The membrane phospholipid hypothesis as a biochemical basis for the neurodevelopmental concept of schizophrenia

Increased calcium-independent phospholipase A2 activity in first but not in multiepisode chronic schizophrenia

BACKGROUND

Increased activity of calcium independent phospholipase A2 (iPLA2) has repeatedly been found in the serum of unmedicated first-episode schizophrenia patients and assumed to reflect a pertubation of phospholipid metabolism. Previous studies in chronic schizophrenia were less conclusive. To explore whether iPLA2 changes are stage dependent, we investigated serum iPLA2 activity in various stages of schizophrenia.

METHODS

iPLA2 activity was assessed in the serum of 30 first-episode and 23 multiepisode schizophrenia patients and 53 healthy control subjects matched for age and gender. A fluorimetric assay was applied using the PLA2 specific substrate NBDC6-HPC, thin-layer chromatography of reaction products, and digital image scanning for signal detection.

RESULTS

Group comparison between first-episode and multiepisode patients and corresponding control groups revealed significantly increased iPLA2 activity only in first-episode patients. Enzyme activity in first-episode patients was also markedly increased, compared with chronic patients. iPLA2 changes observed were irrespective of neuroleptic medication, age, or gender.

CONCLUSIONS

Our results suggest increased lipid turnover in the acute early phase of schizophrenia that is less obvious in chronic stages. Future longitudinal studies involving iPLA2 activity and phosphorous magnetic resonance spectroscopy need to address the relation between perturbed brain lipid metabolism and iPLA2 increment in the course of schizophrenia.

Cerebrospinal anandamide levels are elevated in acute schizophrenia and are inversely correlated with psychotic symptoms

The endocannabinoids are a family of bioactive lipids that activate CB1 cannabinoid receptors in the brain and exert intense emotional and cognitive effects. Here, we have examined the role of endocannabinoid signaling in psychotic states by measuring levels of the endocannabinoid anandamide in cerebrospinal fluid (CSF) of acute paranoid-type schizophrenic patients. We found that CSF anandamide levels are eight-fold higher in antipsychotic-naive first-episode paranoid schizophrenics (n = 47) than healthy controls (n = 84), dementia patients (n = 13) or affective disorder patients (n = 22). Such an alteration is absent in schizophrenics treated with 'typical' antipsychotics (n = 37), which antagonize dopamine D2-like receptors, but not in those treated with 'atypical' antipsychotics (n = 34), which preferentially antagonize 5HT(2A) receptors. Furthermore, we found that, in nonmedicated acute schizophrenics, CSF anandamide is negatively correlated with psychotic symptoms (rS = -0.452, P = 0.001). The results suggest that anandamide elevation in acute paranoid schizophrenia may reflect a compensatory adaptation to the disease state.

Polyunsaturated fatty acid levels in red cell membranes of unmedicated schizophrenic patients

There are several reports of reduced levels of polyunsaturated fatty acids (PUFA), particularly arachidonic acid (AA) and docosahexaenoic acid (DHA), in membrane phospholipid from various tissues including red blood cells (RBC) taken from schizophrenic patients. However, reports have not been entirely consistent and most studies have been confounded by the potential effects of environmental factors including antipsychotic medication and diet. We measured PUFA levels in RBC from two separate groups of unmedicated patients and control subjects from India and Malaysia, populations which have substantial differences in diet. We found no significant difference in levels of AA between patients and control subjects in either population. Levels of adrenic acid were significantly reduced, and levels of DHA significantly increased in both clinical populations. However, diet-related differences in DHA between the populations from India and Malaysia were much greater than differences between schizophrenic patients and controls. It is concluded that reduced RBC membrane levels of AA and DHA are not pathognomic of schizophrenia but that variations in cell membrane fatty acid levels are an epiphenomenon which may reflect underlying abnormalities of phospholipid and fatty acid metabolism and their interaction with environmental factors including medication and diet.

Eicosapentaenoic acid-rich essential fatty acid supplementation in chronic fatigue syndrome associated with symptom remission and structural brain changes

Lateral ventricular enlargement has been reported in chronic fatigue syndrome, while cerebral neurospectroscopy has recently indicated that essential fatty acid treatment may be of value in this condition. An essential fatty acid supplement rich in eicosapentaenoic acid (EPA) was therefore given daily to a female patient with a 6-year history of unremitting symptoms of chronic fatigue syndrome. Cerebral magnetic resonance scanning was carried out at baseline and 16 weeks later. The EPA-rich essential fatty acid supplementation led to a marked clinical improvement in her symptoms of chronic fatigue syndrome, starting within 6-8 weeks. Accurate quantification of the lateral ventricular volumes in the baseline and 16-week follow-up registered images of high-resolution magnetic resonance imaging structural scans showed that the treatment was accompanied by a marked reduction in the lateral ventricular volume during this period, from 28,940-23,660 mm3.

Clinical potential of omega-3 fatty acids in the treatment of schizophrenia

The phospholipids in the neuronal membranes of the brain are rich in highly unsaturated essential fatty acids (EFAs). It has been hypothesised that abnormalities of phospholipid metabolism are present in patients with schizophrenia and that the EFAs omega-3 polyunsaturated fatty acids, and eicosapentaenoic acid (EPA) in particular, may have a role in treating this illness. Considerable preclinical and clinical evidence provides support for this proposal. An epidemiological study reported a better outcome for patients with schizophrenia in countries where the diet is rich in unsaturated fatty acids. Evidence of abnormalities of EFAs has been found in erythrocyte membranes and cultured skin fibroblasts of patients with schizophrenia, and abnormal retinal function and niacin skin flush tests (markers of omega-3 polyunsaturated fatty acid depletion) have also been reported. Case reports and an open-label clinical trial reported efficacy for EPA in schizophrenia. Four randomised, controlled trials of EPA versus placebo as supplemental medication have now been reported. Two of these trials showed significant benefit with EPA on the positive and negative symptom scale total scores, whereas the other two did not show any effects on this primary efficacy measure. One study also reported a beneficial effect on dyskinesia. In the only published trial in which EPA was used as monotherapy versus placebo in schizophrenia, some evidence was found to suggest antipsychotic activity. Taken together, there is considerable evidence to suggest abnormalities of EFAs in cell membranes of patients with schizophrenia, and there is preliminary evidence that EPA is an effective adjunct to antipsychotics.

From membrane phospholipid defects to altered neurotransmission: is arachidonic acid a nexus in the pathophysiology of schizophrenia?

Schizophrenia (SZ) is a devastating neuropsychiatric disorder affecting 1% of the general population, and is characterized by symptoms such as delusions, hallucinations, and blunted affect. While many ideas regarding SZ pathogenesis have been put forth, the majority of research has focused on neurotransmitter function, particularly in relation to altered dopamine activity. However, treatments based on this paradigm have met with only modest success, and current medications fail to alleviate symptoms in 30-60% of patients. An alternative idea postulated a quarter of a century ago by Feldberg (Psychol. Med. 6 (1976) 359) and Horrobin (Lancet 1 (1977) 936) involves the theory that SZ is associated in part with phospholipid/fatty acid abnormalities. Since then, it has been repeatedly shown that in both central and peripheral tissue, SZ patients demonstrate increased phospholipid breakdown and decreased levels of various polyunsaturated fatty acids (PUFAs), particularly arachidonic acid (AA). Given the diverse physiological function of membrane phospholipids and PUFAs, an elucidation of their role in SZ pathophysiology may provide novel strategies in the treatment of this disorder. The purpose of this review is to summarize the relevant data on membrane phospholipid/PUFA defects in SZ, the physiological consequence of altered AA signaling, and how they relate to the neurobiological manifestations of SZ and therapeutic outcome.

