Cognitive phenotype and neurodegeneration associated with Tau in Huntington's disease

OBJECTIVE

The clinical phenotype of Huntington's disease (HD) can be very heterogeneous between patients, even when they share equivalent CAG repeat length, age, or disease burden. This heterogeneity is especially evident in terms of the cognitive profile and related brain changes. To shed light on the mechanisms participating in this heterogeneity, the present study delves into the association between Tau pathology and more severe cognitive phenotypes and brain damage in HD.

METHODS

We used a comprehensive neuropsychological examination to characterize the cognitive phenotype of a sample of 30 participants with early-to-middle HD for which we also obtained 3 T structural magnetic resonance image (MRI) and cerebrospinal fluid (CSF). We quantified CSF levels of neurofilament light chain (NfL), total Tau (tTau), and phosphorylated Tau-231 (pTau-231). Thanks to the cognitive characterization carried out, we subsequently explored the relationship between different levels of biomarkers, the cognitive phenotype, and brain integrity.

RESULTS

The results confirmed that more severe forms of cognitive deterioration in HD extend beyond executive dysfunction and affect processes with clear posterior-cortical dependence. This phenotype was in turn associated with higher CSF levels of tTau and pTau-231 and to a more pronounced pattern of posterior-cortical atrophy in specific brain regions closely linked to the cognitive processes affected by Tau.

INTERPRETATION

Our findings reinforce the association between Tau pathology, cognition, and neurodegeneration in HD, emphasizing the need to explore the role of Tau in the cognitive heterogeneity of the disease.

Cerebrospinal Fluid Flow in Patients with Huntington's Disease

OBJECTIVE

Investigations of cerebrospinal fluid (CSF) flow aberrations in Huntington's disease (HD) are of growing interest, as impaired CSF flow may contribute to mutant Huntington retention and observed heterogeneous responsiveness to intrathecally administered therapies.

METHOD

We assessed net cerebral aqueduct CSF flow and velocity in 29 HD participants (17 premanifest and 12 manifest) and 51 age- and sex matched non-HD control participants using 3-Tesla magnetic resonance imaging methods. Regression models were applied to test hypotheses regarding: (i) net CSF flow and cohort, (ii) net CSF flow and disease severity (CAP-score), and (iii) CSF volume after correcting for age and sex.

RESULTS

Group-wise analyses support a decrease in net CSF flow in HD (mean 0.14 ± 0.27 mL/min) relative to control (mean 0.32 ± 0.20 mL/min) participants (p = 0.02), with lowest flow in the manifest HD cohort (mean 0.04 ± 0.25 mL/min). This finding was explained by hyperdynamic CSF movement, manifesting as higher caudal systolic CSF flow velocity and higher diastolic cranial CSF flow velocity across the cardiac cycle, in HD (caudal flow: 0.17 ± 0.07 mL/s, cranial flow: 0.14 ± 0.08 mL/s) compared to control (caudal flow: 0.13 ± 0.06 mL/s, cranial flow: 0.11 ± 0.04 mL/s) participants. A positive correlation between cranial diastolic flow and disease severity was observed (p = 0.02).

INTERPRETATIONS

Findings support aqueductal CSF flow dynamics changing with disease severity in HD. These accelerated changes are consistent with changes observed over the typical adult lifespan, and may have relevance to mutant Huntington retention and intrathecally administered therapeutics responsiveness. ANN NEUROL 2023;94:885-894.

Kynurenine pathway metabolites in cerebrospinal fluid and blood as potential biomarkers in Huntington's disease

Converging lines of evidence from several models, and post-mortem human brain tissue studies, support the involvement of the kynurenine pathway (KP) in Huntington's disease (HD) pathogenesis. Quantifying KP metabolites in HD biofluids is desirable, both to study pathobiology and as a potential source of biomarkers to quantify pathway dysfunction and evaluate the biochemical impact of therapeutic interventions targeting its components. In a prospective single-site controlled cohort study with standardised collection of cerebrospinal fluid (CSF), blood, phenotypic and imaging data, we used high-performance liquid-chromatography to measure the levels of KP metabolites-tryptophan, kynurenine, kynurenic acid, 3-hydroxykynurenine, anthranilic acid and quinolinic acid-in CSF and plasma of 80 participants (20 healthy controls, 20 premanifest HD and 40 manifest HD). We investigated short-term stability, intergroup differences, associations with clinical and imaging measures and derived sample-size calculation for future studies. Overall, KP metabolites in CSF and plasma were stable over 6 weeks, displayed no significant group differences and were not associated with clinical or imaging measures. We conclude that the studied metabolites are readily and reliably quantifiable in both biofluids in controls and HD gene expansion carriers. However, we found little evidence to support a substantial derangement of the KP in HD, at least to the extent that it is reflected by the levels of the metabolites in patient-derived biofluids.

Brain-derived neurotrophic factor in cerebrospinal fluid and plasma is not a biomarker for Huntington's disease

Brain-derived neurotrophic factor (BDNF) is implicated in the survival of striatal neurons. BDNF function is reduced in Huntington's disease (HD), possibly because mutant huntingtin impairs its cortico-striatal transport, contributing to striatal neurodegeneration. The BDNF trophic pathway is a therapeutic target, and blood BDNF has been suggested as a potential biomarker for HD, but BDNF has not been quantified in cerebrospinal fluid (CSF) in HD. We quantified BDNF in CSF and plasma in the HD-CSF cohort (20 pre-manifest and 40 manifest HD mutation carriers and 20 age and gender-matched controls) using conventional ELISAs and an ultra-sensitive immunoassay. BDNF concentration was below the limit of detection of the conventional ELISAs, raising doubt about previous CSF reports in neurodegeneration. Using the ultra-sensitive method, BDNF concentration was quantifiable in all samples but did not differ between controls and HD mutation carriers in CSF or plasma, was not associated with clinical scores or MRI brain volumetric measures, and had poor ability to discriminate controls from HD mutation carriers, and premanifest from manifest HD. We conclude that BDNF in CSF and plasma is unlikely to be a biomarker of HD progression and urge caution in interpreting studies where conventional ELISA was used to quantify CSF BDNF.

