Membrane fatty acid levels as a predictor of treatment response in chronic schizophrenia

Differential impact of intermittent versus continuous treatment with clozapine on fatty acid metabolism in the brain of an MK-801-induced mouse model of schizophrenia

Continuous antipsychotic treatment is often recommended to prevent relapse in schizophrenia. However, the efficacy of antipsychotic treatment appears to diminish in patients with relapsed schizophrenia and the underlying mechanisms are still unknown. Moreover, though the findings are inconclusive, several recent studies suggest that intermittent versus continuous treatment may not significantly differ in recurrence risk and therapeutic efficacy but potentially reduce the drug dose and side effects. Notably, disturbances in fatty acid (FA) metabolism are linked to the onset/relapse of schizophrenia, and patients with multi-episode schizophrenia have been reported to have reduced FA biosynthesis. We thus utilized an MK-801-induced animal model of schizophrenia to evaluate whether two treatment strategies of clozapine would affect drug response and FA metabolism differently in the brain. Schizophrenia-related behaviors were assessed through open field test (OFT) and prepulse inhibition (PPI) test, and FA profiles of prefrontal cortex (PFC) and hippocampus were analyzed by gas chromatography-mass spectrometry. Additionally, we measured gene expression levels of enzymes involved in FA synthesis. Both intermittent and continuous clozapine treatment reversed hypermotion and deficits in PPI in mice. Continuous treatment decreased total polyunsaturated fatty acids (PUFAs), saturated fatty acids (SFAs) and FAs in the PFC, whereas the intermittent administration increased n-6 PUFAs, SFAs and FAs compared to continuous administration. Meanwhile, continuous treatment reduced the expression of Fads1 and Elovl2, while intermittent treatment significantly upregulated them. This study discloses the novel findings that there was no significant difference in clozapine efficacy between continuous and intermittent administration, but intermittent treatment showed certain protective effects on phospholipid metabolism in the PFC.

Nutraceuticals in Psychiatric Disorders: A Systematic Review

Correct nutrition and diet are directly correlated with mental health, functions of the immune system, and gut microbiota composition. Diets with a high content of some nutrients, such as fibers, phytochemicals, and short-chain fatty acids (omega-3 fatty acids), seem to have an anti-inflammatory and protective action on the nervous system. Among nutraceuticals, supplementation of probiotics and omega-3 fatty acids plays a role in improving symptoms of several mental disorders. In this review, we collect data on the efficacy of nutraceuticals in patients with schizophrenia, autism spectrum disorders, major depression, bipolar disorder, and personality disorders. This narrative review aims to provide an overview of recent evidence obtained on this topic, pointing out the direction for future research.

An association between PPARα-L162V polymorphism and increased plasma LDL cholesterol levels after risperidone treatment

Peroxisome proliferator-activated receptor alpha (PPARα) and antipsychotic medications both influence polyunsaturated fatty acids (PUFA) homeostasis, and thus PPARα polymorphism may be linked to antipsychotic treatment response. Here we investigated whether the functional leucine 162 valine (L162V) polymorphism in PPARα influenced antipsychotic treatment in a group of psychosis patients (N = 186), as well as in a patient subgroup with risperidone, paliperidone, or combination treatment (N = 65). Antipsychotic-naïve first-episode patients and nonadherent chronic individuals were genotyped by polymerase chain reaction analysis. At baseline, and after 8 weeks of treatment with various antipsychotic medications, we assessed the patients' Positive and Negative Syndrome Scale (PANSS) scores; PANSS factors; and metabolic syndrome-related parameters, including fasting plasma lipid and glucose levels, and body mass index. In the total patient group, PPARα polymorphism did not affect PANSS psychopathology or metabolic parameters. However, in the subgroup of patients with risperidone, paliperidone, or combination treatment, PPARα polymorphism influenced changes in plasma LDL cholesterol. Specifically, compared to PPARα-L162L homozygous patients, PPARα-L162V heterozygous individuals exhibited significantly higher increases of LDL cholesterol levels after antipsychotic treatment. The PPARα polymorphism had a strong effect size, but a relatively weak contribution to LDL cholesterol level variations (∼12.8 %).