Decreased antioxidant enzymes and membrane essential polyunsaturated fatty acids in schizophrenic and bipolar mood disorder patients

Oxidative stress-mediated cell damage has been considered in the pathophysiology of schizophrenia. Abnormal findings have often been considered related to differences in ethnicity, life style, dietary patterns and medications, all of which influence indices of oxidative stress and oxidative cell damage. To minimize these confounds, schizophrenic patients were compared with age-matched control subjects with the same ethnic background and similar lifestyle, as well as with bipolar mood disorder (BMD) patients. Levels of antioxidant defense enzymes (i.e. superoxide dismutase, SOD; catalase, CAT; and glutathione peroxidase, GPx) were lower in schizophrenic patients than in controls, indicating conditions for increased oxidative stress. The contents of plasma thiobarbituric acid reactive substances (TBARS) were only marginally higher in schizophrenic patients, who had normal levels of arachidonic acid (AA), a major source of TBARS, indicating no significant oxidative membrane lipid peroxidation. Levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), however, were significantly lower in schizophrenic patients. When the same indices in BMD patients were compared with findings in matched controls, levels of only SOD and CAT were lower in the patients, whereas GPx was not. Again, as in schizophrenia, the contents of TBARS were marginally higher in BMD patients with no change in levels of AA. Levels of alpha-linolenic acid and EPA were significantly lower and levels of DHA were slightly lower in BMD patients. These data indicate that certain biochemical characteristics may be common to a spectrum of psychiatric disorders, and suggest supplementation of antioxidants and essential fatty acids might affect clinical outcome.

Eicosapentaenoic acid in the treatment of schizophrenia and depression: rationale and preliminary double-blind clinical trial results

It has been hypothesised that polyunsaturated fatty acids (PUFA) play an important role in the aetiology of schizophrenia and depression. Evidence supporting this hypothesis for schizophrenia includes abnormal brain phospholipid turnover shown by 31P Magnetic Resonance Spectroscopy, increased levels of phospholipase A2, reduced niacin skin flush response, abnormal electroretinogram, and reduced cell membrane levels of n-3 and n-6 PUFA. In depression, there is strong epidemiological evidence that fish consumption reduces risk of becoming depressed and evidence that cell membrane levels of n-3 PUFA are reduced. Four out of five placebo-controlled double- blind trials of eicosapentaenoic acid (EPA) in the treatment of schizophrenia have given positive findings. In depression, two placebo-controlled trials have shown a strong therapeutic effect of ethyl-EPA added to existing medication. The mode of action of EPA is currently not known, but recent evidence suggests that arachidonic acid (AA) if of particular importance in schizophrenia and that clinical improvement in schizophrenic patients using EPA treatment correlates with changes in AA.

Membrane polyunsaturated fatty acids and CSF cytokines in patients with schizophrenia

Findings to date provide evidence that altered membrane structure and function are present in patients with either first-episode or chronic schizophrenia, suggesting defects in phospholipid metabolism and cell signaling in schizophrenia. The purpose of this investigation is to test whether decreased membrane polyunsaturated fatty acids (PUFAs) were associated with an increased secretion of proinflammatory cytokines. Thus, we measured interleukin 6 (IL-6) and interleukin 10 (IL-10) in cerebrospinal fluid (CSF) of patients with chronic schizophrenia as well as PUFAs of red blood cell (RBC) membranes from the same individuals. A significant and inverse correlation was found between CSF IL-6 (not IL-10) and RBC membrane PUFAs levels in both haloperidol-treated and medication-free patients with schizophrenia. Specifically, such an association was found in the n-6 (18:2, 20:4, and 22:4) and, to a lesser extent, the n-3 fatty acids. Taken together, the present findings suggest that decreased membrane PUFAs may be related to an immune disturbance in schizophrenia, possibly resulting from an increased phospholipase A2 activity mediated through the proinflammatory cytokines.

Red blood cell membrane essential fatty acid metabolism in early psychotic patients following antipsychotic drug treatment

A role of indices of oxidative stress, oxidative injury, and abnormal membrane phospholipid, specifically the phospholipid essential polyunsaturated fatty acids (EPUFAs) metabolism has been suggested based on studies in separate groups of patients with or without medication. The current study investigated the relationship between these biochemical measures in first-episode psychotic patients (N=16) at baseline and after 6 months of antipsychotic treatment (N=5 each with risperidone and olanzapine) and compared them to matched normal subjects. The indices of oxidative stress included: antioxidant enzymes; superoxide dismutase, glutathione peroxidase and catalase; and the oxidative injury as the levels of plasma lipid peroxides. The key membrane EPUFA's been; linolenic acid, arachidonic acid, nervonic acid, docosapentaenoic acid and docosahexaenoic acid. Furthermore, the changes in these biochemical measures were correlated with clinical symptomatology. Data indicated that, at baseline, reduced levels of antioxidant enzymes were associated with increased plasma lipid peroxides and reduced membrane EPUFAs, particularly omega-3 fatty acids. Furthermore, these biochemical measures normalized after 6 months of antipsychotic treatment. Parallel-improved psychopathology indicated that membrane EPUFA status might be partly affected by oxidative damage, which together may contribute to the pathophysiology and thereby, psychopathology of schizophrenia. These data also support the augmentation of antipsychotic treatment by supplementation with a combination of antioxidants and omega-3 fatty acids.

Phospholipid and eicosanoid signaling disturbances in schizophrenia

A variety of biochemical, clinical and genetic evidence suggests that phospholipid metabolism may play an aetiological role in schizophrenia. A key piece of evidence is the reduced vasodilatory response of patients with schizophrenia to nicotinic acid (NA). NA causes vasodilation via the activation of phospholipase A2 (PLA2) leading to the release of free fatty acids from membrane phospholipids and the subsequent production of prostaglandins. Insensitivity to NA may be due to a 'block' in the downstream signaling pathway used by the drug to evoke its response. It can be argued that if such an abnormality occurs in neurons, impaired PLA2-dependent signaling could result in altered glutamateric and dopaminergic transmission in such a way as to produce or exacerbate psychotic symptoms. The complimentary finding of increased PLA2 activity in schizophrenia may be an attempt to overcome the signaling block. It is suggested that intervention aimed at increasing the activity of PLA2-dependent signaling systems may be therapeutically useful in the treatment of the illness.