Disease-related Huntingtin seeding activities in cerebrospinal fluids of Huntington's disease patients

In Huntington's disease (HD), the mutant Huntingtin (mHTT) is postulated to mediate template-based aggregation that can propagate across cells. It has been difficult to quantitatively detect such pathological seeding activities in patient biosamples, e.g. cerebrospinal fluids (CSF), and study their correlation with the disease manifestation. Here we developed a cell line expressing a domain-engineered mHTT-exon 1 reporter, which showed remarkably high sensitivity and specificity in detecting mHTT seeding species in HD patient biosamples. We showed that the seeding-competent mHTT species in HD CSF are significantly elevated upon disease onset and with the progression of neuropathological grades. Mechanistically, we showed that mHTT seeding activities in patient CSF could be ameliorated by the overexpression of chaperone DNAJB6 and by antibodies against the polyproline domain of mHTT. Together, our study developed a selective and scalable cell-based tool to investigate mHTT seeding activities in HD CSF, and demonstrated that the CSF mHTT seeding species are significantly associated with certain disease states. This seeding activity can be ameliorated by targeting specific domain or proteostatic pathway of mHTT, providing novel insights into such pathological activities.

Cerebrospinal fluid endo-lysosomal proteins as potential biomarkers for Huntington's disease

Molecular markers derived from cerebrospinal fluid (CSF) represent an accessible means of exploring the pathobiology of Huntington's disease (HD) in vivo. The endo-lysosomal/autophagy system is dysfunctional in HD, potentially contributing to disease pathogenesis and representing a potential target for therapeutic intervention. Several endo-lysosomal proteins have shown promise as biomarkers in other neurodegenerative diseases; however, they have yet to be fully explored in HD. We performed parallel reaction monitoring mass spectrometry analysis (PRM-MS) of multiple endo-lysosomal proteins in the CSF of 60 HD mutation carriers and 20 healthy controls. Using generalised linear models controlling for age and CAG, none of the 18 proteins measured displayed significant differences in concentration between HD patients and controls. This was affirmed by principal component analysis, in which no significant difference across disease stage was found in any of the three components representing lysosomal hydrolases, binding/transfer proteins and innate immune system/peripheral proteins. However, several proteins were associated with measures of disease severity and cognition: most notably amyloid precursor protein, which displayed strong correlations with composite Unified Huntington's Disease Rating Scale, UHDRS Total Functional Capacity, UHDRS Total Motor Score, Symbol Digit Modalities Test and Stroop Word Reading. We conclude that although endo-lysosomal proteins are unlikely to have value as disease state CSF biomarkers for Huntington's disease, several proteins demonstrate associations with clinical severity, thus warranting further, targeted exploration and validation in larger, longitudinal samples.

Fluid and imaging biomarkers for Huntington's disease

Huntington's disease is a chronic progressive neurodegenerative condition for which there is no disease-modifying treatment. The known genetic cause of Huntington's disease makes it possible to identify individuals destined to develop the disease and instigate treatments before the onset of symptoms. Multiple trials are already underway that target the cause of HD, yet clinical measures are often insensitive to change over typical clinical trial duration. Robust biomarkers of drug target engagement, disease severity and progression are required to evaluate the efficacy of treatments and concerted efforts are underway to achieve this. Biofluid biomarkers have potential advantages of direct quantification of biological processes at the molecular level, whilst imaging biomarkers can quantify related changes at a structural level in the brain. The most robust biofluid and imaging biomarkers can offer complementary information, providing a more comprehensive evaluation of disease stage and progression to inform clinical trial design and endpoints.

Cerebrospinal fluid sCD27 levels indicate active T cell-mediated inflammation in premanifest Huntington's disease

INTRODUCTION

Huntington's disease (HD) is a neurodegenerative disorder, but evidence also suggests neuroinflammation in the pathogenesis. The immune mechanisms involved and the timing of their activation need further clarification.

METHODS

A clinically well-characterized HD cohort and gene negative controls were enrolled. YKL-40 reflecting innate immunity and sCD27, a marker of adaptive immunity, were measured across disease stages. Comparisons were made with markers of neurodegeneration: neurofilament light (NFL), total-tau (T-tau), and phospho-tau (P-tau).

RESULTS

52 cross-sectional cerebrospinal fluid samples and 23 follow-up samples were analyzed. sCD27 was elevated in manifest HD and premanifest gene expansion carriers, whereas controls mostly had undetectable levels. YKL-40 showed a trend toward increase in manifest HD. sCD27 correlated with YKL-40 which in turn was closely associated to all included markers of neurodegeneration. YKL-40, NFL, and both forms of tau could all independently predict HD symptoms, but only NFL levels differed between groups after age-adjustment.

CONCLUSION

Increased sCD27 in premanifest HD is a sign of T cell-mediated neuroinflammation. This finding is novel since other reports almost exclusively have found early involvement of innate immunity. Validation of sCD27 in a larger HD cohort is needed. The role of adaptive immunity in HD needs further clarification, as it may hasten disease progression.

MicroRNAs in CSF as prodromal biomarkers for Huntington disease in the PREDICT-HD study

OBJECTIVE

To investigate the feasibility of microRNA (miRNA) levels in CSF as biomarkers for prodromal Huntington disease (HD).

METHODS

miRNA levels were measured in CSF from 60 PREDICT-HD study participants using the HTG protocol. Using a CAG-Age Product score, 30 prodromal HD participants were selected based on estimated probability of imminent clinical diagnosis of HD (i.e., low, medium, high; n = 10/group). For comparison, participants already diagnosed (n = 15) and healthy controls (n = 15) were also selected.

RESULTS

A total of 2,081 miRNAs were detected and 6 were significantly increased in the prodromal HD gene expansion carriers vs controls at false discovery rate q < 0.05 (miR-520f-3p, miR-135b-3p, miR-4317, miR-3928-5p, miR-8082, miR-140-5p). Evaluating the miRNA levels in each of the HD risk categories, all 6 revealed a pattern of increasing abundance from control to low risk, and from low risk to medium risk, which then leveled off from the medium to high risk and HD diagnosed groups.

CONCLUSIONS

This study reports miRNAs as CSF biomarkers of prodromal and diagnosed HD. Importantly, miRNAs were detected in the prodromal HD groups furthest from diagnosis where treatments are likely to be most consequential and meaningful. The identification of potential biomarkers in the disease prodrome may prove useful in evaluating treatments that may postpone disease onset.

CLINICALTRIALSGOV IDENTIFIER

NCT00051324.

Tau or neurofilament light-Which is the more suitable biomarker for Huntington's disease?

