.

Late-life depression: a neuropsychiatric approach

Late-life depression refers to depressive syndromes defined in the American Psychiatric Association's Diagnostic and Statistical Manual and in the International Classification of Diseases that arise in adults older than 65 years of age. Late life depressive syndromes often arise in the context of medical and neurologic disorders. There is a high prevalence of depression in various neurodegenerative disorders such as Alzheimer's disease, Lewy body disease, Parkinson's disease, cerebrovascular disease and frontotemporal dementias. It has been well recognized that late life depression may itself be the presenting symptom of a latent neurodegenerative disorder. Therefore, an accurate diagnosis of late-onset depression may serve to identify a high-risk group that would benefit from initiation of therapies with the goal of delaying or possibly even preventing the onset of dementia.

Response to 4-month treatment with reboxetine in Parkinson's disease patients with a major depressive episode

OBJECTIVE

The aim of this study is to evaluate response to reboxetine in a 4-month follow-up study on depression in Parkinson's disease (PD), and to assess its tolerability profile.

METHODS

A prospective 4-month follow-up study was performed in 17 PD patients with a major depressive episode. The intensity of depressive symptoms was evaluated mainly with the Hamilton Rating Scale for Depression (HAM-D), and PD was assessed with the Unified Parkinson Disease Rating Scale (UPDRS).

RESULTS

Reboxetine causes a progressive decrease in depressive symptoms in PD patients; the initial score of 16.76 (2.68) on HAM-D decreased to 5.85 (2.42) at 4 months (P < .002). Mean UPDRS scores did not show a statistically significant increase: 18.18 (2.6) at the beginning and 18.25 (2.4) at the end of the follow-up period (P = .8).

CONCLUSIONS

Reboxetine, as first choice treatment for major depressive episodes in PD patients, seems to be effective in progressively improving depressive symptoms over the first 4 months of treatment until complete remission. Reboxetine does not seem to increase PD symptoms, whereas patients' quality of life improves.

Major depression and the synthetic enhancer substances, (-)-deprenyl and R-(-)-1-(benzofuran-2-yl)-2-propylaminopentane

Because of the high number of therapy-resistant depressions and the growing number of suicides, there is still a great need for the development of antidepressants with a new pharmacological spectrum. The finding that phenylethylamine and tryptamine are endogenous enhancers of the impulse propagation mediated release of catecholamines and serotonin in the brain, and the development of synthetic enhancer substances opened the possibility to stimulate catecholaminergic and serotonergic neurons in the brain stem via a previously unknown mechanism. (-)-Deprenyl, a prototype of the phenylethylamine-derived synthetic enhancer substances, stimulates the catecholaminergic neurons in the brain but is almost ineffective on the serotonergic neurons. R-(-)-1-(benzofuran-2-yl)-2-propylaminopentane, (-)-BPAP, the recently developed tryptamine-derived selective synthetic enhancer substance, is a hundred times more potent enhancer of the catecholaminergic neuronal activity than (-)-deprenyl, and is also a highly potent stimulant of the serotonergic neurons. Evaluation of the peculiar pharmacological profile, the high potency and unusual safeness and tolerability of (-)-BPAP cherish the hope that this compound by itself and in combination with uptake inhibitors may improve the effectiveness of drug therapy in major depression and diminish the number of therapy resistant cases.

Minor depression and brain perfusion images in Parkinson's disease

Depression is common in individuals with Parkinson's disease. However, the pathophysiology of depression in Parkinson's disease remains obscure. Here we compared brain perfusion images of Parkinson's disease patients with and without depression to investigate correlations between depression and brain perfusion images in Parkinson's disease. We divided 40 consecutive patients with Parkinson's disease into two groups: patients with minor depression (n = 22) and patients without depression (n = 18). We then compared brain perfusion images between the two groups. As a result, hypoperfusion of the left superior and inferior frontal gyrus was demonstrated in depressed patients. These results were partially in agreement with previous studies on de novo and parkinsonian major depression. We could not conclude on whether pathophysiological mechanisms differed between de novo depression and depression with Parkinson's disease, and between major and minor depressions.