Antipsychotic drug treatment alters expression of mRNAs encoding lipid metabolism-related proteins

Using an automated PCR-based genomics approach, TOtal Gene expression Analysis (TOGA), we have examined gene expression profiles of mouse striatum and frontal cortex in response to clozapine and haloperidol drug treatment. Of 17 315 mRNAs observed, TOGA identified several groups of related molecules that were regulated by drug treatment. The expression of some genes encoding proteins involved in neurotransmission, signal transduction, oxidative stress, cell adhesion, apoptosis and proteolysis were altered in the brains of both clozapine- and haloperidol-treated mice as recognized by TOGA. Most notable was the differential expression of those genes whose products are associated with lipid metabolism. These include apolipoprotein D (apoD), the mouse homolog of oxysterol-binding protein-like protein 8 (OSBPL8), a diacylglycerol receptor (n-chimerin), and lysophosphatidic acid (LPA) acyltransferase. Real-time PCR analysis confirmed increases in the RNA expression of apoD (1.6-2.2-fold) and OSBPL8 (1.7-2.6-fold), and decreases in the RNA expression of n-chimerin (1.5-2.2-fold) and LPA acyltransferase (1.5-fold) in response to haloperidol and/or clozapine treatment. Additional molecules related to calcium homeostasis and signal transduction, as well as four sequences of previously unidentified mRNAs, were also confirmed by real-time PCR to be regulated by drug treatment. While antipsychotic drugs may affect several metabolic pathways, lipid metabolism/signaling pathways may be of particular importance in the mechanisms of antipsychotic drug action and in the pathophysiology of psychiatric disorders.

Docosahexaenoic acid (DHA) content of membranes determines molecular activity of the sodium pump: implications for disease states and metabolism

The omega-3 polyunsaturate, docosahexaenoic acid (DHA), plays a number of biologically important roles, particularly in the nervous system, where it is found in very high concentrations in cell membranes. In infants DHA is required for the growth and functional development of the brain, with a deficiency resulting in a variety of learning and cognitive disorders. During adulthood DHA maintains normal brain function and recent evidence suggests that reduced DHA intake in adults is linked with a number of neurological disorders including schizophrenia and depression. Here we report a high positive correlation between the molecular activity (ATP min(-1)) of individual Na(+)K(+)ATPase units and the content of DHA in the surrounding membrane bilayer. This represents a fundamental relationship underlying metabolic activity, but may also represent a link between reduced levels of DHA and neurological dysfunction, as up to 60% of energy consumption in the brain is linked to the Na(+)K(+)ATPase enzyme.

Potential role of dietary omega-3 essential fatty acids on some oxidant/antioxidant parameters in rats' corpus striatum

Omega-3 (omega-3) is an essential fatty acid (EFA) found in large amounts in fish oil. It contains eicosapentaenoic acid and docosahexaenoic acid (DHA). DHA is one of the building structures of membrane phospholipids of brain and necessary for continuity of neuronal functions. Evidences support the hypothesis that schizophrenia may be the result of increased reactive oxygen species mediated neuronal injury. Recent reports also suggest the protective effect of omega-3 EFA against neuropsychiatric disorders including schizophrenia. This study proposed to assess the changes in antioxidant enzyme and oxidant parameters in the corpus striatum (CS) of rats fed with omega-3 EFA diet (0.4g/kg/day) for 30 days. Eight control rats and nine rats fed with omega-3 were decapitated under ether anesthesia, and CS was removed immediately. Thiobarbituric acid-reactive substances (TBARS) and nitric oxide (NO) levels as well as total superoxide dismutase (t-SOD) and xanthine oxidase (XO) enzyme activities in the CS were measured. Rats treated with omega-3 EFA had significantly lower values of TBARS (P<0.001), NO (P<0.002) and XO (P<0.005) whereas higher values of t-SOD enzyme activity (P<0.002) than the control rats. These results indicate that omega-3 EFA rich fish oil diet reduces some oxidant parameters in CS. This may be revealed by means of reduced CS TBARS levels as an end product of lipid peroxidation of membranes in treated rats. Additionally, reduced XO activity and NO levels may support this notion. On the other hand, although the mechanism is not clear, omega-3 EFA may indirectly enhance the activity of antioxidant enzyme t-SOD. Taken together, this preliminary animal study provides strong support for a therapeutic effect of omega-3 EFA supplemented to classical neuroleptic regimen in the treatment of schizophrenic symptoms and tardive dyskinesia.

Antipsychotic drugs differentially modulate apolipoprotein D in rat brain

Apolipoprotein-D (apoD), a member of the lipocalin family of proteins, binds to arachidonic acid and cholesterol among other hydrophobic molecules. Recently, elevated apoD levels have been reported in the post-mortem brains, as well as plasma, of schizophrenic patients and in rodent brains after chronic treatment with clozapine (CLOZ). These findings and the evidence for altered membrane lipid metabolism in schizophrenia suggest that apoD may have a role in the pathophysiology of illness, and also in the differential clinical outcome following treatment with typical and atypical antipsychotic drugs. Here, we compared the effects of these antipsychotics on the expression of apoD in rat brain. Chronic treatment with typical antipsychotic, haloperidol (HAL) reduced apoD expression in hippocampus, piriform cortex and caudate-putamen (p = 0.027-0.002), whereas atypical antipsychotics, risperidone (RISP) and olanzapine (OLZ) increased (p = 0.051 to < 0.001 and p = 0.048 to < 0.001, respectively) apoD expression. In hippocampus, HAL-induced changes were present in CA1, CA3 and dentate gyrus, however, apoD levels in motor cortex were unchanged. There were also very dramatic effects of HAL on the neuronal morphology, particularly, cellular shrinkage and disorganization with the loss of neuropil. Post-treatment, either with RISP or OLZ, was very effective in restoring the HAL-induced reduction of apoD, as well as cellular morphology. Similarly, pre-treatments were also effective, but slightly less than post-treatment, in preventing HAL-induced reduction of apoD. The increased expression of apoD by atypical antipsychotics may reflect a novel molecular mechanism underlying their favorable effects compared with HAL on cognition, negative symptoms and extra-pyramidal symptoms in schizophrenia.

Fluorometric assays of phospholipase A2 activity with three different substrates in biological samples of patients with schizophrenia

The rationale of this study was to understand the complexity of kinetics of fluorogenic phospholipid substrates as well as contradictory findings of clinical papers measuring phospholipase A2 (PLA2) activity using different methodologies. The aim was to recommend to clinicians and researchers what substrate in conjunction with what assay should be used. Two methods, (i) continuous fluorometric assay and (ii) high performance thin layer chromatography (HPTLC) on microplates combined with quantitative image scanning, were studied with three different substrates (bis-BODIPY FL C11-PC, NBDC6-HPC, PED6). The study demonstrates that NBD-PC is not a suitable substrate to measure PLA2 activity using a spectrofluorometer. On the other hand, NBD-PC gives the highest and most reproducible integrated light intensities (ILls) in HPTLC studies. Slow time-dependent increases in fluorescence intensities recorded with biological samples in fluorometers, but not caused by substrate splitting, had to be classified as "perturbation kinetics". PLA2 activities in blood samples of 26 unmedicated schizophrenia patients and 26 age-matched healthy controls were measured by the spectrofluorometric method and then compared with the activity data obtained with the HPTLC method. A significant group difference was found only with the HPTLC. In order to get more reliable results, we recommend that clinicians and researchers use NBD-phosphatidylcholines as PLA2 substrates in biological samples and start with an analytical separation of reaction products followed by image analysis of the fluorescent spots.