INTRODUCTION

Previous studies have suggested cerebrospinal fluid (CSF) levels of neurofilament light (NFL) and total tau are elevated in Huntington's disease (HD) and may be used as markers of disease stage. Biomarkers are needed due to the slow disease progression and the limitations of clinical assessment. This study aims to validate the role of NFL and tau as biomarkers in HD.

METHODS

CSF was obtained from a cohort of HD patients and premanifest HD-mutation carriers. Unified Huntington's Disease Rating Scale (UHDRS) testing was performed on all subjects at the time of sampling. NFL and tau concentrations were determined by ELISA. Spearman correlations were calculated with R version 3.2.3.

RESULTS

11 premanifest HD and 12 manifest HD subjects were enrolled. NFL and tau levels were correlated. NFL showed strong correlations with all items included in the clinical assessment (for example the total functional capacity (TFC) (r = - 0.70 p < 0.01) and total motor score (TMS) (r = 0.83p < 0.01). Tau showed slightly weaker correlations (eg. TMS (r = 0.67 p < 0.01); TFC (r = - 0.59 p < 0.01)). NFL was significantly correlated with 5-year probability of disease onset, whereas tau was not.

CONCLUSION

This study strengthens the case for NFL as a useful biomarker of disease stage. NFL was strongly correlated to all evaluated items in the UHDRS assessment. Tau also has a potential for use as a biomarker but correlations to clinical tests are weaker in this study. We suggest that NFL and possibly tau be used in clinical drug trials as biomarkers of disease progression that are potentially influenced by future disease-modifying therapies.

Cerebrospinal fluid total tau concentration predicts clinical phenotype in Huntington's disease

Huntington's disease (HD) is a hereditary neurodegenerative condition with no therapeutic intervention known to alter disease progression, but several trials are ongoing and biomarkers of disease progression are needed. Tau is an axonal protein, often altered in neurodegeneration, and recent studies pointed out its role on HD neuropathology. Our goal was to study whether cerebrospinal fluid (CSF) tau is a biomarker of disease progression in HD. After informed consent, healthy controls, pre-symptomatic and symptomatic gene expansion carriers were recruited from two HD clinics. All participants underwent assessment with the Unified HD Rating Scale '99 (UHDRS). CSF was obtained according to a standardized lumbar puncture protocol. CSF tau was quantified using enzyme-linked immunosorbent assay. Comparisons between two groups were tested using ancova. Pearson's correlation coefficients were calculated for disease progression. Significance level was defined as p < 0.05. Seventy-six participants were included in this cross-sectional multicenter international pilot study. Age-adjusted CSF tau was significantly elevated in gene expansion carriers compared with healthy controls (p = 0.002). UHDRS total functional capacity was significantly correlated with CSF tau (r = -0.29, p = 0.004) after adjustment for age, and UHDRS total motor score was significantly correlated with CSF tau after adjustment for age (r = 0.32, p = 0.002). Several UHDRS cognitive tasks were also significantly correlated with CST total tau after age-adjustment. This study confirms that CSF tau concentrations in HD gene mutation carriers are increased compared with healthy controls and reports for the first time that CSF tau concentration is associated with phenotypic variability in HD. These conclusions strengthen the case for CSF tau as a biomarker in HD. In the era of novel targeted approaches to Huntington's disease, reliable biomarkers are needed. We quantified Tau protein, a marker of neuronal death, in cerebrospinal fluid and found it was increased in patients with Huntington's disease and predicted motor, cognitive, and functional disability in patients. It is therefore likely to be a biomarker of disease progression, and possibly of therapeutic response. Read the Editorial Highlight for this article on page 9.

Robust MR-based approaches to quantifying white matter structure and structure/function alterations in Huntington's disease

BACKGROUND

Huge advances have been made in understanding and addressing confounds in diffusion MRI data to quantify white matter microstructure. However, there has been a lag in applying these advances in clinical research. Some confounds are more pronounced in HD which impedes data quality and interpretability of patient-control differences. This study presents an optimised analysis pipeline and addresses specific confounds in a HD patient cohort.

METHOD

15 HD gene-positive and 13 matched control participants were scanned on a 3T MRI system with two diffusion MRI sequences. An optimised post processing pipeline included motion, eddy current and EPI correction, rotation of the B matrix, free water elimination (FWE) and tractography analysis using an algorithm capable of reconstructing crossing fibres. The corpus callosum was examined using both a region-of-interest and a deterministic tractography approach, using both conventional diffusion tensor imaging (DTI)-based and spherical deconvolution analyses.

RESULTS

Correcting for CSF contamination significantly altered microstructural metrics and the detection of group differences. Reconstructing the corpus callosum using spherical deconvolution produced a more complete reconstruction with greater sensitivity to group differences, compared to DTI-based tractography. Tissue volume fraction (TVF) was reduced in HD participants and was more sensitive to disease burden compared to DTI metrics.

CONCLUSION

Addressing confounds in diffusion MR data results in more valid, anatomically faithful white matter tract reconstructions with reduced within-group variance. TVF is recommended as a complementary metric, providing insight into the relationship with clinical symptoms in HD not fully captured by conventional DTI metrics.

Quantification of mutant huntingtin protein in cerebrospinal fluid from Huntington's disease patients

BACKGROUND

Quantification of disease-associated proteins in the cerebrospinal fluid (CSF) has been critical for the study and treatment of several neurodegenerative disorders; however, mutant huntingtin protein (mHTT), the cause of Huntington's disease (HD), is at very low levels in CSF and, to our knowledge, has never been measured previously.

METHODS

We developed an ultrasensitive single-molecule counting (SMC) mHTT immunoassay that was used to quantify mHTT levels in CSF samples from individuals bearing the HD mutation and from control individuals in 2 independent cohorts.

RESULTS

This SMC mHTT immunoassay demonstrated high specificity for mHTT, high sensitivity with a femtomolar detection threshold, and a broad dynamic range. Analysis of the CSF samples showed that mHTT was undetectable in CSF from all controls but quantifiable in nearly all mutation carriers. The mHTT concentration in CSF was approximately 3-fold higher in patients with manifest HD than in premanifest mutation carriers. Moreover, mHTT levels increased as the disease progressed and were associated with 5-year onset probability. The mHTT concentration independently predicted cognitive and motor dysfunction. Furthermore, the level of mHTT was associated with the concentrations of tau and neurofilament light chain in the CSF, suggesting a neuronal origin for the detected mHTT.