Antidepressant-like effects of selegiline in the forced swim test

Although selegiline, a monoamine oxidase (MAO)-B inhibitor, is reported to exert antidepressant effects in depressant patients, evidence in rodents for effects of selegiline is quite limited. The purpose of the present study was to assess effects of selegiline in the forced swim test (FST) and on locomotor activity, and to investigate whether MAO inhibition or stimulation of receptors contributes to antidepressant-like effects of selegiline. Drugs were subcutaneously administrated. The single administration of reference drug nortriptyline at 5 mg/kg reduced locomotor activity without effects in FST and brain MAO activities. But nortriptyline repeatedly given 24, 5 and 1 h before behavioral tests significantly decreased an immobility time in FST without effects in motor activities, and showed weak brain MAO-B inhibition. Single and following repeated (24, 5 and 1 h before behavioral tests) administrations of selegiline at 10 mg/kg significantly decreased the immobility time in FST, with little motor stimulant effect. In contrast, (+)-methamphetamine caused a marked decrease in immobility time and an increase in locomotor activity. Selegiline at 1 and 3 mg/kg, which failed to decrease immobility time, markedly inhibited brain total-MAO and MAO-B activities. A dopamine D1 receptor antagonist SCH 23390 completely blocked antidepressant-like effects of selegiline, but not dopamine D2, serotonergic or noradrenergic receptor antagonists. These results suggest that selegiline exerts the antidepressant-like effects by prolonging escape-directed behavior rather than by a motor stimulant effect and D1 receptor activation contributes to its effect.

Gender and the Parkinson's disease phenotype

OBJECTIVES

To determine whether there are gender differences in the Parkinson's disease (PD) phenotype using a large clinic-based cohort.

METHODS

We examined gender differences in demographic, historical and clinical characteristics in a consecutive clinical series of 1,264 individuals diagnosed with PD.

RESULTS

The majority of individuals in the sample were male (67 %). Comparative analyses showed males and females were not significantly different on most demographic and historical characteristics. For both genders, the mean age and the mean age at symptomatic onset were about 70 and 63 years, respectively and, thus, disease duration was not significantly different between genders. The proportion of individuals with a positive family history of PD (15 %) was similar for both genders. A positive history of depression was significantly higher in females (35 % vs. 24 %). The UPDRS instability score was significantly worse among females, whereas the rigidity score was significantly worse for males. Females showed significantly worse ADL capacity and a more advanced H&Y stage. The proportion of individuals receiving antiparkinsonian medication (about 66 %) and time between the last dose and the clinical evaluation (about 4 hours) was similar for both genders. There was a trend for lower daily levodopa equivalence dosage and more severe dyskinesia score among females but these differences did not reach statistical significance after Bonferroni correction.

CONCLUSIONS

The majority of comparisons tended to highlight the commonalities in the PD phenotype between genders, particularly in reference to historical and early disease stage characteristics. However, gender may be an important factor related to the expression of PD features during the symptomatic disease course.

Depression in Parkinson's disease: loss of dopamine and noradrenaline innervation in the limbic system

The reason for the high frequency of depression and anxiety in Parkinson's disease is poorly understood. Degeneration of neurotransmitter systems other than dopamine might play a specific role in the occurrence of these affective disorders. We used [11C]RTI-32 PET, an in vivo marker of both dopamine and noradrenaline transporter binding, to localize differences between depressed and non-depressed patients. We studied eight and 12 Parkinson's disease patients with and without a history of depression matched for age, disease duration and doses of antiparkinsonian medication. The depressed Parkinson's disease cohort had lower [11C]RTI-32 binding than non-depressed Parkinson's disease cases in the locus coeruleus and in several regions of the limbic system including the anterior cingulate cortex, the thalamus, the amygdala and the ventral striatum. Exploratory analyses revealed that the severity of anxiety in the Parkinson's disease patients was inversely correlated with the [11C]RTI-32 binding in most of these regions and apathy was inversely correlated with [11C]RTI-32 binding in the ventral striatum. These results suggest that depression and anxiety in Parkinson's disease might be associated with a specific loss of dopamine and noradrenaline innervation in the limbic system.