Correlations between omega-3 fatty acids and inflammatory/glial abnormalities: the involvement of the membrane and neurotransmitter dysfunction in schizophrenia

Introduction

Macrophages or T-lymphocytes triggered inflammation and, consequently, activated glial cells may contribute to neuroinflammation and neurotransmitter dysfunction in schizophrenia (SZ), while omega(n)-3 polyunsaturated fatty acids (PUFAs) can attenuate some SZ symptoms through anti-inflammatory effects. However, the correlations between macrophage/T-lymphocyte-produced cytokines and glia phenotypes, between inflammatory status and PUFAs composition, between cytokines and neurotransmitter function, and between n-3 PUFAs and neurotransmitter abnormality in SZ are unclear.

Methods

Changes in T-helper (h) patterns, peripheral macrophage/glial markers, PUFAs profile, membrane fluidity, and neurotransmitter functions were evaluated in SZ patients (n = 50) and healthy controls (n = 30) using ELISA, gas chromatography, fluorescence anisotropy techniques, and HPLC, respectively.

Results

Compared to the control, blood lymphocyte proliferation, the concentration of macrophage/microglia phenotype M1 markers, including cytokines IL-1β, TNF-α (Th1) and IL-6 (Th2), and astrocyte phenotype A1 marker S100β was significantly increased, while IL-17 and n-3 PUFAs contents, n-3/n-6 ratio, and membrane fluidity (FLU) were significantly decreased in SZ. Moreover, increased DA and HVA, decreased 5-HT and NE, and their metabolites appeared in SZ. Moreover, negative correlations between IL-6 and A2 marker Brain-Derived Neurotrophic Factor (BDNF) or n-3 PUFAs EPA and between IL-1β and FLU or 5HIAA, while positive correlations between EPA and 5-HIAA and between FLU and DHA were found in SZ.

Discussion

These findings showed (1) no clear Th pattern, but pro-inflammatory-dominant immunity occurred; (2) the pro-inflammatory pattern may result in the activated microglia M1 and astrocyte A1 phenotype; and (3) increased pro-inflammatory cytokines were related to decreased n-3 PUFA and decreased membrane fluidity and dysfunctional neurotransmitter systems in SZ.

Analysis of polyunsaturated fatty acids in antipsychotic-free individuals with at-risk mental state and patients with first-episode schizophrenia

Introduction

Abnormalities in membrane phospholipids are considered one of the pathophysiological backgrounds for schizophrenia. This study, explores the fatty acid composition of erythrocyte membranes and its association with clinical characteristics in two groups: individuals with an at-risk mental state (ARMS) and patients experiencing their first-episode of schizophrenia (FES).

Materials and methods

This study measured erythrocyte membrane fatty acids in 72 antipsychotic-free individuals with ARMS, 18 antipsychotic-free patients with FES, and 39 healthy volunteers. Clinical symptoms and cognitive and social functions were assessed using the Positive and Negative Syndrome Scale (PANSS), Brief Assessment of Cognition in Schizophrenia (BACS), Schizophrenia Cognition Rating Scale (SCoRS), and Social and Occupational Functioning Assessment Scale (SOFAS).

Results

Eicosapentaenoic and docosapentaenoic acid levels were lower in the ARMS and FES groups than in the healthy control group. In contrast, nervonic acid (NA) levels were markedly higher in the ARMS and FES groups than in the controls, while only the FES group showed higher levels of arachidonic acid. Oleic acid and NA levels were significantly associated with PANSS scores in both the FES and ARMS groups, particularly for the negative and general subscores. However, the patient groups had no significant associations between the fatty acid composition and the BACS, SCoRS, and SOFAS scores. Furthermore, the baseline fatty acid composition did not differ between the ARMS individuals who later developed psychosis (N = 6) and those who were followed for more than 2 years without developing psychosis onset (N = 30).

Discussion

The findings suggest that abnormal fatty acid compositions may be shared in the early stages of schizophrenia and the clinical high-risk state for psychosis and may serve as vulnerability markers of psychopathology.