CONCLUSIONS

We have demonstrated that mHTT can be quantified in CSF from HD patients using the described SMC mHTT immunoassay. Moreover, the level of mHTT detected is associated with proximity to disease onset and diminished cognitive and motor function. The ability to quantify CSF mHTT will facilitate the study of HD, and mHTT quantification could potentially serve as a biomarker for the development and testing of experimental mHTT-lowering therapies for HD.

TRIAL REGISTRATION

Not applicable.

FUNDING

CHDI Foundation Inc.; Medical Research Council (MRC) UK; National Institutes for Health Research (NIHR); Rosetrees Trust; Swedish Research Council; and Knut and Alice Wallenberg Foundation.

Brain structure in preclinical Huntington's disease

BACKGROUND

Huntington's disease (HD) is traditionally conceptualized as a degenerative disease of the striatum. Recent scientific advances, however, have suggested neurodevelopmental contributions and extrastriatal brain abnormalities. This study was designed to assess the morphology of the brain in participants who had previously undergone elective DNA analyses for the HD mutation who did not currently have a clinical diagnosis of HD (preclinical HD subjects).

METHODS

Twenty-four preclinical participants with the gene expansion for HD underwent brain magnetic resonance imaging and were compared with a group of 24 healthy control subjects, matched by gender and age.

RESULTS

Huntington's disease preclinical participants had substantial morphologic differences from controls throughout the cerebrum. Volume of the cerebral cortex was significantly increased in preclinical HD, whereas the basal ganglia and cerebral white matter volume were substantially decreased.

CONCLUSIONS

In individuals with the HD gene mutation who are considered healthy (preclinical for manifest disease), the morphology of the brain is substantially altered compared with matched control subjects. Although decreased volumes of the striatum and cerebral white matter could represent early degenerative changes, the novel finding of enlarged cortex suggests that developmental pathology occurs in HD.

Normal hypocretin-1 (orexin-A) levels in the cerebrospinal fluid of patients with Huntington's disease

A significant atrophy and loss of hypocretin neurons in the brains of human patients with Huntington's disease (HD) and in R6/2 mice have been reported. We included 10 patients with HD and 12 patients with chorea-like hyperkinetic movement disorders (non-HD). All patients of the HD group and eleven patients of the non-HD group showed normal hypocretin-1 levels. Thus, hypocretin-1 may not serve as an additional diagnostic marker for HD.

Cerebrospinal fluid from patients with dementia contains increased amounts of an unknown factor

Increased levels of an unidentified peak have been found in cerebrospinal fluid (CSF) from patients with Alzheimer's disease or vascular dementia compared to the level in healthy controls using proton magnetic resonance spectroscopy. No increase was found in patients with amyotrophic lateral sclerosis. Reexamination of spectra from a study published previously (Gårseth et al. [2000] J. Neurosci. Res. 60:779-782), however, shows that this peak was also elevated significantly in CSF from patients with Huntington's disease compared to that in controls. The level in patients with Parkinson's disease, where dementia develops in up to 40% of patients, was not elevated significantly compared to that in controls. To the best of our knowledge, this peak has not yet been identified and we therefore find it appropriate to temporarily designate the name "dementia associated factor" (DAF), although there is as yet no certainty that this substance is specific for these conditions. Apart from a significantly increased level of glutamine in CSF from patients with vascular dementia compared to that in controls, no other significant difference was found for any other metabolite measured in the patient groups using proton magnetic resonance spectroscopy.

N(epsilon)-(gamma-L-glutamyl)-L-lysine (GGEL) is increased in cerebrospinal fluid of patients with Huntington's disease

Pathological-length polyglutamine (Q(n)) expansions, such as those that occur in the huntingtin protein (htt) in Huntington's disease (HD), are excellent substrates for tissue transglutaminase in vitro, and transglutaminase activity is increased in post-mortem HD brain. However, direct evidence for the participation of tissue transglutaminase (or other transglutaminases) in HD patients in vivo is scarce. We now report that levels of N(epsilon)-(gamma-L-glutamyl)-L-lysine (GGEL)--a 'marker' isodipeptide produced by the transglutaminase reaction--are elevated in the CSF of HD patients (708 +/- 41 pmol/mL, SEM, n = 36) vs. control CSF (228 +/- 36, n = 27); p < 0.0001. These data support the hypothesis that transglutaminase activity is increased in HD brain in vivo.

Neuropeptides in CSF and post-mortem brain tissue of normal controls, schizophrenics and Huntington's choreics

Studies describing the CNS distribution of neuropeptides can provide important new insights concerning their possible physiological functions. The rational for studying human post-mortem tissue, as well as some methodological constraints, are reviewed. The localization of NT in normal human brain is presented. Concentrations of NT, TRH, and SRIF were determined in brain tissue from normal controls and patients with schizophrenia or Huntington's chorea. Specific alterations in the levels of these neuropeptides were found in each disease. Appreciable quantities of NT immunoreactivity are present in human CSF. Sub-normal CSF-NT levels were found in a sub-group of unmedicated schizophrenics but were elevated back to normal concentrations following neuroleptic treatment. Although the pathophysiological significance of these findings is unclear, they nevertheless indicate that neuropeptides are important brain constituents which deserve further study.

Proton magnetic resonance spectroscopy of cerebrospinal fluid in neurodegenerative disease: indication of glial energy impairment in Huntington chorea, but not Parkinson disease

Metabolite levels in cerebrospinal fluid from patients with Parkinson disease or Huntington chorea were compared with the levels in healthy controls using proton magnetic resonance spectroscopy. No significant differences were found for any metabolite measured in cerebrospinal fluid from patients with Parkinson disease compared to controls. Slight but significantly reduced levels of both lactate and citrate, however, were found in cerebrospinal fluid from patients with Huntington chorea compared to controls. This suggests possible impairment of both glycolysis and tricarboxylic acid cycle function. The reduction in lactate found in the present study may reflect neuronal loss. The decrease in citrate supports the theory of mitochondrial dysfunction in the brain of patients with Huntington chorea, but also suggests that there may be an important astrocytic component in this disease. If so, it would certainly have implications for neuronal function.