Pharmacological studies with endogenous enhancer substances: beta-phenylethylamine, tryptamine, and their synthetic derivatives

The discovery of enhancer regulation in the mesencephalon and the concept that it plays a key role in the operation of innate and acquired drives [Neurochem. Res. 28 (2003) 1187] sets the trace amines (TAs) in their true physiological perspective. The regulation is defined as the existence of enhancer-sensitive neurons in the brain capable of working in a split-second on a high activity level due to endogenous enhancer substances. For the time being, only beta-phenylethylamine (PEA) and tryptamine are the experimentally analyzed examples. (-)-Deprenyl (selegiline), widely used in Parkinson's disease and Alzheimer's disease today, and known as the first selective monoamine oxidase (MAO) type-B inhibitor for decades, was identified as a PEA-derived synthetic mesencephalic enhancer substance. An important and convincing confirmation of the enhancer concept was the recent development of a highly specific and potent tryptamine-derived synthetic mesencephalic enhancer substance, (-)-1-(benzofuran-2-yl)-2-propylaminopentane [(-)-BPAP]. This substance, which is specific and hundreds of times more potent than selegiline, is now the best experimental tool to study the enhancer regulation in the mesencephalon and a promising candidate to significantly surpass the therapeutic efficiency of selegiline in depression, Parkinson's disease, and Alzheimer's disease.

Psychiatric comorbidity in a population of Parkinson's disease patients

Behavioural disturbances are frequently observed in Parkinson's disease (PD), including mood and anxiety disorders. The existence of a comorbidity between such psychiatric disorders in PD patients has been suggested only in a few studies. To assess the prevalence of mood and anxiety disturbances, and the rate of comorbidity of such disorders in PD. Secondary aim was to correlate the prevalence of psychiatric disorders in PD with age, sex, laterality of motor symptomatology, clinical features, severity of disease, age of onset and PD duration, and anti-parkinsonian therapy. Ninety consecutive PD outpatients, and 90 age- and sex-matched controls were included. All PD patients enrolled were non-fluctuating (21 de novo, 69 treated with levodopa or dopamine agonists). PD patients and controls with Mini Mental State Examination score <23 were excluded. Psychiatric diagnosis was performed by semistructured interview according with DSM-IV criteria and the severity of depressive and anxious symptoms was rated with clinical rating scales. Major depression was found in 21.1% PD patients vs. 3.3% controls (P < 0.01, chi-square analysis), dystimia in 18.8% PD patients vs. 4.4% controls (P < 0.05), panic disorders in 30% PD patients vs. 5.5% controls (P < 0.01). No difference in the prevalence of other anxiety disorders was observed between the two groups. The comorbidity of mood and anxiety disorders was found in 19.3% PD patients vs. 8.6% controls (P < 0.01). No correlation was reported between the prevalence of behavioural disturbances and any of the demographic, clinical or pharmacological data taken into account. Our findings might suggest the existence of a wide spectrum of psychiatric disorders in PD ranging from pure depressive disorders, comorbid depressive and anxiety disorders, and pure anxiety disorders, presumably linked to the same neurobiological substrate.

Depression in Parkinson's disease: clinical correlates and outcome

Depression has been shown to be more common in Parkinson's disease (PD) than in other chronic and disabling disorders. Neurochemical and functional disturbances are important etiopathogenic factors. The prevalence and clinical features associated with depression in PD remain controversial. The purpose of this study is to estimate the prevalence of depressive symptoms in our patients, as related to other clinical data, and to assess clinical outcomes of these symptoms. A series of PD patients were evaluated over a 9-year period, using the Unified Parkinson's Disease Rating Scale (UPDRS), Hoehn and Yahr stage (HY), Schwab and England Scale (SE), Mini-Mental State Examination (MMSE), and Yesavage Geriatric Depression Scale (GDS). Presence of depressive symptoms was considered if GDS score was higher than 10: mild-moderate (MD) for GDS scores between 11 and 20 and moderate-severe (SD) for GDS scores greater than 20. Three hundred and fifty-three patients were included in this study and additional follow up information was obtained for 184 patients. MD and SD were found in 40.2 and 16.7% of PD patients, respectively. Female gender, high HY, high UPDRS total and subtotal, and low MMSE and SE scores were significantly associated with depressive symptoms. According to changes in GDS score, 34% of patients remained stable, 35% showed an improvement, and 30.9% worsened in the follow up study. Gender, age, age of onset, HY, UPDRS, and PD duration are not related to depression outcome.

