Low HVA and normal 5HIAA CSF levels in drug-free schizophrenic patients compared to healthy volunteers: correlations to symptomatology and family history

Plasma homovanillic acid, plasma anti-D1 and -D2 dopamine-receptor activity, and negative symptoms in chronically mediated schizophrenia

We have investigated the relationship between the concentration of homovanillic acid in human plasma (pHVA) and plasma anti-D1 and anti-D2 dopamine receptor activity in chronic schizophrenic patients whose neuroleptic dosage was changed. The change in pHVA level correlated with that in anti-D1, not anti-D2 activity, thus suggesting that the neuroleptic-induced changes in pHVA concentration may be associated with the blocking of D1- as well as D2- receptors. The change of scores on the Scale for the Assessment of Negative Symptoms did not significantly correlate with changes in anti-D1 or anti-D2 activity, but did so correlated with the change in pHVA level.

Schizophrenia and the D1 receptor: focus on negative symptoms

Negative symptoms have been associated with structural impairment in the PFC, and hypothesized to arise from a central hypodopaminergic substrate. Corticofugal PFC neurons, which are inhibited by VTA DA innervation, exert a tonic excitatory modulation on DA activity in the NAS. Lesions of ascending DA forebrain projections "uncouple" the functional link between D1 and D2 receptors, permitting independent activation of D1 sites in generating behavioral output. A previously identified absence of this D1/D2 link in schizophrenic brain suggests that functional activation of PFC D1 receptors may induce hyperinhibition of descending corticofugal efferents to the NAS. Consequent hypoactivity of DA in the NAS is proposed to give rise to negative symptoms of schizophrenia, and low dose DA agonist treatments may mimic behavioral features of this symptom profile via direct PFC D1 stimulation. It follows that clozapine's efficacy for negative symptoms may be attributable, in part, to blockade of PFC D1 receptors, with subsequent enhancement of glutamate-facilitated NAS DA activity.

Regional brain glucose metabolism: correlations to biochemical measures and anxiety in patients with schizophrenia

Regional brain glucose metabolism in 20 patients with schizophrenia (DSM-III) was investigated by positron emission tomography (PET) with uniformly labeled 11C-glucose as the tracer. Monoamine metabolites were analyzed in cerebrospinal fluid (CSF) and serum, and prolactin was analyzed in serum. Intensity of anxiety was rated directly after the PET study. Ten healthy volunteers served as controls. In the patients, weak positive and negative relationships were found between homovanillic acid in CSF and prolactin in serum, respectively, and regional metabolic rates. In all subjects, positive correlations were found between the level of anxiety and the regional glucose metabolism. In the controls, positive correlations were found between anxiety and the frontal/parietal ratios of the left hemisphere, whereas anxiety scores of the patients correlated negatively to relative metabolic rates of the right medial frontal cortex and the left thalamus. These observations may indicate alterations in the neuronal systems participating in the initiation of anxiety and arousal in schizophrenia.

Limbic/mesolimbic connections and the pathogenesis of schizophrenia

The development of models of the pathogenesis of neuropsychiatric diseases that build on recent advances in chemical neuroanatomy will help to guide future research. The interconnections among limbic, basal ganglia, and cortical structures are used to form the basis of a hypothesis of the pathogenesis of schizophrenia. The adaptive capacity of subcortical dopamine systems is advanced as an explanation of the many states of the disease.

Dopamine and norepinephrine activity in schizophrenia. An integrative perspective

The dopamine (DA) hypothesis of schizophrenia stated that increased DA activity is the primary cause of schizophrenia. Recently, even though increased DA activity is in fact involved in psychotic symptoms and antipsychotic drug response, it has become clear that decreased DA activity is present in remitted and chronic states and may relate to deficit symptoms and cortical lesions. In addition, the norepinephrine (NE) system seems to be involved in symptomatology, antipsychotic drug response, course, and outcome in schizophrenia. This review supports the hypothesis that a disturbance in DA and NE activity regulates schizophrenic behavior. A plethora of DA- and NE-related findings in schizophrenic patients are reviewed in relationship to each other according to basic science data and to presently entertained hypotheses, with emphasis on a neural developmental disturbance interacting with a genetic predisposition shaped by environmental factors.