Safety and tolerability of the free-radical scavenger OPC-14117 in Huntington's disease. The Huntington Study Group

Oxidative damage due to free-radical generation in the setting of underlying defects of neuronal energy metabolism has been implicated as a pathogenetic mechanism for Huntington's disease (HD). The authors conducted a randomized, double-blind, placebo-controlled, multicenter trial of the tolerability of OPC-14117, a lipophilic free-radical scavenger that concentrates in the brain. Ambulatory patients with HD received OPC-14117 60 mg/d, 120 mg/d, 240 mg/d, or placebo and were assessed by the Unified Huntington's Disease Rating Scale (UHDRS) for 20 weeks, including 12 or 16 weeks of assigned treatment and 8 or 4 weeks of blinded withdrawal of the study drug. Tolerability was measured by the proportion of patients completing the initial 12-week course of treatment on their originally assigned regimen. Sixty-four patients were enrolled in the study, 56 of whom completed the 12 weeks of treatment. Treatment was discontinued in four patients (1 placebo, 1 60 mg/d, 2 240 mg/d) due to asymptomatic but persistent serum elevations of liver transaminase. Two patients (1 60 mg/d and 1 120 mg/d) withdrew because of increased involuntary movements, one patient (60 mg/d) withdrew due to persistent dry eyes, and one patient (120 mg/d) withdrew because of persistent vomiting. There were no significant differences between treatment arms in the primary measures of tolerability, the frequency and types of clinical adverse events, or the clinical/functional features of HD. OPC-14117 was safe and generally well tolerated; however, elevations of liver transaminase suggested that continued surveillance monitoring is warranted in conducting more long-term studies of this antioxidant therapy.

[Endorphins and neurotensin in Huntington chorea]

Concentration of alpha-endorphin, beta-endorphin, gamma-endorphin and neurotensin in blood and beta-endorphin in cerebrospinal fluid of 48 patients with various forms of Huntington's disease was measured. Two modifications of immunoassay were used. The level of all neuropeptides studied was significantly decreased. Patients with a kinetiko-rigid form of the disease showed a two-fold lowering in beta-endorphin levels in cerebrospinal fluid in comparison with patients with the classic form. The relationships between these findings and clinical-biochemical characteristics of Huntington's disease are discussed.

Decreased plasma alanine and isoleucine in Huntington's disease

Amino acid concentrations in plasma of patients with Huntington's disease (HD) were determined in 16 patients and 21 age- and sex-matched healthy controls. Alanine and isoleucine were significantly decreased in HD plasma whereas arginine, histidine, leucine, lysine, ornithine, proline, serine, threonine, tyrosine, and valine showed no significant changes. Our findings confirm the decreases of alanine and isoleucine that were described in plasma and cerebrospinal fluid by other investigators. A possible defect in cellular uptake or metabolism of neutral amino acids seems to be a consistent feature of HD.

Cerebrospinal fluid homovanillic acid is reduced in untreated Huntington's disease

We measured homovanillic acid (HVA), 5-hydroxy indole acetic acid (5-HIAA), and tryptophan (TP) in cerebrospinal fluid (CSF) of 20 neuroleptic-free patients with Huntington's disease (HD), and compared mean values with those from four control groups including 15 normal individuals, 38 patients with dystonia, 23 untreated patients with Parkinson's disease, and 61 patients with other neurological diseases (ONDs). The mean levels of HVA in the CSF of patients with HD were reduced compared with those from normal controls (p < 0.001), dystonic patients (p < 0.005), individuals with ONDs (p < 0.0001), and even from untreated parkinsonian patients (p < 0.05). 5-HIAA and TP levels in the CSF of patients with HD were not significantly different from those in the CSF of control patients. Our data suggest a reduced dopamine neurotransmission in HD and may account for the bradykinesia observed in our patients.

Elevated levels of the endosomal-lysosomal proteinase cathepsin D in cerebrospinal fluid in Alzheimer disease

Lysosomal hydrolases are normally intracellular enzymes but are abundant extracellularly within senile plaques in Alzheimer disease and in other conditions where beta-amyloid accumulates. To examine whether acid hydrolases released from abnormal hydrolase-laden neurons are detectable in CSF, we measured levels of the major aspartic proteinase of lysosomes, cathepsin D (Cat D), in ventricular CSF collected after death from 30 patients with Alzheimer disease, 14 patients with Huntington disease, and seven patients with other neurodegenerative diseases. The levels of Cat D-immunoreactive protein, expressed as micrograms per milliliter of protein, determined by western blot immunoassay using a polyclonal antiserum against human brain Cat D, were more than fourfold higher in the Alzheimer patients than in the other patient groups (p < 0.0005). Cat D activity, assayed separately against [14C]methemoglobin at pH 3.2, was also significantly elevated but less than Cat D content. The lower specific activity of Cat D in Alzheimer CSF therefore indicated that the abnormally accumulated Cat D included a high proportion of inactive enzyme. These results indicate that abnormal Cat D release from affected neurons into the extracellular space is an active, ongoing process in Alzheimer brain. In addition, the levels of this enzyme and possibly other lysosomal hydrolases in CSF may prove to be useful biological markers of Alzheimer disease.

Cerebrospinal fluid nitrite/nitrate levels in neurologic diseases

Nitric oxide has been proposed to mediate cytotoxic effects in inflammatory diseases. To investigate the possibility that overproduction of nitric oxide might play a role in the neuropathology of inflammatory and noninflammatory neurological diseases, we compared levels of the markers of nitric oxide, nitrite plus nitrate, in the CSF of controls with those in patients with various neurologic diseases, including Huntington's and Alzheimer's disease, amyotrophic lateral sclerosis, and HIV infection. We found that there were no significant increases in the CSF levels of these nitric oxide metabolites, even in patients infected with HIV or in monkeys infected with poliovirus, both of which have significantly elevated levels of the neurotoxin quinolinic acid and the marker of macrophage activation, neopterin. However, CSF quinolinic acid, neopterin, and nitrite/nitrate levels were significantly increased in a small group of patients with bacterial and viral meningitis.