Depression and Parkinson's disease: a new look at an old problem

A National Institutes of Health (National Institute of Neurological Disorders and Stroke; National Institute of Mental Health; National Institute on Aging) working group meeting focused on the non-motor aspects of Parkinson's disease (PD). Below is the summary of the meeting presentations and recommendations for a research agenda on the epidemiology, assessment, circuitry, therapeutic approaches, and clinical trials of Parkinson's disease co-morbid with depression. A second summary will focus on PD and dementia.

The importance of educational and psychological factors in Parkinson's disease quality of life

OBJECTIVE

To define the factors correlated with quality of life (QoL) in patients with idiopathic Parkinson's disease (PD).

BACKGROUND

PD has a substantial impact on QoL. Although several clinical factors have been associated with QoL in PD, the influence of patient's education still remains controversial.

METHODOLOGY

A consecutive series of patients with PD were examined using the unified Parkinson's Disease Rating Scale (UPDRS part I, II, III), Schwab and England (SE), and Hoehn and Yahr stage (H&Y). QoL was rated with the PDQ-39, cognition with the Mini-Mental State examination (MMSE), and the presence of depressive symptoms with the geriatric depression scale (GDS). Patient's characteristics, estimated cumulative levodopa dose (CLD), UPDRS, H&Y, MMSE and GDS were correlated with the PDQ-39 using univariate and multiple regression analysis.

RESULTS

A total of one hundred 58 patients (68 men, 90 women) with a mean age of 65.6 +/- 9.3 years, PD duration of 8.1 +/- 10.6 years, and education of 6.6 +/- 3.9 years were included. The mean PDQ-39 was 48.8 +/- 27.8, mean MMSE was 25.7 +/- 4, and mean GDS was 11.7 +/- 6.8. Using stepwise multiple regression analysis, the most important predictive factors were depression, UPDRS part I, UPDRS part II, and educational background, which accounted for a 61% of the variability of the PDQ-39 scores.

CONCLUSIONS

In our PD sample, educational, behavioural, and psychological factors influenced life satisfaction more than physical ones.

Major depressive disorder in Parkinson's disease: a register-based study

OBJECTIVE

To investigate whether patients with Parkinson's disease (PD) were at an increased risk of developing major depression compared with patients having other medical illnesses with a comparable degree of disability.

METHOD

Case register linkage study of Danish Psychiatric Central Register (DPCR)and Danish National Hospital Register (DNHR). Three study cohorts were identified: all patients with PD, osteoarthritis, and diabetes. The rate of discharge diagnosis of depression on re-admission was estimated using competing risks models in survival analyses. The rates for patients with PD were compared with those of patients with osteoarthritis, and diabetes.

RESULTS

The study sample identified 211 245 patients in the hospital registers with one of the index diagnoses. An increased incidence of developing depression was found for women and men throughout their lifetime when this incidence was compared with the control groups.

CONCLUSION

The findings support the hypothesis that depression in patients with PD is a consequence of brain dysfunction.

Therapeutic efficacy of bilateral prefrontal slow repetitive transcranial magnetic stimulation in depressed patients with Parkinson's disease: an open study

Recent studies have suggested that both high- and low-frequency repetitive transcranial magnetic stimulation (rTMS) have antidepressant effects in patients with major depression. We conducted an open study to assess the effects of slow rTMS on mood changes in patients with depression associated with Parkinson's disease (PD). Ten depressed patients with PD (four with major depression and six with dysthymia) received daily sessions of rTMS (frequency, 0.5 Hz; pulse duration, 0.1 msec; field intensity, 10% above the motor threshold) over both prefrontal regions (a total of 100 stimuli per prefrontal region daily) over 10 consecutive days. This treatment resulted in a moderate but significant decrease in scores of the Hamilton Depression Rating Scale (33-37%) and the Beck Depression Inventory (24-34%), which persisted 20 days after finishing the stimulation. In parallel, we observed mild improvement (18-20%) of motor symptoms. No significant adverse effects were reported. These preliminary results suggest the therapeutic potential of daily prefrontal low-frequency rTMS (0.5 Hz) in depression associated with PD.