Potential use of the topical niacin skin test in early psychosis -- a combined approach using optical reflection spectroscopy and a descriptive rating scale

The niacin skin phenomenon reflects a prostaglandin (PG) mediated flush and oedema reaction. As PG metabolism is linked to breakdown of membrane lipids, diminished sensitivity to niacin application suggests potential disturbance in membrane phospholipid-arachidonic acid-PG pathways. We aimed to evaluate and quantify topical niacin skin reaction in early psychosis using optical reflection spectroscopy (ORS) and a new descriptive assessment scale integrating time course, redness, and oedema. Niacin skin tests were performed on 25 medicated first-episode psychosis patients fulfilling DSM-IV criteria for schizophreniform psychosis or schizophrenia and on 25 healthy controls. Nicotinic acid was applied in four dilution steps to the subjects inner forearm skin and skin reaction was consecutively assessed using ORS and a seven point rating scale. Both descriptive ratings and spectroscopic measures revealed significant group differences at the lower niacin concentrations (0.001 and 0.0001 M). At higher concentrations (0.01 and 0.1 M) only descriptive ratings were capable to show significant group effects. Data of both methods showed moderate to strong correlation (r=0.605) as long as the erythema was not affected by the oedema. The data suggest that niacin sensitivity is inversely correlated with negative symptoms. Both methods demonstrate that niacin sensitivity is impaired in a group of first episode psychosis patients and are therefore able to distinguish a subgroup of patients with metabolic impairment. Niacin sensitivity in high risk populations and the specificity of impaired skin response are subjects of further investigation.

Inadequate levels of essential nutrients in developed nations as a risk factor for disease: a review

Inadequate levels of essential nutrients is a most important factor in environmental health, leading to an almost monotonic increase in the incidence, morbidity, mortality, and associated costs of 'diseases of affluence' that has persisted for circa a century. Such an unprecedented human tragedy can be explained by the (1) flawed belief that essential nutrients can be replaced by xenobiotic molecules--a fundamental error, (2) failure to recognize that the levels of certain essential nutrients in diets available in the environment are not adequate to produce optimum health, longevity or resistance, and (3) failure to recognize that the refined diet has a lower essential nutrient content. Such beliefs contribute to early death in affluent nations.

Smoking, gender, and dietary influences on erythrocyte essential fatty acid composition among patients with schizophrenia or schizoaffective disorder

BACKGROUND

Prior reports of decreased levels of essential fatty acids among schizophrenic patients have generated several hypotheses proposing inherent abnormalities in phospholipid and fatty acid metabolism and have provided the basis for treatment trials; however, these essential fatty acid aberrations may be attributable to uncontrolled factors, such as smoking, rather than abnormalities inherent to schizophrenia.

METHODS

Erythrocyte fatty acid compositions were quantified in 72 medicated schizophrenic or schizoaffective patients both at baseline and after 16 weeks of supplementation with 3 g/day of either ethyl-eicosapentaenoic acid or placebo. Current smoking status, gender, dietary survey, and Montgomery Asburg Depression Rating Scale, Repeatable Battery for the Assessment of Neuropsychological Status, Abnormal Involuntary Movement Scale, and Positive and Negative Syndrome Scale scores were assessed.

RESULTS

Schizophrenic patients who smoked had lower baseline erythrocyte docosahexaenoic acid percent (2.98 +/-.7 vs. 3.59 +/- 1.2, p <.005) and eicosapentaenoic acid (EPA) percent (.39 +/-.13 vs. 47 +/-.22, p <.05), compared with nonsmokers, with a significant gender interaction (p <.01) in multivariate analyses of variance. Baseline arachidonic acid did not differ. Smokers reported lower dietary intake (percent total fat) of linolenic acid (F = 10.1, p <.003) compared with nonsmokers. Nonsmoking women reported greater dietary intake of EPA compared with smoking men or nonsmokers of either gender.

CONCLUSIONS

Smoking status, gender, and dietary intake significantly predicted erythrocyte polyunsaturated fatty acid status among schizophrenic patients. No evidence was found for subgroups of schizophrenia or relationships to specific symptom severity on the basis of erythrocyte fatty acids. Prior reports of abnormalities of essential fatty acid metabolism among schizophrenic patients may have been an artifact of patients' smoking behavior and differences in dietary intake of omega-3 fatty acids.

Is schizophrenia a metabolic brain disorder? Membrane phospholipid dysregulation and its therapeutic implications

The dysregulation of membrane phospholipid metabolism exists throughout the body from the onset of psychosis in schizophrenic patients. This dysregulation is primarily due to altered contents of phospholipid bound EPUFAs, AA and DHA. These EPUFAs are highly enriched in the brain and are crucial for brain and behavioral development. A phospholipid metabolic defect may preexist the onset of psychosis, even through early embryonic stages. Because these membrane phospholipids play a crucial role in the membrane receptor-mediated signal transduction of several neuro-transmitters and growth factors, their altered metabolism may contribute to the reported abnormal information processing in schizophrenia. Severity of symptoms seems to correlate with the membrane AA and DHA status, which is influenced by patients' dietary intake and lifestyle. Such a metabolic defect can be prevented, however, and some membrane pathology can be corrected by dietary supplementation with a combination of AA and DHA and antioxidants such as vitamins E and C. In schizophrenia, it may be advisable to provide supplementation at the early stages of illness, when brain has a high degree of plasticity. Finally, at this time, supplementation has to be considered as an augmentation of conventional antipsychotic treatment.

Reduction of synapsin in the hippocampus of patients with bipolar disorder and schizophrenia

Several studies suggest that decreased expression of presynaptic proteins may be characteristic of schizophrenia. We examined one such protein, synapsin, in schizophrenia and bipolar disorder. Samples of hippocampal tissue from controls (n = 13), patients with schizophrenia (n = 16), or bipolar disorder (n = 6), and suicide victims (n = 7) were used. The membrane and cytosolic fractions were analyzed by Western immunoblotting for synapsin using an antibody that detects synapsin Ia, IIa, and IIIa proteins. Synaptophysin was also measured for comparison. Total synapsin was decreased significantly in patients with schizophrenia (P = 0.034) and in bipolar disorder (P = 0.00008) as compared to controls. The synapsin/synaptophysin ratios were decreased in schizophrenia and bipolar disorder, and additionally in suicide victims (P = 0.014). Age, postmortem interval, percentage of protein extracted, and pH of brain were not different between groups. No changes in total synapsin or synaptophysin in the hippocampus were produced by injecting rats with either lithium or haloperidol for 30 days. Reductions in synapsin in both patients with schizophrenia (synapsin IIa and IIIa) and bipolar disorder (synapsin Ia, IIa and IIIa) imply that altered or reduced synaptic function in the hippocampus may be involved in these disorders.

Essential polyunsaturated fatty acid and lipid peroxide levels in never-medicated and medicated schizophrenia patients

BACKGROUND

Reduced levels of membrane essential polyunsaturated fatty acids (EPUFAs) and increased levels of lipid peroxidation products (thiobarbituric acid reactive substances; TBARS) have been observed in chronic medicated schizophrenics. The relationship of EPUFA and TBARS to psychopathology is unclear, since their levels may be altered differentially by duration of illness and antipsychotic treatment. To minimize these confounds, their levels were compared among never-medicated patients in early illness, medicated patients and control subjects with similar lifestyle and common ethnic background.

METHODS

RBC membrane EPUFAs, plasma TBARS, and various dimensions of psychopathology were measured using established procedures in never-medicated (n = 20) and medicated (n= 32) schizophrenia patients and in control subjects (n= 45).

RESULTS

Reduced levels of EPUFAs, particularly arachidonic acid (AA) and docosahexaenoic acid (DHA), were found in never-medicated compared with control subjects; however, the reductions in levels of both AA and DHA were much smaller in medicated versus never-medicated patients; AA levels were similar to levels in control subjects. Only DHA levels were significantly reduced in medicated patients. Lower membrane AA levels were associated with increased levels of plasma TBARS in never-medicated patients. Lower levels of membrane EPUFAs and higher levels of plasma TBARS were associated with the severe symptoms in never-medicated versus medicated patients.