Association between PLA2 gene polymorphisms and treatment response to antipsychotic medications: A study of antipsychotic-naïve first-episode psychosis patients and nonadherent chronic psychosis patients

Here we investigated whether antipsychotic treatment was influenced by three polymorphisms: rs10798059 (BanI) in the phospholipase A2 (PLA2)G4A gene, rs4375 in PLA2G6, and rs1549637 in PLA2G4C. A total of 186 antipsychotic-naïve first-episode psychosis patients or nonadherent chronic psychosis individuals (99 males and 87 females) were genotyped by polymerase chain reaction analysis/restriction fragment length polymorphism. At baseline, and after 8 weeks of treatment with various antipsychotic medications, we assessed patients' Positive and Negative Syndrome Scale (PANSS) scores, PANSS factors, and metabolic syndrome-related parameters (fasting plasma lipid and glucose levels, and body mass index). We found that PLA2G4A polymorphism influenced changes in PANSS psychopathology, and PLA2G6 polymorphism influenced changes in PANSS psychopathology and metabolic parameters. PLA2G4C polymorphism did not show any impact on PANSS psychopathology or metabolic parameters. The polymorphisms' effect sizes were estimated as moderate to strong, with contributions ranging from around 6.2-15.7%. Furthermore, the polymorphisms' effects manifested in a gender-specific manner.

Higher stress response and altered quality of life in schizophrenia patients with low membrane levels of docosahexaenoic acid

Schizophrenia is a severe, chronic, and heterogeneous mental disorder that affects approximately 1% of the world population. Ongoing research aims at clustering schizophrenia heterogeneity into various "biotypes" to identify subgroups of individuals displaying homogeneous symptoms, etiopathogenesis, prognosis, and treatment response. The present study is in line with this approach and focuses on a biotype partly characterized by a specific membrane lipid composition. We have examined clinical and biological data of patients with stabilized schizophrenia, including the fatty acid content of their erythrocyte membranes, in particular the omega-3 docosahexaenoic acid (DHA). Two groups of patients of similar size were identified: the DHA- group (N = 19) with a lower proportion of membrane DHA as compared to the norm in the general population, and the DHAn group (N = 18) with a normal proportion of DHA. Compared to DHAn, DHA- patients had a higher number of hospitalizations and a lower quality of life in terms of perceived health and physical health. They also exhibited significant higher interleukin-6 and cortisol blood levels. These results emphasize the importance of measuring membrane lipid and immunoinflammatory biomarkers in stabilized patients to identify a specific subgroup and optimize non-pharmacological interventions. It could also guide future research aimed at proposing specific pharmacological treatments.

Reduced erythrocyte membrane polyunsaturated fatty acid levels indicate diminished treatment response in patients with multi- versus first-episode schizophrenia

Antipsychotic effects seem to decrease in relapsed schizophrenia patients and the underlying mechanisms remain to be elucidated. Based on the essential role of polyunsaturated fatty acids in brain function and the treatment of schizophrenia, we hypothesize that disordered fatty acid metabolism may contribute to treatment resistance in multi-episode patients. We analyzed the erythrocyte membrane fatty acids in 327 schizophrenia patients under various episodes (numbers of patients: first-episode drug naïve 89; 2–3 episodes 110; 4–6 episodes 80; over 6 episodes 48) and 159 age- and gender-matched healthy controls. Membrane fatty acid levels and PANSS scales were assessed at baseline of antipsychotic-free period and one-month of follow-up after treatment. Totally, both saturated and unsaturated fatty acids were reduced at baseline when compared to healthy controls. Subgroup analyses among different episodes indicated that in response to atypical antipsychotic treatment, the membrane fatty acids were only increased in patients within 3 episodes, and this therapeutic effects on omega-3 index were merely present in the first episode. Results of fatty acid ratios suggested that dysregulations of enzymes such as D6 desaturase, D5 desaturase, and elongases for polyunsaturated fatty acids in patients with multi-episode schizophrenia could account for the differences. Additionally, certain fatty acid level/ratio changes were positively correlated with symptom improvement. The alterations of C22:5n3 and omega-3 index, gender, and the number of episodes were significant risk factors correlated with treatment responsiveness. Using targeted metabolomic approach, we revealed the potential mechanisms underlying abnormal fatty acid metabolism responsible for reduced treatment response in patients with multi-episode schizophrenia.