Commentary on the Modified Rogers Scale and the 'conflict of paradigms' hypothesis

The variety and complexity of schizophrenic movement disorders renders them difficult to assess. In particular, the complex disorders of motility that appear to reflect disturbance of the will demand an evaluation of the purpose of the movement. The difficulties of assessment are compounded by the fact that the antipsychotic drugs used to treat the illness can produce motor disorders that resemble the disorders intrinsic to the illness. In advancing his ‘conflict of paradigms' hypothesis, Rogers (1985) implied that emphasis on the distinction between intrinsic and drug-induced movement disorders might be misplaced because of overlap not only in the observable characteristics of these disorders, but also in the underlying neuropathology.

Phasic versus tonic dopamine release and the modulation of dopamine system responsivity: a hypothesis for the etiology of schizophrenia

A novel mechanism for regulating dopamine activity in subcortical sites and its possible relevance to schizophrenia is proposed. This hypothesis is based on the regulation of dopamine release into subcortical regions occurring via two independent mechanisms: (1) transient or phasic dopamine release caused by dopamine neuron firing, and (2) sustained, "background" tonic dopamine release regulated by prefrontal cortical afferents. Behaviorally relevant stimuli are proposed to cause short-term activation of dopamine cell firing to trigger the phasic component of dopamine release. In contrast, tonic dopamine release is proposed to regulate the intensity of the phasic dopamine response through its effect on extracellular dopamine levels. In this way, tonic dopamine release would set the background level of dopamine receptor stimulation (both autoreceptor and postsynaptic) and, through homeostatic mechanisms, the responsivity of the system to dopamine in these sites. In schizophrenics, a prolonged decrease in prefrontal cortical activity is proposed to reduce tonic dopamine release. Over time, this would elicit homeostatic compensations that would increase overall dopamine responsivity and thereby cause subsequent phasic dopamine release to elicit abnormally large responses.

Monoamines and abnormal behaviour. A multi-aminergic perspective

Classical nosology has been the cornerstone of biological psychiatric research; finding biological markers and eventually causes of disease entities has been the major goal. Another approach, designated as 'functional', is advanced here, attempting to correlate biological variables with psychological dysfunctions, the latter being considered to be the basic units of classification in psychopathology. Signs of diminished DA, 5-HT and NA metabolism, as have been found in psychiatric disorders, are not disorder-specific, but rather are related to psychopathological dimensions (hypoactivity/inertia, increased aggression/anxiety, and anhedonia) independent of the nosological framework in which these dysfunctions occur. Implications of the functional approach for psychiatry include a shift from nosological to functional application of psychotropic drugs. Functional psychopharmacology will be dysfunction-orientated and therefore geared towards utilising drug combinations. This prospect is hailed as progress, both practically and scientifically.

The relationship of negative schizophrenia to parkinsonism

The positive-negative distinction of schizophrenia has emerged as a valid means of clarifying its heterogeneity. Despite evidence that the two symptom classes may reflect different dimensions of the disease, there is presently no integrated model for understanding of the pathophysiology of these symptoms and their co-occurrence in schizophrenia. We propose that negative phenomena of schizophrenia may be a variant of Parkinsonism. This view is supported by the overlap with Parkinsonism in terms of clinical features, neurochemistry, pharmacology, as well as neuroradiological and neuropathological aspects. As such, negative symptoms may be a manifestation of disease of the basal ganglia and constitute the core pathology in schizophrenia. Positive symptoms, conversely, may reflect an "accessory" process related to a compensatory increase in striatal and limbic dopamine activity following an injury to the dopaminergic system. In the present communication we present a series of studies that support the association of negative schizophrenia and Parkinsonism. Based on this evidence, we suggest that schizophrenic patients with prominent negative symptoms might be managed like patients with Parkinson's disease, namely, with dopaminergic drugs and MAO-B inhibitors. Finally, the association of negative schizophrenia with Parkinsonism raises the possibility that adrenal medullary tissue transplantation, which may benefit a selected group of Parkinsonian patients, may be a future promising therapy for refractory negative schizophrenia.