Analysis of glial fibrillary acidic protein in the cerebrospinal fluid of children investigated for encephalopathy

The clinical application of a newly developed highly sensitive ELISA method (20) to assay glial fibrillary acidic protein (GFAP) in the cerebrospinal fluid (CSF) was investigated in children and adolescents with neurological disorders. GFAP analysis was explored as a tool to differentiate disorders with ongoing astrocytosis. A consecutive series of 34 subjects, 17 boys and 17 girls, with nonprogressive and progressive neurological encephalopathies was compared to 10 healthy controls. The mean CSF GFAP concentration of the controls was 60.6 +/- 54 ng/l (SD). The group of 24 subjects (12 boys and 12 girls) with progressive neurologic disorders had higher mean CSF GFAP levels than the group of 10 subjects (5 boys and 5 girls) with non-progressive disorders, 222.6 +/- 186 and 127.5 +/- 86 ng/l, respectively. The progressive encephalopathies differed significantly from controls (p < 0.01) while the non-progressive did not. The mean GFAP concentration of the epilepsy cases (n = 18) and non-epilepsy cases (n = 16) was 212.9 +/- 196 and 174.0 +/- 132 ng/l, respectively. The epilepsy cases differed significantly from controls which could be explained by the dominance of progressive cases (15 out of 18).(ABSTRACT TRUNCATED AT 250 WORDS)

CSF and serum metabolic profile of patients with Huntington's chorea: a study by high resolution proton NMR spectroscopy and HPLC

We studied both cerebrospinal fluid (CSF) and serum of 11 patients suffering from Huntington's disease (HD) and 12 control subjects by combining high resolution proton NMR spectroscopy and HPLC. NMR spectroscopy analysis of the CSF shows a significant increase (60%) in pyruvate concentration in HD patients. No unexpected molecules were detected. Glutamate, glutamine, aspartate, proline and GABA levels were found unchanged in the CSF of HD patients, using HPLC analysis. Conversely, a significant increase (30%) in the CSF level of glycine was detected. These observations are in agreement with the metabolic hypothesis of HD physiopathogenesis. In addition, the protocol combining NMR spectroscopy and HPLC provides a straightforward evaluation of brain metabolic status and blood-brain-barrier function.

Reduced regional cerebral blood flow in Huntington's disease studied by SPECT

Regional cerebral blood flow (rCBF) was studied in 18 patients with Huntington's disease (HD) and 19 age- and sex-matched controls with high resolution single photon emission computerised tomography (SPECT), using Tc-99m-HMPAO. Significant reductions in tracer uptake were found in the caudate and lentiform nuclei (20 and 8%) and in the cerebral cortex, especially in the frontal and parietal areas (11-13%). No significant reductions were found in the thalamus, mesial temporal cortex, and occipital cortex. Fourteen patients had neuropsychological testing. Relationship between rCBF and cognitive function was tested by regression analysis. A linear relationship was found between test scores of Wisconsin Card Sorting Test, Picture Arrangement Test and blood flow in the caudate nucleus. Other tests of cognitive function (Block Design Test, Face and Word Recognition Test, Street Fragmented Pictures Test, and Similarities Test) correlated better with flow in the cortical regions believed to be involved in solving those particular tests. These findings indicate, that blood flow is reduced in both cortical and subcortical structures in symptomatic HD, and that both reductions in cortical and subcortical blood flow may be related to cognitive function in HD.

Putamen volume reduction on magnetic resonance imaging exceeds caudate changes in mild Huntington's disease

The characteristic pathological features of Huntington's disease (HD) are neostriatal atrophy and neuronal loss. Although neuroradiological studies often show caudate atrophy in patients with moderate HD, frequently no caudate atrophy is found early in the illness. There have been no quantitative reports to date on in vivo putamen volume measures in mild HD, although the structure is known to be neuropathologically involved in the illness. We measured volumes of caudate nucleus and putamen and bicaudate ratios (BCR) from magnetic resonance images, blind to diagnosis, in 15 patients with mild HD and 19 age- and sex-matched control subjects using a computerized image analysis system. The region showing greatest atrophy was the putamen, which was reduced 50.1% in mean volume in HD patients compared with control subjects (p less than 0.000001). In contrast, caudate volume was reduced 27.7% (p = 0.004). BCR was increased 28.5% in HD patients (p = 0.0002). Discriminant function analysis was 94% effective in identifying the diagnostic group based on putamen volume alone, whereas caudate measures had considerable overlap. Correction of putamen volume for head size led to 100% separation by group. Putamen measures and BCR correlated with neurological examination scores but caudate volume did not. Volumetric measurement of putamen is a more sensitive indicator of brain abnormalities in mild HD than measures of caudate atrophy.

Increased cerebrospinal fluid dopamine and 3,4-dihydroxyphenylacetic acid levels in Huntington's disease: evidence for an overactive dopaminergic brain transmission

Levels of dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), noradrenaline (NA), 3-methoxy-4-hydroxyphenylglycol (MHPG), and 5-hydroxyindoleacetic acid (5-HIAA) in the CSF of patients with Huntington's disease (HD) were measured by HPLC. CSF DA, DOPAC, and MHPG levels were found to be increased in HD patients. Levels of HVA, 5-HIAA, and NA in the CSF of HD patients did not differ from those of controls. Changes in CSF DA and DOPAC levels were consistent with previous findings of increased DA tissue content in some brain areas of patients with HD. These results suggest that CSF DOPAC levels could be a more reliable index of overactive dopaminergic brain systems in HD than CSF HVA levels.

Regional brain and cerebrospinal fluid quinolinic acid concentrations in Huntington's disease

Many of the characteristics neuroanatomical and neurochemical features of Huntington's disease (HD) are produced in experimental animals by an intrastriatal injection of the endogenous N-methyl-D-aspartate receptor agonist quinolinic acid (QUIN). Conceivably, a chronic over-production of QUIN in brain could be involved in the pathogenesis of HD. To investigate this hypothesis, concentrations of QUIN were measured both in cerebrospinal fluid (CSF) and postmortem tissue from patients with HD and neurologically normal age-matched controls. CSF QUIN concentrations were slightly lower in patients with HD, however the changes were not significant. Mean concentrations of QUIN tended to be lower in HD putamen, dentate nucleus and several cortical regions, although significant reductions were found only in Brodmann areas 17, 20 and 28. The mechanisms responsible for these small reductions in brain QUIN concentrations remain to be determined. These results do not support the hypothesis that a chronic increase of QUIN production is responsible for neurodengeneration in HD.

Histamine metabolites and pros-methylimidazoleacetic acid in human cerebrospinal fluid

In cerebrospinal fluid, levels of the histamine metabolites, tele-methylhistamine and tele-methylimidazole-acetic acid, were higher in elderly than in young people, and women had higher levels than men. Therefore, age and gender should be considered in studies of histamine metabolites as exemplified by their measurements in cerebrospinal fluid of patients with Huntington's disease. Levels of pros-methylimidazoleacetic acid, an isomer of tele-methylimidazoleacetic acid and not a metabolite of histamine, were higher in cerebrospinal fluid of men than of women. Levels of pros-methylimidazoleacetic acid in cerebrospinal fluid were highly positively correlated with the severity of Parkinson's disease in a group of non-medicated, mildly to moderately affected patients.