CONCLUSIONS

Data indicate that reduced EPUFAs and increased TBARS exist in never-medicated patients, and these measures correlate with the severity of psychopathology indicating that the membrane EPUFA status may reflect the outcome of schizophrenia.

A common role for psychotropic medications: memory impairment

The psychopathologic profile of mental disorders is very diverse and psychotropic medications used to treat them differ in their chemical structure. Nevertheless, these drugs share these four characteristics: delayed onset of clinical response, not one of them can be said to cure, there is a high number of non-responders, and the mechanism responsible for their therapeutic action is not known. It is hypothesized that the action of psychotropic medications is memory impairment, understanding memory as the trace left in the nervous system not only by individual experiences but also by genetic and epigenetic phenomena. It is suggested that it would be beneficial to translate some research strategies from the neurobiology of learning and memory to the study of the effects of psychotropic medications. The hypothesis is briefly assessed according to the following three criteria: (a). the comparison between the molecular effects of psychotropic medications and the so-called molecular biology of learning and memory, (b). the effects of these drugs, preferentially after chronic use, on memory tests, and (c). the effects of drugs that impair memory on tests used for screening psychotropic medications. Finally, some general suggestions for future research are pointed out.

Prediction and prevention of transition to psychosis in young people at incipient risk for schizophrenia

The treatment of psychotic disorders, particularly schizophrenia, had been viewed with pessimism until a recent shift in focus from established or chronic illness to earlier phases of illness around the onset highlighted opportunities for enhanced recovery. Associated with this change in focus of research and clinical efforts has been the recognition that the biological and social changes underpinning the development of psychotic disorders may already be active in the pre-psychotic or prodromal phase. It has therefore been suggested that efforts toward the prevention of psychotic disorders should focus on the emerging illness. This article provides a review of work that has been conducted at the PACE Clinic in Melbourne, Australia since 1994. This clinical research program was established to develop strategies for the identification of young people at high risk of developing a psychotic disorder within a short period of time- primarily by virtue of recent mental state changes. Additionally, biological and psychological processes that have been proposed to underlie the development of illness have been investigated and potential preventive interventions have been evaluated.

The neurobiology of apolipoproteins in psychiatric disorders

A genetic contribution to the transmission of psychiatric disorders has been established and it is now accepted that several genes confer susceptibility to schizophrenia, and similar disorders, giving rise to a complex polygenic mode of inheritance. With the high-throughput molecular profiling techniques available, apolipoproteins have emerged as being important factors in psychiatric disorders. This review will focus on three apolipoproteins that have recently been shown to be elevated in neuropsychiatric disorders: apoD, apoE, and apoL. Furthermore, the authors discuss the role of apoD in the pathology and pharmacotherapy of schizophrenia and bipolar disorder.

Reduction of the synaptophysin level but normal levels of glycerophospholipids in the gyrus cinguli in schizophrenia

The 'membrane hypothesis' of schizophrenia postulates a disturbance in the metabolism and structure of membrane phospholipids resulting in a disturbance in the function of neuronal membrane proteins. Most studies exploring this hypothesis have examined components of peripheral blood. Since it may be questioned if these peripheral measurements reflect changes in the brain, we studied the fatty acid composition of glycerophospholipids in brain tissue. As a marker for synaptic density, we also measured the synaptic vesicle protein synaptophysin. Brain tissue (gyrus cinguli) from 11 schizophrenic patients (mean age 80 +/- 10 years) and 13 controls (mean age 75 +/- 14 years) was examined. The glycerophospholipid fatty acids were determined by gas chromatography. Synaptophysin protein level was determined using quantitative immunoblotting followed by Western blotting. There were no significant differences between the groups in the total or in any individual level of fatty acids, either in the n - 6 or n - 3 series. The level of synaptophysin was significantly p = (0.002) decreased in the schizophrenic group(0.73 + 0.18) as compared with the control group (1.02 + 0.21). The normal pattern and concentration of glycerophospholipids fatty acids found in the present study do not support the membrane hypothesis of schizophrenia. The possibility of a type II error should, however. be considered. On the other hand, the reduced synaptophysin' levels in the gyrus cinguli demonstrate that biological differences can be revealed in this relatively small sample. This also lends further support to the notion that a synaptic disturbance or loss is of importance in the pathogenesis of schizophrenia.

Brain-specific lipids from marine, lacustrine, or terrestrial food resources: potential impact on early African Homo sapiens

The polyunsaturated fatty acid (PUFA) composition of the mammalian central nervous system is almost wholly composed of two long-chain polyunsaturated fatty acids (LC-PUFA), docosahexaenoic acid (DHA) and arachidonic acid (AA). PUFA are dietarily essential, thus normal infant/neonatal brain, intellectual growth and development cannot be accomplished if they are deficient during pregnancy and lactation. Uniquely in the human species, the fetal brain consumes 70% of the energy delivered to it by mother. DHA and AA are needed to construct placental and fetal tissues for cell membrane growth, structure and function. Contemporary evidence shows that the maternal circulation is depleted of AA and DHA during fetal growth. Sustaining normal adult human brain function also requires LC-PUFA.Homo sapiens is unlikely to have evolved a large, complex, metabolically expensive brain in an environment which did not provide abundant dietary LC-PUFA. Conversion of 18-carbon PUFA from vegetation to AA and DHA is considered quantitatively insufficient due to a combination of high rates of PUFA oxidation for energy, inefficient and rate limited enzymatic conversion and substrate recycling. The littoral marine and lacustrine food chains provide consistently greater amounts of pre-formed LC-PUFA than the terrestrial food chain. Dietary levels of DHA are 2.5-100 fold higher for equivalent weights of marine fish or shellfish vs. lean or fat terrestrial meats. Mammalian brain tissue and bird egg yolks, especially from marine birds, are the richest terrestrial sources of LC-PUFA. However, land animal adipose fats have been linked to vascular disease and mental ill-health, whereas marine lipids have been demonstrated to be protective. At South African Capesites, large shell middens and fish remains are associated with evidence for some of the earliest modern humans. Cape sites dating from 100 to 18 kya cluster within 200 km of the present coast. Evidence of early H. sapiens is also found around the Rift Valley lakes and up the Nile Corridor into the Middle East; in some cases there is an association with the use of littoral resources. Exploitation of river, estuarine, stranded and spawning fish, shellfish and sea bird nestlings and eggs by Homo could have provided essential dietary LC-PUFA for men, women, and children without requiring organized hunting/fishing, or sophisticated social behavior. It is however, predictable from the present evidence that exploitation of this food resource would have provided the advantage in multi-generational brain development which would have made possible the advent of H. sapiens. Restriction to land based foods as postulated by the savannah and other hypotheses would have led to degeneration of the brain and vascular system as happened without exception in all other land based apes and mammals as they evolved larger bodies.