Polyunsaturated Fatty Acids: What is Their Role in Treatment of Psychiatric Disorders?

In the central nervous system omega-3 fatty acids modulate cell signaling and affect dopaminergic and serotonergic pathways. On this basis, a new application for omega-3 fatty acids has been proposed, concerning the treatment of several psychiatric disorders. The present article is an update of a previous systematic review and is aimed to provide a complete report of data published in the period between 1980 and 2019 on efficacy and tolerability of omega-3 fatty acids in psychiatric disorders. In July 2019, an electronic search on PUBMED, Medline and PsychINFO of all RCTs, systematic reviews and meta-analyses on omega-3 fatty acids and psychiatric disorders without any filter or MESH restriction was performed. After eligibility processes, the final number of records included in this review was 126. One hundred and two of these studies were RCTs, while 24 were reviews and meta-analyses. The role of omega-3 fatty acids was studied in schizophrenia, major depression, bipolar disorder, anxiety disorders, obsessive-compulsive disorder, post-traumatic stress disorder, attention deficit hyperactivity disorder (ADHD), autism spectrum disorders, eating disorders, substance use disorder and borderline personality disorder. The main evidence of the efficacy of omega-3 fatty acids has been obtained in treating depressive symptoms in patients with major depression and, to a lesser degree, bipolar depression. Some efficacy was also found in early phases of schizophrenia in addition to antipsychotic treatment, but not in the chronic phases of psychosis. Small beneficial effects of omega-3 fatty acids were observed in ADHD and positive results were reported in a few trials on core symptoms of borderline personality disorder. For other psychiatric disorders results are inconsistent.

Docosahexaenoic acid (DHA): An essential nutrient and a nutraceutical for brain health and diseases

Docosahexaenoic acid (DHA), a polyunsaturated fatty acid (PUFA) enriched in phospholipids in the brain and retina, is known to play multi-functional roles in brain health and diseases. While arachidonic acid (AA) is released from membrane phospholipids by cytosolic phospholipase A2 (cPLA2), DHA is linked to action of the Ca2+-independent iPLA2. DHA undergoes enzymatic conversion by 15-lipoxygenase (Alox 15) to form oxylipins including resolvins and neuroprotectins, which are powerful lipid mediators. DHA can also undergo non-enzymatic conversion by reacting with oxygen free radicals (ROS), which cause the production of 4-hydoxyhexenal (4-HHE), an aldehyde derivative which can form adducts with DNA, proteins and lipids. In studies with both animal models and humans, there is evidence that inadequate intake of maternal n-3 PUFA may lead to aberrant development and function of the central nervous system (CNS). What is less certain is whether consumption of n-3 PUFA is important in maintaining brain health throughout one's life span. Evidence mostly from non-human studies suggests that DHA intake above normal nutritional requirements might modify the risk/course of a number of diseases of the brain. This concept has fueled much of the present interest in DHA research, in particular, in attempts to delineate mechanisms whereby DHA may serve as a nutraceutical and confer neuroprotective effects. Current studies have revealed ability for the oxylipins to regulation of cell redox homeostasis through the Nuclear factor (erythroid-derived 2)-like 2/Antioxidant response element (Nrf2/ARE) anti-oxidant pathway, and impact signaling pathways associated with neurotransmitters, and modulation of neuronal functions involving brain-derived neurotropic factor (BDNF). This review is aimed at describing recent studies elaborating these mechanisms with special regard to aging and Alzheimer's disease, autism spectrum disorder, schizophrenia, traumatic brain injury, and stroke.

Omega – 3 fatty acids in schizophrenia – part I: importance in the pathophysiology of schizophrenia

Despite the increasing offer of antipsychotic drugs, the effectiveness of pharmacotherapy in schizophrenia is still unsatisfactory. Drug resistance, lack of complete remission and the increasing risk of metabolic complications are the reasons why the new forms of therapy in schizophrenia among which unsaturated essential fatty acids omega 3 (EFAs ω-3) affecting the proper functioning of nervous system, are mentioned, are being looked for.