Cerebrospinal fluid acetylcholinesterase and choline measurements in Huntington's disease

The caudate nucleus has the highest acetylcholinesterase (AChE) activity in the brain and it has been shown that autopsied brain tissue of patients with Huntington's disease (HD) have reduced levels of acetylcholine. Because of these findings, the cholinergic function in HD was studied by measuring cerebrospinal fluid (CSF) choline levels and AChE activity during a randomized, double-blind, cross-over, placebo-controlled clinical trial of isoniazid. While mean choline levels adjusted for age were lower compared with controls (P = 0.0007), AChE activity did not differ between HD patients and normal controls. Treatment with isoniazid had no significant effect on CSF choline levels or CSF AChE activity. CSF AChE activity showed a statistically significant increase with advancing age. The reduced level of choline in CSF of HD patients may reflect either a defect in choline transport into the brain or a decrease of choline-phospholipid output from the brain.

Cerebrospinal fluid levels of diazepam-binding inhibitor in neurodegenerative disorders with dementia

We investigated CSF levels of diazepam-binding inhibitor (DBI), a recently discovered neuropeptide that allosterically modulates GABAergic transmission, in various neurodegenerative disorders with dementia (28 patients with Parkinson's disease, 10 with Alzheimer's disease, 7 with Huntington's chorea). We applied a battery of neuropsychological tests to determine the degree of dementia and to exclude the presence of mood alterations. CSF DBI levels were elevated in parkinsonian subjects with dementia and in patients with Alzheimer's disease, but decreased in Huntington's chorea patients. We hypothesize that modifications of CSF DBI levels may be related to a functional or structural alteration of the GABAergic system.

What excitotoxin kills striatal neurons in Huntington's disease? Clues from neurochemical studies

Amino acid analyses of both caudate nucleus and putamen obtained at autopsy from patients dying with Huntington's disease (HD), and from control subjects, showed significantly decreased mean glutamate contents in the HD patients. In addition, the mean glutamate concentration was significantly increased in the CSF of living HD patients as compared with controls. Neurochemical studies also showed that neither aspartic acid, proline, 5-oxoproline, nor homocysteic acid is likely to act as a causative excitotoxin in HD. Excessive striatal glycine content, or deficient glutathione content, is unlikely to contribute to the effects of a causative excitotoxin in HD. We suggest that glutamic acid may be the proximate causative neurotoxin in the striatum in HD, as a result of an unexplained failure in the reuptake mechanism for glutamate released there as an excitatory neurotransmitter.

Decrease in a proenkephalin peptide in cerebrospinal fluid in Huntington's disease and progressive supranuclear palsy

The cerebrospinal fluid (CSF) content of Met5-enkephalin-Arg-Gly-Leu immunoreactivity was found to be significantly decreased in patients with Huntington's disease and progressive supranuclear palsy. This peptide is derived from the proenkephalin precursor protein and normally is found in high concentrations in the basal ganglia. The decrease in CSF from Huntington's disease patients likely reflects the loss of proenkephalin-containing neurons seen in postmortem analyses of basal ganglia tissue. The decrease in progressive supranuclear palsy, a disease in which dopamine neurons degenerate but enkephalin levels in the basal ganglia are reportedly not decreased, may reflect a functional decline in enkephalinergic neuronal activity secondary to a striatal cholinergic deficit. The results suggest that a substantial portion of the CSF Met5-enkephalin-Arg-Gly-Leu immunoreactivity is derived from the basal ganglia and that CSF levels of this peptide can serve as an index of functional or anatomical integrity of proenkephalin synthesizing neurons in the basal ganglia.

Isoniazid-induced alteration of CSF neurotransmitter amino acids in Huntington's disease

During a randomized, double-blind, crossover, placebo-controlled clinical trial of isoniazid (plus pyridoxine) in Huntington's disease (HD), amino acids and related amino compounds were measured in both cerebrospinal fluid (CSF) and plasma utilizing a newly developed high-performance liquid chromatography ion-exchange/fluorometric assay method. Results showed that isoniazid (plus pyridoxine) significantly elevated the mean (+/- S.E.M.) levels of gamma-aminobutyric acid, aspartate, asparagine, homocarnosine, ornithine, histidine, alpha-aminobutyric acid, isoleucine, leucine and alanine in CSF and the levels of beta-alanine in both CSF and plasma. These alterations can be traced to inhibition of decarboxylation and transamination reactions requiring the cofactor pyridoxal phosphate and may be related to the observed equivocal clinical response in the HD patients. The differential influence of isoniazid on plasma and CSF amino acid profiles suggests that alterations of CNS amino acid metabolism may be reflected in CSF, and that isoniazid-induced alterations of amino acid metabolism in the CNS differ from those in the periphery.

Free and conjugated CSF and plasma GABA in Huntington's chorea

Free and conjugated GABA concentrations were measured in CSF and plasma from 28 patients with manifest Huntington's chorea (HC) and 30 age- and sex-matched controls. GABA was determined by ion-exchange chromatography with fluorimetric detection (IE/F). Free and conjugated CSF GABA was significantly decreased in prolonged HC with advanced disease states and was suggested practicable as an additional diagnostic tool. However, in younger patients (less than 40 yrs) with a short period of HC (less than 2 yrs) an overlap with the age-matched normal range indicated GABA measurement inadequate to early diagnosis nor predictive for offspring at risk. An age-dependent decrease of conjugated CSF GABA was observed in patients and controls. The more pronounced decrease in patients might reflect the neurodegenerative feature of HC.

CSF somatostatin-like immunoreactivity in dementia

Concentrations of somatostatin-like immunoreactivity (SLI) in CSF were reduced in Alzheimer's disease (AD) and multi-infarct dementia (p less than 0.01), but not in normal-pressure hydrocephalus, Parkinson's disease, and Huntington's disease. This suggests that reduced SLI content in AD cerebral cortex is reflected in CSF. Chromatographic characterization of CSF SLI showed no differences between AD and controls. Concentrations of SLI in AD patients overlapped those in both normal subjects and patients with multi-infarct dementia, so that changes in CSF SLI have no diagnostic specificity.