A randomised, placebo-controlled, double blind study of treatment of Huntington's disease with unsaturated fatty acids

Huntington's Disease (HD) is a serious dominantly inherited neurodegenerative disorder for which there are no current treatments. Open label and animal studies have suggested that highly unsaturated fatty acids (HUFAs) may be beneficial. Seventeen patients with HD were entered into a randomised, placebo-controlled, double blind trial of HUFA therapy. Patients were assessed on the Rockland-Simpson Dyskinesia Rating Scale (RSDRS) and the Unified Huntington's Disease Rating Scale (UHDRS). On the RSDRS and the UHDRs motor scale patients on HUFA treatment improved while those on placebo deteriorated, with a significant difference between the two groups on the RSDRS. A similar trend was noted on the UHDRS functional performance scales. Little change was seen on the neuropsychology scales. There were no treatment-related adverse events. This is the first time that a significant improvement has been noted in a randomised trial in HD. The results are consistent with open label observations; a second placebo-controlled study in end-stage patients, and a study in a transgenic mouse model of HD.

A dose-ranging exploratory study of the effects of ethyl-eicosapentaenoate in patients with persistent schizophrenic symptoms

The objective was to test effects of ethyl eicosapentaenoate (E-E) on persistent ongoing symptoms in patients receiving different types of anti-schizophrenic drugs, typical antipsychotics, new atypical antipsychotics, and clozapine. 115 patients with DSM-IV-defined schizophrenia were studied, 31 on clozapine, 48 on new atypical drugs and 36 on typical antipsychotics. Placebo or 1, 2 or 4 g/day of E-E was given for 12 weeks in addition to the background medication. The main assessment was change from baseline to 12 weeks on the PANSS and its sub-scales. There were no treatment-related side effects or adverse biochemical or haematological effects. Patients on 2 and 4 g/day E-E showed significant reductions in triglyceride levels which had been elevated by clozapine. In patients given 2 g/day E-E there were improvements on the PANSS and its sub-scales, but there was also a large placebo effect in patients on typical and new atypical antipsychotics and no difference between active treatment and placebo. In patients on clozapine, in contrast, there was little placebo response, but a clinically important and statistically significant effect of E-E on all rating scales. This effect was greatest at 2 g/day. There was a positive relationship between improvement on rating scales and rise in red blood cell arachidonic acid concentration.

A volumetric biochemical niacin flush-based index that noninvasively detects fatty acid deficiency in schizophrenia

(1) It is possible to investigate aspects of phospholipid-related signal transduction in humans noninvasively using the niacin skin flush test. (2) Patients with schizophrenia have previously been reported to show a reduced flushing response. (3) The aim of this study was to devise a comprehensive index of cutaneous response to the niacin test, incorporating aqueous methyl nicotinate concentration and time, and to test this index in schizophrenia. (4) A discrete approximation to a continuous volumetric index, which we have named the volumetric niacin response (VNR), was devised. Its value was measured in 27 patients with DSM-IV schizophrenia and 26 age- and sex-matched normal controls. (5) The mean value of the VNR in the patients with schizophrenia (16.26) was significantly smaller than that of 26.77 in the normal controls (P<.0004). (6) With a threshold value for the VNR of 21, the test differentiated well between schizophrenia and normal controls (P=.002) with a sensitivity of 78% and a specificity of 65%. (7) The present results confirm that the flushing response is reduced in schizophrenia, and show that calculation of the VNR is an effective means of allowing the total response in different patients or patient groups to be readily compared.

Molecular activity of Na+/K+-ATPase from different sources is related to the packing of membrane lipids

The activity of the ubiquitous Na+/K+-ATPase represents a substantial portion of the resting metabolic activity of cells, and the molecular activity of this enzyme from tissues of different vertebrates can vary several-fold. Microsomes were prepared from the kidney and brain of the rat (Rattus norvegicus) and the cane toad (Bufo marinus), and Na+/K+-ATPase molecular activity was determined. The membrane lipids surrounding this enzyme were isolated and phospholipids prepared. ‘Surface pressure/area’ isotherms were measured in monolayers for both membrane lipids and phospholipids using classic Langmuir trough techniques. Microsomal lipid composition was also measured. Whilst significant correlations were observed between membrane composition and Na+/K+-ATPase molecular activity, the strongest correlations were found between the molecular activity and parameters describing the packing of the surrounding membrane lipids and phospholipids. The influence of membrane lipid composition, especially membrane acyl composition, on the activity of a membrane protein mediated by physical properties of the lipids may represent a fundamental principle applicable to other membrane proteins.

Manic depressive psychosis and schizophrenia are neurological disorders at the extremes of CNS maturation and nutritional disorders associated with a deficit in marine fat

The maturational theory of brain development comprises manic depressive psychosis and schizophrenia. It holds that the disorders are part of human diversity in growth and maturation, which explains their ubiquity, shared susceptibility genes and multifactorial inheritance. Rate of maturation and age at puberty are the genotype; the disorders are localized at the extremes with normality in between. This is based on the association between onset of puberty and the final regressive event, with pruning of 40% of excitatory synapses leaving the inhibitory ones fairly unchanged. This makes excitability, a fundamental property of nervous tissue, a distinguishing factor: the earlier puberty, the greater excitability--the later puberty, the greater deficit. Biological treatment supports deviation from the norm: neuroleptics are convulsant; antidepressives are anti-epiletogenic. There is an association between onset of puberty and body-build: early maturers are pyknic broad-built, late ones linearly leptosomic. This discrepancy is similar to that in the two disorders, supporting the theory that body-build is the phenotype. Standard of living is the environmental factor, which affects pubertal age and shifts the panorama of mental illness accordingly. Unnatural death has increased with antipsychotics. Other treatment is needed. PUFA deficit has been observed in RBC in both disorders and striking improvements with addition of minor amounts of PUFA. This supports that dietary deficit might cause psychotic development and that prevention is possible. Other neurological disorders also profit from PUFA, underlining a general deficit in the diet.

Phospholipid patterns of erythrocytes in schizophrenia: relationships to symptomatology

The phospholipid composition of red blood cells (RBC) from 32 haloperidol-treated schizophrenic patients, classified according to the positive and negative syndrome scale (PANSS) as showing either predominantly positive or predominantly negative symptoms, was determined and compared with that of normal controls. While the levels of phosphatidylcholine and phosphatidylserine were similar in all three groups, sphingomyelin (SM) and phosphatidylethanolamine (PE) were, respectively, increased and decreased in RBCs of schizophrenic patients. In both patient groups, the SM/PE ratios correlated directly with the PANSS negative symptom scale scores and inversely with the positive symptom scale scores. However, the inverse changes in the contents of SM and PE were much more expressed in the negative group. It is suggested that a main source of that difference is a higher activity of the polyunsaturated acid-selective phospholipase A(2) in the negative syndrome patients than in the positive syndrome and control groups.