Fatty acids represent 50-60% of the dry weight of the brain and diet is one of the factors that influence the value of each of the fat fractions in the neuron membranes. Patients with schizophrenia tend to have irregular nutritional status concerning essential fatty acids ω-3, which might result from metabolic disorders or irregular consumption of fatty acids.

Apart from being a review of the literature on this subject, this very paper characterizes essential fatty acids ω-3, their metabolism, the most important sources in the diet and the opinions of experts in the field about the recommended intake. It pays attention to the role of essential fatty acids in both the structure and functioning of the central nervous system is, as well as their role in the pathophysiology of schizophrenia, with particular emphasis on the membrane concept by David Horrobin. The assessment of the errors in consumption and metabolism of essential fatty acids are described as well.

The evidence was found both in epidemiological and modeling studies. It supports the participation of EFAs in etiopathogenesis and pathophysiology of schizophrenia. Further research is needed, both observational and interventional, as to the role of essential fatty acids ω-3 in the functioning of the CNS as well as the development and course of schizophrenia.

Lipid profiles in schizophrenia associated with clinical traits: a five year follow-up study

BACKGROUND

Alterations in serum and membrane lipids may be involved in schizophrenia pathophysiology. It is not known whether lipid profiles are associated with disease severity or current symptom level.

METHODS

Clinical and lipid data were gathered from 55 patients with schizophrenia admitted to psychiatric emergency wards in an acute stage of the disease (T1). The patients were re-examined after 5 years at a stable phase (T2). The clinical assessments included Positive and Negative Syndrome Scale (PANSS total, positive, negative) and Global Assessment of Functioning (GAF S, symptom and F, function). Serum lipids (cholesterol and triglyceride) and membrane polyunsaturated fatty acids (PUFA, LCPUFA) were measured. Healthy controls were recruited among hospital workers.

RESULTS

Serum triglyceride was significantly higher in patients with schizophrenia compared to healthy controls both at T1 and T2 (p < 0.001), while serum cholesterol did not differ significantly. The levels of serum lipids in patients remained stable over time. At T1, serum lipids and symptoms were not significantly correlated. At T2, higher serum lipids were associated with more severe symptoms and poorer functioning. Higher serum lipid levels at T1 were associated with more severe symptoms and poorer functioning at T2; cholesterol with GAF-S (p < 0.05), triglyceride with PANSS total (p < 0.05), GAF-S (p < 0.01) and GAF-F (p < 0.01). Membrane lipids were significantly lower in the patient group compared to healthy controls at T1 (PUFA p < 0.001, LCPUFA p < 0.001), but not at T2. Membrane lipids were not significantly correlated with symptoms at T1, but significantly associated with negative symptoms and functioning at T2 as previously reported.

CONCLUSIONS

The present findings suggest different roles of membrane and serum lipids in schizophrenia pathophysiology. To further elucidate the relation of lipid biology to disease traits, replication in independent studies of longitudinal samples are warranted.

Association between serum lipids and membrane fatty acids and clinical characteristics in patients with schizophrenia

OBJECTIVE

Earlier reports indicate that patients with schizophrenia have altered lipid levels in serum and cell membranes. The purpose of this study was to determine the relationship between clinical characteristics and serum and membrane lipids.

METHOD

Fifty-five patients with schizophrenia and 51 healthy controls were included. The patients were characterized with Positive and Negative Syndrome Scale (PANSS) and Global Assessment of Functioning (GAF). Serum lipids [high- and low-density lipoprotein cholesterol (HDL, LDL) and triglyceride (TG)] and erythrocyte polyunsaturated fatty acids (PUFA) were measured.

RESULTS

Among the participants with schizophrenia, there was a significant correlation between serum triglyceride levels and PANSS-positive symptoms (r = 0.28, P = 0.04), GAF-S (r = -0.48, P = 0.001) and GAF-F (r = -0.32, P = 0.01), and between HDL level and GAF-S (r = 0.37, P = 0.008) and GAF-F (r = 0.28, P = 0.04). Long-chain PUFA were significantly associated with PANSS-negative symptoms (r = 0.52, P < 0.001), GAF-S (r = -0.32, P = 0.02), and GAF-F (r = -0.29, P = 0.04). The patients with schizophrenia had significantly higher TG (P < 0.001) and lower HDL (P < 0.001) levels than healthy controls. HDL was also lower in the subgroup (n = 11) not receiving antipsychotic medication (P = 0.02).