Drug treatment of non-motor symptoms in Parkinson's disease

Non-motor symptoms may considerably reduce parkinsonian quality of life, particularly in advanced stages of the disease. Autonomic features, such as seborrhoea, hyperhidrosis, orthostatic hypotension, excessive salivation, bladder dysfunction and GI disturbances, and neuropsychiatric symptoms, such as depression, sleep disorders, psychosis and dementia, appear in the course of Parkinson's disease. Pharmacotherapy of these non-motor symptoms complicates long-term antiparkinsonian combination drug therapy due to possible drug interactions, side effects and changes in metabolism. Moreover, antiparkinsonian compounds themselves contribute to the onset of these non-motor symptoms to a considerable extent. This complicates differentiation between the disease process itself and drug-related effects, thus influencing therapeutic options, which are often limited because of comorbidity and polypharmacy. Therefore, standardised recommendations are questionable, since drug tolerability and response differ between patients. Nevertheless, this review tries to provide a survey of possible therapeutic options for the treatment of the symptoms of Parkinson's disease other the dopamine-sensitive motor features.

Novel monoamine oxidase inhibitors, 3-(2-aminoethoxy)-1,2-benzisoxazole derivatives, and their differential reversibility

Although possible usefulness of non-selective monoamine oxidase (MAO) inhibitors for Parkinson's disease therapy has been suggested in the literature, MAO inhibitors whose inhibition is reversible and have dual action to both MAO-A and -B subtypes is not available yet. Subtype selectivity and reversibility of a series of novel MAO inhibitors, 3-(2-aminoethoxy)-1,2-benzisoxazole derivatives, were studied. Several dual MAO inhibitors, which inhibit both MAO-A and -B, were obtained. When administered to mice, their effects were generally reversible. Among the derivatives, RS-1636 and RS-1653 had much longer duration of brain MAO-B inhibition than that of MAO-A. In vitro, the inhibited MAO-A activity by these compounds was partially recovered by buffer change at 4 degrees C, while little MAO-B activity was recovered. Although it is not fully elucidated yet, the reversibility of these inhibitors is probably determined primarily by this dissociation profile. This unique differential reversibility indicates that optimization of the balance of actions can be achieved by differentiating reversibility to each target molecule.

Changes in endogenous monoamines in aged rats

1. It has been documented that ageing may alter endogenous neurotransmitters. However, these results are controversial. Thus, in the present study, cerebral cortex and plasma from male Wistar rats aged 8 weeks and 6, 12 or 24 months were used to investigate the changes in monoamines using electrochemical detection. 2. A marked decrease in L-dihydroxyphenylalanine (L-DOPA) was observed in aged rats. Like the decrease in dopamine (DA), levels of 5-hydroxytryptamine (5-HT) and 5-hydroxyindolacetic acid (5-HIAA), the major metabolite of 5-HT, in aged rats were decreased in the cerebral cortex and plasma. Plasma levels of noradrenaline and levels of adrenaline in the cerebral cortex were also decreased in aged rats. Moreover, levels of 3,4-dihydroxyphenylacetic acid (DOPAC), a metabolite of DA, in the cerebral cortex and plasma were reduced by ageing. The level of homovanillic acid (HVA) in all samples was markedly increased with ageing. 3. The ratio of DOPAC/DA and 5-HIAA/5-HT, being closely linked with the activity of monoamine oxidase, was increased in the cerebral cortex and plasma with ageing. The ratio of HVA/DOPAC, an index of the activity of catechol-O-methyltransferase, was also higher in the cerebral cortex and plasma of aged rats. 4. These data suggest that ageing may alter endogenous monoamines in both the brain and peripheral tissues.