Polyunsaturated fatty acids and cerebral function: focus on monoaminergic neurotransmission

More and more reports in recent years have shown that the intake of polyunsaturated fatty acids (PUFA) constitutes an environmental factor able to act on the central nervous system (CNS) function. We recently demonstrated that the effects of PUFA on behavior can be mediated through effects on the monoaminergic neurotransmission processes. Supporting this proposal, we showed that chronic dietary deficiency in alpha-linolenic acid in rats induces abnormalities in several parameters of the mesocortical and mesolimbic dopaminergic systems. In both systems, the pool of dopamine stored in presynaptic vesicles is strongly decreased. This may be due to a decrease in the number of vesicles. In addition, several other factors of dopaminergic neurotransmission are modified according to the system affected. The mesocortical system seems to be hypofunctional overall [e.g., decreased basal release of dopamine (DA) and reduced levels of dopamine D2 (DAD2) receptors]. In contrast, the mesolimbic system seems to be hyperfunctional overall (e.g., increased basal release of DA and increased levels of DAD2 receptors). These neurochemical changes are in agreement with modifications of behavior already described with this deficiency. The precise mechanisms explaining the effects of PUFA on neurotransmission remain to be clarified. For example, modifications of physical properties of the neuronal membrane, effects on proteins (receptors, transporters) enclosed in the membrane, and effects on gene expression and/or transcription might occur. Whatever the mechanism, it is therefore assumed that interactions exist among PUFA, neurotransmission, and behavior. This might be related to clinical findings. Indeed, deficits in the peripheral amounts of PUFA have been described in subjects suffering from neurological and psychiatric disorders. Involvement of the monoaminergic neurotransmission function has been demonstrated or hypothesized in several of these diseases. It can therefore be proposed that functional links exist among PUFA status, neurotransmission processes, and behavioral disorders in humans. Animal models are tools of choice for the understanding of such links. Improved prevention and complementary treatment of neurological and psychiatric diseases can be expected from these studies.

Omega-3 fatty acids as a psychotherapeutic agent for a pregnant schizophrenic patient

Because of the potential adverse events and teratogenesis of antipsychotic drugs, it is important to find a safe and effective treatment for pregnant women with severe mental illness. The membrane hypothesis of schizophrenia provides a rationale to treat symptoms of schizophrenia with omega-3 PUFAs. We report a 30-year-old married woman with chronic schizophrenia, who experienced an episode of acute exacerbation of psychotic symptoms during pregnancy. After entering into an open trial of omega-3 PUFAs monotherapy, she showed a dramatic improvement in both positive and negative symptoms of schizophrenia and a significant increase of omega-3 PUFA composition in erythrocyte membrane. There were no adverse effects in this treatment. Thus, omega-3 PUFAs could be both beneficial and therapeutic to pregnant schizophrenic women.

Plasma fatty acid levels in autistic children

Phospholipid fatty acids are major structural components of neuronal cell membranes, which modulate membrane fluidity and hence function. Evidence from clinical and biochemical sources have indicated changes in the metabolism of fatty acids in several psychiatric disorders. We examined the phospholipid fatty acids in the plasma of a population of autistic subjects compared to mentally retarded controls. Our results showed a marked reduction in the levels of 22: 6n-3 (23%) in the autistic subjects, resulting in significantly lower levels of total (n-3) polyunsaturated fatty acids (PUFA) (20%), without significant reduction in the (n-6) PUFA series, and consequently a significant increase in the (n-6)/(n-3) ratio (25%). These variations are discussed in terms of potential differences in PUFA dietary intake, metabolism, or incorporation into cellular membranes between the two groups of subjects. These results open up interesting perspectives for the investigation of new biological indices in autism. Moreover, this might have new therapeutic implications in terms of child nutrition.

Correlation between serum lipid concentrations and psychological distress

This study examines the correlations between serum lipid levels and psychological distress. There were 4444 consecutive attendees of general health clinics who participated in the study. Psychological symptoms were measured by the Taiwanese version of the Symptoms Check List 90, revised (T-SCL-90-R). Levels of fasting serum lipids, including total cholesterol, total triglycerides and high-density lipoprotein cholesterol (HDL-C), were determined. Multiple linear regression analyses, with adjustment for confounders, revealed that the concentration of HDL-C had significant inverse associations with scores of depression, somatization and phobic anxiety. Women with an HDL-C level lower than 35 mg/dl scored significantly higher on depression, interpersonal sensitivity, phobia, anxiety, somatization and aggressive hostility, while subjects with a total cholesterol concentration lower than 160 mg/dl scored significantly higher on anxiety, aggressive hostility, phobia, and psychoticism. This study provides, for the first time, comprehensive data derived from the Taiwanese population on the link between lipids and psychological symptoms, revealing a reverse correlation between depression and serum concentrations of HDL-C.

Two double-blind placebo-controlled pilot studies of eicosapentaenoic acid in the treatment of schizophrenia

Evidence that the metabolism of phospholipids and polyunsaturated fatty acids (PUFA) is abnormal in schizophrenia provided the rationale for intervention studies using PUFA supplementation. An initial open label study indicating efficacy for n-3 PUFA in schizophrenia led to two small double-blind pilot studies. The first study was designed to distinguish between the possible effects of two different n-3 PUFA: eicosapentaenoic acid (EPA) and docohexaenoic acid (DHA). Forty-five schizophrenic patients on stable antipsychotic medication who were still symptomatic were treated with either EPA, DHA or placebo for 3 months. Improvement on EPA measured by the Positive and Negative Syndrome Scale (PANSS) was statistically superior to both DHA and placebo using changes in percentage scores on the total PANSS. EPA was significantly superior to DHA for positive symptoms using ANOVA for repeated measures. In the second placebo-controlled study, EPA was used as a sole treatment, though the use of antipsychotic drugs was still permitted if this was clinically imperative. By the end of the study, all 12 patients on placebo, but only eight out of 14 patients on EPA, were taking antipsychotic drugs. Despite this, patients taking EPA had significantly lower scores on the PANSS rating scale by the end of the study. It is concluded that EPA may represent a new treatment approach to schizophrenia, and this requires investigation by large-scale placebo-controlled trials.

Neurochemical investigation of the schizophrenic brain by in vivo phosphorus magnetic resonance spectroscopy

Abnormal phospholipid metabolisms may play important roles in the pathophysiology of schizophrenia. Phosphorus magnetic resonance spectroscopy (31P-MRS) offers a new method for studying phosphorus-related metabolism in vivo. A decrease in the level of phosphomonoesters (PME) and an increase in the level of phosphodiesters (PDE) has been demonstrated in the prefrontal lobe of neuroleptic-naive schizophrenic patients. Most of the studies in medicated schizophrenic patients have shown decreased PME and/or increased PDE. The decreased PME in the frontal lobe appears to be associated with negative symptoms and poor working memory performance. 1H-decoupled 31P-MRS revealed a reduction in the phosphocholine element of PME and an elevation in the mobile phospholipids of PDE in the prefrontal region of medicated schizophrenic patients. PDE were elevated in the temporal lobes of neuroleptic-naive schizophrenic patients, and this increase was partially normalized by haloperidol administration. Data about the temporal lobes of medicated schizophrenic patients have not been consistent. Except for the reduction in the adenosine triphosphate (ATP) in the basal ganglia and the correlation between the increase in the frontal lobe phosphocreatine (PCr) and negative symptomatology, data related to changes in high-energy phosphates are contradictory. No consensus on the effect of neuroleptics on phosphorus metabolites has been achieved. Methodological problems inherent in 31P-MRS may have contributed to the confusion in understanding available data. Future directions of MRS studies are suggested in the last section of the paper.

Neurodevelopmental risk factors in schizophrenia

The authors review environmental and neurodevelopmental risk factors for schizophrenic disorders, with emphasis on minor physical anomalies, particularly craniofacial anomalies and dermatoglyphic variations. The high prevalence of these anomalies among schizophrenic subjects supports the neurodevelopmental theory of the etiology of schizophrenia, since they suggest either genetically or epigenetically controlled faulty embryonic development of structures of ectodermal origin like brain and skin. This may disturb neurodevelopment that in turn may cause these subjects to be at increased risk for the development of schizophrenia and related disorders. The precise confirmation of this theory, at least in some cases, will provide further understanding of these illnesses, allowing easy and inexpensive identification of subjects at risk and providing guidelines for the development of new pharmacological interventions for early treatment and even for primary prevention of the illness.