Two-tier diagnosing in psychiatry

This article addresses the question: what is the most productive way to systematize abnormal behavior in order to study its biological roots? Though nosology still occupies the premier position in biological psychiatry, it is, in and by itself, a treacherous beacon. Syndromal organization of psychopathology is likewise seriously flawed. A functional organization of psychopathology is considered the most appropriate framework for biological research and a plea is made for a two-tier diagnostic system of psychiatric disorders. Tier one comprises the nosological diagnosis, and tier two a detailed depiction of the component psychological dysfunctions. Such a two-tier diagnostic system would bring psychopathology onto a true scientific footing.

Relationship between abnormal brainstem auditory-evoked potentials and subnormal CSF levels of HVA and 5-HIAA in first-episode schizophrenic patients

Auditory brainstem-evoked responses (ABRs) were recorded and the CSF concentration of the amine metabolites homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) were measured in 39 drug-free schizophrenic patients. Twenty-four of the patients were first admissions and had never received antipsychotic medication. The ABRs were judged according to our normative data and the CSF concentrations of the amine metabolites were compared with those of 47 healthy volunteers. Clear-cut abnormal ABRs, identified as a lack of one or more peaks or abnormal peak latencies, were found in 15 patients. In controls and patients with normal ABRs, there was a significant positive correlation between the cerebrospinal fluid (CSF) levels of HVA and 5-HIAA; no such correlation was found in patients with abnormal ABRs. Schizophrenics with abnormal ABRs had significantly lower levels of HVA, but not 5-HIAA, in the CSF when compared with controls. Schizophrenic patients with normal ABRs (n = 24) did not differ from the controls with regard to the amine metabolites in CSF. A comparison of the CSF levels of HVA and 5-HIAA yielded no significant difference between patients with normal and those with abnormal ABRs. In contrast, when only first-episode, never-treated schizophrenics were considered, patients with abnormal ABRs (n = 10) had significantly lower levels of both HVA and 5-HIAA when compared with those having normal ABRs (n = 14). The results indicate an association between brainstem dysfunction and reduced central nervous dopaminergic and possibly also serotoninergic activity in schizophrenia.

5-HIAA in cerebrospinal fluid and deficit schizophrenic characteristics

Higher CSF 5-HIAA concentrations and lower CSF HVA concentrations have been associated with various measures of slowed motor behaviour and communication in schizophrenic patients. To derive a single, reliable measure of deficit characteristics in schizophrenic patients, we entered four items of the BPRS reflecting negative symptoms, a work history measure derived from the Strauss-Carpenter scale, and three subscale scores of the WAIS-R into a principal-components analysis to derive a single factor score. The CSF 5-HIAA concentrations were within the normal range of values, and correlated directly with this factor score, but CSF HVA concentrations were not associated with the deficit factor score. These findings add support to the hypothesis that brain serotonin function is associated with deficit schizophrenic characteristics.

Double blind comparative study of remoxipride and haloperidol in acute schizophrenic patients

In the present 6-week double-blind, randomised, multicentre study, the atypical neuroleptic remoxipride was compared to haloperidol in acute schizophrenic patients (DSM-III). Seventy-one patients entered the study, 36 in the remoxipride group and 35 in the haloperidol group. There were ten early withdrawals, four in the remoxipride group and six patients in the haloperidol group. The Present State Examination (PSE) profile revealed a similar reduction in the symptom clusters of psychosis in both treatment groups. Forty-seven per cent of the patients in the remoxipride group and 34% of the patients in the haloperidol group showed clinically relevant improvement (reduction of BPRS total score greater than or equal to 50%). All extrapyramidal symptoms except "glabella tap" occurred significantly less frequently in the remoxipride group as compared to the haloperidol group. Substantially lower incidences of EPS were found by active questioning in the remoxipride group compared to the haloperidol group. In addition, considerably lower incidences were observed in the remoxipride group with respect to drowsiness/somnolence, tiredness/fatigue and concentrating difficulty. At the end of treatment 66% of the patients in the haloperidol group and 22% in the remoxipride group were using anticholinergics. No consistent changes were found in the mean plasma HVA level in either treatment group. In responders (reduction of BPRS total score greater than or equal to 50%) lower baseline HVA levels were observed in both treatment groups. This study indicates that the newly developed neuroleptic remoxipride is an effective antipsychotic compound, which is clinically safe and well tolerated. In particular, few EPS were induced by remoxipride, as compared to haloperidol.