Neurochemistry of dopamine in Huntington's dementia and normal aging

We measured the dopamine metabolite homovanillic acid (HVA) in cerebrospinal fluid (CSF) before and after probenecid administration in normal controls and in patients with Huntington's disease. Baseline CSF HVA concentrations correlated positively with age in normal control subjects. Baseline CSF HVA concentrations were reduced in patients with Huntington's disease, and the degree of this reduction correlated with the severity of dementia and with the duration of disease. These results suggest that changes in the metabolism of dopamine by dopaminergic neurons may be associated with the dementia of Huntington's disease as well as with normal aging. These changes in dopaminergic functioning are apparently different in Huntington's disease than in normal aging and can be detected by measuring CSF HVA concentration.

Free and conjugated GABA in human cerebrospinal fluid: effect of degenerative neurologic diseases and isoniazid

gamma-Aminobutyric acid (GABA) was measured in CSF as such and following acid hydrolysis by the ion-exchange/fluorometric method. The conjugated GABA level was obtained by subtracting the free GABA level from the total GABA level. Results showed that at room temperature, while the free GABA level increased, the level of conjugated GABA decreased in a linear fashion during the first 24 h (r = -0.974; P less than 0.001). Aging and CSF conjugated GABA levels were inversely correlated (r = -0.613; P less than 0.05). Unlike free GABA levels, the levels of conjugated GABA were not altered in Huntington's disease, Parkinson's disease, cerebellar ataxias, dementias, epilepsy and multiple sclerosis compared to controls. In patients with Huntington's disease, on administration of isoniazid at 900 mg/day, along with pyridoxine at 100 mg/day, a 4-fold increase of both free (P less than 0.005) and conjugated GABA (P less than 0.0025) was seen. The results indicate that while total GABAergic peptides are not altered in several of the neurologic diseases studied, drugs such as isoniazid and/or pyridoxine can significantly elevate both free and conjugated GABA levels in human CSF.

Further characterization of in vitro conditions appropriate for GABA determination in human CSF: impact of acid deproteinization and freeze/thaw

Recently established standardized protocols for collection, handling, and storage of CSF for measurement of gamma-aminobutyric acid (GABA) have proven valuable in the characterization of various CNS disorders. In response to two recent reports which may have an impact on certain widely used protocols, we have, using the confirmed ion-exchange/fluorometric procedure, systematically evaluated the effects of deproteinization with various concentrations of sulfosalicylic acid (SSA) ranging from 0 to 10% (100 mg/ml), as well as the effects of freeze/thaw (F/T) on CSF GABA levels. Results of F/T studies documented that levels are stable to freezing and thawing. Acid deproteinization studies revealed the presence of an equilibrium between strictly free GABA, demonstrable only in acid-free CSF, and a very loosely bound form of GABA, fully demonstrable only in CSF deproteinized with concentrations of SSA above 1% (10 mg/ml). The relationship between GABA concentrations in undeproteinized and acid-deproteinized CSF revealed a highly significant (p less than .001) correlation, suggesting that alterations of central GABAergic activity would be reflected by either the level of strictly free GABA or free plus loosely bound GABA. This hypothesis was upheld in studies of patients with Parkinson's disease (PD) and Huntington's disease (HD), two neurologic disorders in which dysfunctions of the GABA system have been implicated. Results indicated that CSF GABA levels are significantly reduced in both PD and HD patients compared with neurologically normal controls, whether the measurement is of free GABA or free plus loosely bound GABA. Thus, we conclude that the level of strictly free GABA is stable to freezing and thawing and can only be accurately determined in nonacidified CSF; however, existing protocols employing deproteinization in 5% SSA yield data that provide an equally good reflection of central GABAergic transmission.

Decreased level of beta-endorphin-like immunoreactivity in cerebrospinal fluid of patients with senile dementia of Alzheimer type

beta-Endorphin-like immunoreactivity in cerebrospinal fluid(CSF) was observed to decrease in patients with Huntington's disease and dementia due to brain vascular disease. The greatest decrease was seen in patients with presenile and senile dementia of Alzheimer type(SDAT). The immunoreactivity significantly correlated with psychological functions when examined using a dementia rating scale (r=0.51, p less than 0.01, for all dementia, r=0.65, p less than 0.02, for only SDAT). These results suggest that a B-endorphin-like substance may be related in the pathophysiology of dementia.

Further studies of the cytopathic effect in tissue cultures inoculated with CSF from patients with schizophrenia and other nervous system diseases

Tissue cultures were inoculated with CSF from patients with schizophrenia and some other psychiatric and neurological illnesses. The CPE was readily seen in all 13 strains of human skin fibroblasts examined but could not be serially passaged. The results of retesting many specimens, either by the same worker or under full double blind conditions, usually agreed and thus indicate that the CPE was due to the CSF and not to non specific changes in the cultures. CPE was seen in cultures in which mycoplasmas could not be detected. Degenerated cultures show polymorphous nuclei with condensed nuclear chromatin and enlarged mitochondria with few cristae but virus particles were not identified. The physical properties of the agent in the CSF that induced the CPE were the same as those reported earlier for CSF from schizophrenic patients.

An investigation of the effects of intracerebral injection in the marmoset of cytopathic cerebrospinal fluid from patients with schizophrenia or neurological disease

In experiments designed to investigate transmission, cerebrospinal fluid (CSF) from patients with schizophrenia and neurological disease (huntington's chorea and multiple sclerosis) which had been found to induce cytopathic effects in human embryonic fibroblast cell culture was injected intracerebrally into mice, hamsters and marmosets (small New World primates). No evidence was obtained of transmission to mice or hamsters. A total of 15 marmosets (Callithrix jacchus) was injected intracerebrally with CSF [8 with samples from 4 patients with schizophrenia. 3 with samples from patients with neurological disease (2 with Huntington's chorea and 1 with multiple sclerosis) and 4 with samples from 3 patients without neurological or psychiatric disease] and was observed over a period of 2 1/2 years. Analysis of variance on data obtained from behavioral observations averaged over 6-month periods revealed that animals injected with CSF from patients with schizophrenia and neurological disease became progressively more inactive when compared with animals injected with CSF from control patients. The change detected by behavioural observation was confirmed as a difference 2 and 2 1/2 years after injection by automated activity monitoring. There was an incidence of reproductive anomalies (including two occipital encephalocoeles) in the females in the experimental group, but the numbers are too small to draw firm conclusions from this observation. Many reported differences in biological samples from schizophrenic patients and normal controls have subsequently been found to be due to factors unrelated to the disease state. This may prove to be the case with the changes observed in this experiment. Nevertheless, the fact that marmosets injected with CSF from patients suffering from neuropsychiatric disease, including schizophrenia, subsequently differed in their behaviour from those injected with control CSF warrants further investigation.