Phospholipid metabolism and depression: the possible roles of phospholipase A2 and coenzyme A-independent transacylase

Phospholipids make up 60 per cent of the dry weight of the brain. They are essential for neuronal and especially for synaptic structure and play key roles in the signal transduction responses to dopamine, serotonin, glutamate and acetyl choline. The unsaturated fatty acid components of phospholipids are abnormal in depression, with deficits of eicosapentaenoic acid and other omega-3 fatty acids and excesses of the omega-6 fatty acid arachidonic acid. Correction of this abnormality by treatment with eicosapentaenoic acid improves depression. The fatty acid abnormalities provide a rational explanation for the associations of depression with cardiovascular disease, immunological activation, cancer, diabetic complications and osteoporosis. The abnormalities cannot be explained by diet, although diet may attenuate or exacerbate their consequences. A number of enzyme abnormalities could explain the phenomena: phospholipase A(2), and coenzyme A-independent transacylase are strong candidates. Copyright 2001 John Wiley & Sons, Ltd.

Gene targets related to phospholipid and fatty acid metabolism in schizophrenia and other psychiatric disorders: an update

Phospholipids make up about 60% of the brain's dry weight and play key roles in many brain signal tranduction mechanisms. A recent review(1)identified the increasing evidence that abnormal phospholipid and related fatty acid metabolism may contribute to illnesses such as schizophrenia, bipolar disorder, depression and attention deficit hyperactivity disorder. This current paper reviews the main pathways of phospholipid metabolism, emphasizing the role of phospholipases of the A2 in signal tranduction processes. It also updates the chromosomal locations of regions likely to be involved in these disorders, and relates these to the known locations of genes directly or indirectly involved in phospholipid and fatty acid metabolism.

Muscle biopsy, macro EMG, and clinical characteristics in patients with schizophrenia

BACKGROUND

In a previous study of motor unit properties in patients with schizophrenia, muscle fiber histologic and electrophysiologic abnormalities were observed. The present study was designed to compare patients with schizophrenia with healthy control subjects with regard to muscle fiber histology and motor unit function. A second objective was to relate these variables to clinical characteristics.

METHODS

Twelve patients with first-episode schizophrenia and fifteen patients with chronic schizophrenia (DSM-III-R) and 27 matched control subjects were included in the study. Muscle biopsies were performed either in m. tibialis anterior or m. vastus lateralis. Electromyographic recordings (macro EMG) were made from the m. tibialis anterior motor units. Psychiatric ratings included the PANSS and extrapyramidal side effects.

RESULTS

Seven of the muscle biopsy specimens from the patients and one from the control subjects were classified as abnormal (p =.049). The most frequent abnormality was atrophic muscle fibers. Eight patients and no control subjects exhibited pathological macro EMG (p =.032). The findings were present in chronic as well as in first-episode patients with schizophrenia.

CONCLUSIONS

In approximately 50% of the patients, neuromuscular abnormalities were found either in the muscle biopsy or the macro EMG investigations. The results indicate that either a common pathologic process or different pathological processes are at hand in the neuromuscular system in patients with schizophrenia. The findings are compatible with a disturbed cell membrane function.

Nutritional (n-3) polyunsaturated fatty acids influence the behavioral responses to positive events in mice

The effect of (n-3) polyunsaturated fatty acid (PUFA) diet deficiency on behavioural responses to appetitive events was assessed in OF1 mice. Pups fed the same diet (deficient in alpha-linolenic acid or a standard control diet) as their dams were used aged 7 to 11 weeks. In a free choice model, the preference for a sucrose solution in both males and females was significantly lower in deficient than in control mice. Morphine conditioned place preference was obtained with the two diets at 8 and 16 mg/kg morphine, but the lower dose of 4 mg/kg induced a place preference in control but not in (n-3) deficient mice. Taken together, these results suggest that a nutritional (n-3) PUFA deficiency can alter the responsiveness to appetitive events.

Red cell and plasma fatty acid changes accompanying symptom remission in a patient with schizophrenia treated with eicosapentaenoic acid

The administration of the omega-3 fatty acid eicosapentaenoic acid (EPA) to a drug-naïve patient with schizophrenia, untreated with conventional antipsychotic medication, led to a dramatic and sustained clinical improvement in both positive and negative symptoms. This was accompanied by a correction in erythrocyte membranes of abnormalities in both n-3 and n-6 highly unsaturated fatty acids (HUFAs). Therefore EPA is able to reverse the phospholipid abnormalities previously described in schizophrenia. This reversal is associated with, and is likely to be the cause of, the clinical improvement. In particular, EPA appears to have reversed the depletion of not only n-3 HUFAs, but also of membrane arachidonic acid, possibly via inhibition of HUFA-specific phospholipase A(2), an enzyme which removes HUFAs from the S(N)2 position of membrane phospholipids, or by activation of a fatty acid coenzyme A ligase. Correction by EPA of abnormalities in both enzyme systems is not ruled out.

A continuum approach to modelling cognitive disorders

At the present time, the dominant conceptual framework in neuroscience views neurons as discrete information processing units. While this framework has undoubtedly been successful in explaining phenomena at the single-cell level, it has had less success in explaining large-scale neural phenomena such as cognitive disorders. An alternative conceptualization of brain function is in terms of an energy continuum, where energy is an abstract variable modelling the flow of electrochemical activity between neurons. Using this energy (E) model, large-scale phenomena may be incorporated within a single conceptual framework. This framework can in turn be related to the underlying biochemistry. The E model also generates testable predictions, and should prove quantifiable using differential equations. These claims are illustrated with simple examples from the spectrum of cognitive disorders.

Essential fatty acids, lipid membrane abnormalities, and the diagnosis and treatment of schizophrenia

Recent research suggests that deficient uptake or excessive breakdown of membrane phospholipids may be associated with schizophrenia. We review available clinical research on abnormalities in membrane fatty acid composition and metabolism in schizophrenia, and therapeutic trials of fatty acid in this disorder. All potentially relevant English-language articles were identified from the medical and psychiatric literature with the aid of computer searches using key words such as lipids, phospholipids, prostaglandins and schizophrenia. All studies which include human subjects are reviewed. Empirical studies related to membrane hypotheses of schizophrenia focus on: 1) assessment of prostaglandins (PG) and their essential fatty acid (EFA) precursors in the tissues of patients with schizophrenia; 2) evaluation of the niacin flush test as a possible diagnostic marker; 3) evaluation of phospholipase enzyme activity; 4) NMR spectroscopy studies of brain phospholipid metabolism; and 5) therapeutic trials of PG precursors for the treatment of schizophrenia. The most consistent clinical findings include red blood cell fatty acid membrane abnormalities, NMR spectroscopy evidence of increased phospholipid turnover and a therapeutic effect of omega-3 fatty acid supplementation of neuroleptic treatment in some schizophrenia patients. Studies of EFA metabolism have proved fruitful for generating and testing novel etiologic hypotheses and new therapeutic agents for schizophrenia. Greater attention to factors that influence tissue EFA levels such as diet, tobacco and alcohol are required to reconcile inconsistent findings. Treatment studies, although promising, require independent replication.