A mechanism for the involvement of colocalized neuropeptides in the actions of antipsychotic drugs

Evidence has accumulated to implicate neuropeptides localized within midbrain dopamine neurons (cholecystokinin, neurotensin, acetylcholinesterase) in synaptic transmission, mental disease, and pharmacotherapy. We suggest a means by which antipsychotic drugs alter the dynamics between dopamine and colocalized peptides: the intrinsic ability of these agents to stimulate dopamine neuronal activity while blocking dopamine receptors modulates the ratio of catecholaminergic to peptidergic transmission within the mesotelencephalic system. Imbalances of peptide and dopamine cotransmission and their modulation by neuroleptics may be relevant to the pathogenesis and pharmacotherapy of schizophrenia.

Biogenic amines and their metabolites in body fluids of normal, psychiatric and neurological subjects

The biogenic monoamines and their metabolites have been isolated, identified and quantified in human body fluids over the past forty years using a wide variety of chromatographic separation and detection techniques. This review summarizes the results of those studies on normal, psychiatric and neurological subjects. Tables of normal values and the methods used to obtain them should prove to be useful as a reference source for benchmark amine and metabolite concentrations and for successful analytical procedures for their chromatographic separation, detection and quantification. Summaries of the often contradictory results of the application of these methods to psychiatric and neurological problems are presented and may assist in the assessment of the validity of the results of experiments in this field. Finally, the individual, environmental and the methodological factors affecting the concentrations of the amines and their metabolites are discussed.

Plasma and CSF HVA before and after pharmacological treatment

Plasma and cerebrospinal fluid (CSF) levels of the major dopamine metabolite homovanillic acid (HVA) were measured in psychiatric patients after an average washout period of 19 days, and again after 4 weeks of pharmacological treatment. Absolute values of plasma HVA did not correlate with absolute values of CSF HVA either at baseline or after treatment. However, changes in plasma HVA were highly correlated with changes in CSF HVA. Further, while baseline levels of plasma and CSF HVA were not significantly correlated with baseline clinical measures, clinical improvement was associated with decreases in both plasma and CSF HVA. This reached statistical significance for the plasma HVA level/clinical response relationship.

The positive/negative symptom distinction in schizophrenia. Validity and etiological relevance

This paper presents an overview of the literature on the positive/negative symptom distinction in schizophrenia, and explores the implications of the findings for etiological models. Despite the diversity in methodology and focus, certain consistencies emerge from the research. Most important are findings that negative symptoms show a stronger relation with premorbid dysfunction than positive symptoms, and are more predictive of concordance for schizophrenia in monozygotic twins. Thus it appears that negative symptom ratings partially tap some long-standing characteristics of the individual. Moreover, these characteristics appear to be influenced by genetic factors. The implications of the findings for models of the etiology of positive and negative symptoms are discussed.

Decreased tyrosine transport in fibroblasts from schizophrenic patients

Amino acid transport was studied in vitro in cultured fibroblasts from schizophrenic patients and controls. An isolated decrease in the transport capacity (Vmax) for tyrosine was observed in cells from the patients. The Km for tyrosine transport was unaffected. The kinetic parameters for phenylalanine, tryptophan, leucine and glycine transport did not differ between patients and controls. Competitive inhibition among the amino acids transported by the L-system and its exchange properties were normal in cells from the patients. No differences in intracellular levels of amino acids between patients and controls were observed. The decreased tyrosine transport in the cells from schizophrenic patients appears not to be related to any known amino acid transport system and may reflect a more general defect in plasma membrane function in schizophrenia.