CONCLUSION

The results suggest associations between lipid profile and clinical characteristics. This may indicate a role for lipid biology in schizophrenia pathophysiology.

Determination of sex-based differences in serum γ-linolenic [corrected] acid and dihomo-γ-linolenic [corrected] acid using gas chromatography-mass spectrometry

Because serum unsaturated fatty acids can provide useful information on disease diagnosis, the simultaneous determination of several fatty acids in small volumes of human serum would be beneficial for clinical applications. In the present study, serum fatty acids were extracted with n-heptane/chloroform from 10μL of serum collected from 26 healthy Japanese subjects (11 men, ages 23-37 years; 15 women, ages 18-37 years) after deproteinization with perchloric acid, derivatization to their methyl ester using p-toluenesulfonic acid as an acid catalyst, and subsequent separation and measurement by gas chromatography-mass spectrometry (GC-MS) in the selected ion monitoring mode. Nine types of fatty acids (palmitoleic acid [PLA], oleic acid [OA], linoleic [corrected] acid [LA], γ-linolenic acid [GLA], α-linolenic acid [ALA], dihomo-GLA [DGLA], arachidonic acid [AA], eicosapentaenoic acid [EPA], and docosahexaenoic acid [DHA]) were analyzed in the serum within 35 min by GC-MS. The concentrations of these fatty acids in serum ranged from 3.64±0.38μM (GLA) to 413±26.3 μM (LA). Among these nine fatty acids, GLA and DGLA levels were significantly lower in women than in men (p=0.0034 and 0.0012, respectively), suggesting that there may be sex-based differences in the biosynthetic production or metabolic processes of GLA and DGLA in humans.

Lipidomics reveals early metabolic changes in subjects with schizophrenia: effects of atypical antipsychotics

There is a critical need for mapping early metabolic changes in schizophrenia to capture failures in regulation of biochemical pathways and networks. This information could provide valuable insights about disease mechanisms, trajectory of disease progression, and diagnostic biomarkers. We used a lipidomics platform to measure individual lipid species in 20 drug-naïve patients with a first episode of schizophrenia (FE group), 20 patients with chronic schizophrenia that had not adhered to prescribed medications (RE group), and 29 race-matched control subjects without schizophrenia. Lipid metabolic profiles were evaluated and compared between study groups and within groups before and after treatment with atypical antipsychotics, risperidone and aripiprazole. Finally, we mapped lipid profiles to n3 and n6 fatty acid synthesis pathways to elucidate which enzymes might be affected by disease and treatment. Compared to controls, the FE group showed significant down-regulation of several n3 polyunsaturated fatty acids (PUFAs), including 20:5n3, 22:5n3, and 22:6n3 within the phosphatidylcholine and phosphatidylethanolamine lipid classes. Differences between FE and controls were only observed in the n3 class PUFAs; no differences where noted in n6 class PUFAs. The RE group was not significantly different from controls, although some compositional differences within PUFAs were noted. Drug treatment was able to correct the aberrant PUFA levels noted in FE patients, but changes in re patients were not corrective. Treatment caused increases in both n3 and n6 class lipids. These results supported the hypothesis that phospholipid n3 fatty acid deficits are present early in the course of schizophrenia and tend not to persist throughout its course. These changes in lipid metabolism could indicate a metabolic vulnerability in patients with schizophrenia that occurs early in development of the disease.

The Role of Essential Fatty Acids in Human Health

Fatty acid research began about 90 years ago but intensified in recent years. Essential fatty acids (linoleic and α-linolenic) must come from diet. Other fatty acids may come from diet or may be synthesized. Fatty acids are major components of cell membrane structure, modulate gene transcription, function as cytokine precursors, and serve as energy sources in complex, interconnected systems. It is increasingly apparent that dietary fatty acids influence these vital functions and affect human health. While the strongest evidence for influence is found in cardiovascular disease and mental health, many additional conditions are affected. Problematic changes in the fatty acid composition of human diet have also taken place over the last century. This review summarizes current understanding of the pervasive roles of essential fatty acids and their metabolites in human health.

A meta-analysis of the polyunsaturated fatty acid composition of erythrocyte membranes in schizophrenia

BACKGROUND

Membrane abnormalities in polyunsaturated fatty acids (PUFAs) have been reported in schizophrenia and have been associated with brain tissue loss in normal ageing. Therefore PUFA may be involved in the excessive brain tissue loss reported in schizophrenia.

METHODS

A systematic MEDLINE database search was conducted to identify studies that compared PUFAs in erythrocyte membranes in patients and controls. Patients were categorized by medication regime in medication naive first-episode patients, and patients receiving typical or atypical antipsychotics.

SAMPLE

Fourteen studies were included, comprising a total of 429 patients with schizophrenia and 444 healthy control subjects. Cohen's d effect sizes were calculated for PUFAs in erythrocyte membranes using the random-effects model. Combined Cohen's d was calculated separately for patients on different medication regime.

RESULTS

Medication-naive patients and patients taking typical antipsychotics showed significantly (p<0.01) decreased concentrations of arachidonic (AA), docosahexaenoic (DHA), and docosapentaenoic (DPA) acid. In addition, patients taking typical antipsychotics showed decreased linoleic (LA), dihomo-γ-linolenic acid (DGLA), eicosapentaenoic (EPA) and docosatetraenoic (DTA) acid (p<0.01). Patients taking atypical antipsychotics showed decreased DHA (p<0.01) only.

CONCLUSIONS

PUFA concentrations in erythrocyte membranes are decreased in schizophrenia. Of particular importance in patients are lower concentrations of DHA and AA, two fatty acids that are abundant in the brain and important precursors in the cell-signalling cascade.

Impaired plasmalogens in patients with schizophrenia

Plasmalogens are a subclass of glycerophospholipids and ubiquitous constituents of cellular membranes and serum lipoproteins. Several neurological disorders show decreased level of plasmogens. An earlier study found differences in plasma phospholipids between unmedicated patients with schizophrenia and matched healthy control subjects. We here report a comparison of plasma plasmalogen levels across 20 drug-naïve patients experiencing first psychotic episodes, 20 recently unmedicated patients experiencing psychotic relapses after failing to comply with prescribed medications, and 17 matched healthy control subjects. Multiple plasma phosphatidylcholine and phosphatidylethanolamine plasmalogen levels were significantly lower in first episode patients and patients with recurrent disease compared to healthy controls. Reduced plasmalogen levels appear to be a trait evident at the onset of psychotic illness and after multiple psychotic relapses. It is implied that reductions in plasmalogen levels are not related to antipsychotic treatment but due to the illness itself. Reduced plasmalogen levels suggest impairments in membrane structure and function in patients with schizophrenia that might happen early in development. This may serve as a clue to the neurobiology of schizophrenia and should be studied as a potential biomarker for individuals at risk for schizophrenia.

A structure-function mechanism for schizophrenia

THE MULTIPLE ETIOLOGIES OF SCHIZOPHRENIA PROMPT US TO RAISE THE QUESTION: what final common pathway can induce a convincing sense of the reality of the hallucinations in this disease? The observation that artificial stimulation of an intermediate order of neurons of a normal nervous system induces hallucinations indicates that the lateral entry of activity (not resulting from canonical synaptic transmission) at intermediate neuronal orders may provide a mechanism for hallucinations. Meaningful hallucinations can be de-constructed into an organized temporal sequence of internal sensations of associatively learned items that occur in the absence of any external stimuli. We hypothesize that these hallucinations are autonomously generated by the re-activation of pathological non-specific functional LINKs formed between the postsynaptic membranes at certain neuronal orders and are examined as a final common mechanism capable of explaining most of the features of the disease. Reversible and stabilizable hemi-fusion between simultaneously activated adjacent postsynaptic membranes is viewed as one of the normal mechanisms for functional LINK formation and is dependent on lipid membrane composition. Methods of removing the proteins that may traverse the non-specifically hemi-fused membrane segments and attempts to replace the phospholipid side chains to convert the membrane composition to a near-normal state may offer therapeutic opportunities.