Fatty acids and schizophrenia

Attenuated niacin response is associated with a subtype of first-episode drug-naïve psychosis characterized as serious negative symptoms

Although the phenomenon of attenuated niacin response (ANR) has been widely replicated in some patients with first-episode psychosis (FEP), its relevance to the negative symptoms (NS) of psychosis remains unclear. Total of 240 patients with drug-naïve FEP and 101 healthy controls (HCs) were recruited, and 209 were followed up for 1 year. Psychotic symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS), and niacin-induced responses were measured using laser Doppler flowmetry. We calculated the log-transform EC50 [concentration of methyl nicotinate required to elicit a half-maximal blood flow (MBF) response] and MBF values. Core-NS was generated by factor analysis of the PANSS-NS subscale and cluster analysis to produce subtypes. Significant differences were found in the log10 (EC50) values between the FEP and HC groups (p < 0.001), supporting the ANR in patients with FEP. A higher NS severity was found in the ANR subgroup than that in other patients. Factor analysis determined that a two-dimensional model included core NS and rigidity of thinking. The log10 (EC50) value was significantly associated with only the core NS. Cluster analysis revealed three subtypes-36.7% (cluster-1, n = 88), 16.7% (cluster-2, n = 40), and 46.7% (cluster-3, n = 112). Cluster-2 characterized by extensive NS appeared to have a more remarkable ANR and less symptomatic improvement than those with other clusters during follow-up. No significant changes were found in the niacin response trajectories between the baseline and follow-up. Our findings indicate a significant correlation between ANR and core NS in patients with FEP. ANR may be a potential biomarker for certain subtypes with NS-dominated characteristics and poor symptomatic remission.

Replication of the abnormal niacin response in first episode psychosis measured using laser Doppler flowmeter

INTRODUCTION

Impaired sensitivity of the skin flush response to niacin is found in approximately 30% of patients with schizophrenia. Although the niacin response abnormality (NRA) may serve as a useful endophenotype for schizophrenia, few studies have directly replicated NRA in patients with first-episode psychosis (FEP).

METHODS

In total, 204 patients with FEP, 16 with psychotic mood disorder (PMD), and 68 healthy controls (HC) were included. The log₁₀ (EC₅₀ ) values represent the concentration of methyl nicotinate required to elicit a half-maximal blood flow (MBF) response, and the MBF value was calculated. The NRA was defined as having log₁₀ (EC₅₀ ) molar value above the 90% and an MBF value below the 60% of those in the HC group.

RESULTS

In total, 13.7% of the FEP, 12.5% of the PMD, and 7.4% of the HC group met the definition of NRA. Significant differences were found in the log₁₀ (EC₅₀ ) values between the FEP and HC groups (p = .014) and in the MBF between the FEP and PMD groups (p = .011). Patients with FEP and NRA had more severe negative symptoms than those with a normal niacin response.

DISCUSSION

These data represent the NRA in patients with FEP, defining a small subgroup of patients with early-phase psychosis possessing a clinically significant phospholipid-signaling defect.

Attenuated niacin-induced skin flush response in individuals with clinical high risk for psychosis

Background

Impaired sensitivity of the skin flush response to niacin is one of the most replicated findings in patients with schizophrenia. However, prior studies have usually focused on postonset psychosis, and little is known about the clinical high-risk (CHR) phase of niacin sensitivity in psychosis.

Aims

To profile and compare the niacin flush response among CHR individuals (converters and non-converters), patients with first-episode schizophrenia (FES) and healthy controls (HCs).

Methods

Sensitivity to four concentrations (0.1-0.0001 M) of aqueous methylnicotinate was tested in 105 CHR individuals, 57 patients with FES and 52 HCs. CHR individuals were further grouped as converters and non-converters according to the 2-year follow-up outcomes. Skin flush response scores were rated on a 4-point scale.

Results

Of the 105 CHR individuals, 21 individuals were lost during the study, leaving 84 CHR individuals; 16 (19.0%) converted to full psychosis at 2 years of follow-up. Flush response scores identified in the CHR samples were characterised as modest degree levels, intermediate between those of HC individuals and patients with FES. The flush responses in the CHR group mimicked the responses observed in the FES group at higher concentrations (0.01 M, 0.1 M) and longer time points (15 min, 20 min); however, these became comparable with the responses in the HC group at the shorter time points and at lower concentrations. The converters exhibited lower mean flush response scores than the non-converters.

Conclusions

Attenuated niacin-induced flushing emerged during the early phase of psychosis. New devices should be developed and verified for objective quantification of skin responses in the CHR population.

Apolipoprotein D

ApoD is a 25 to 30 kDa glycosylated protein, member of the lipocalin superfamily. As a transporter of several small hydrophobic molecules, its known biological functions are mostly associated to lipid metabolism and neuroprotection. ApoD is a multi-ligand, multi-function protein that is involved lipid trafficking, food intake, inflammation, antioxidative response and development and in different types of cancers. An important aspect of ApoD's role in lipid metabolism appears to involve the transport of arachidonic acid, and the modulation of eicosanoid production and delivery in metabolic tissues. ApoD expression in metabolic tissues has been associated positively and negatively with insulin sensitivity and glucose homeostasis in a tissue dependent manner. ApoD levels rise considerably in association with aging and neuropathologies such as Alzheimer's disease, stroke, meningoencephalitis, moto-neuron disease, multiple sclerosis, schizophrenia and Parkinson's disease. ApoD is also modulated in several animal models of nervous system injury/pathology.

Enhancing Omega-3 Long-Chain Polyunsaturated Fatty Acid Content of Dairy-Derived Foods for Human Consumption

Omega-3 polyunsaturated fatty acids (n-3 PUFA) are termed essential fatty acids because they cannot be synthesized de novo by humans due to the lack of delta-12 and delta-15 desaturase enzymes and must therefore be acquired from the diet. n-3 PUFA include α-linolenic acid (ALA, 18:3n-3), eicosapentaenoic (EPA, 20:5n-3), docosahexaenoic (DHA, 22:6n-3), and the less recognized docosapentaenoic acid (DPA, 22:5n-3). The three long-chain (≥C20) n-3 PUFA (n-3 LC-PUFA), EPA, DHA, and DPA play an important role in human health by reducing the risk of chronic diseases. Up to the present time, seafood, and in particular, fish oil-derived products, have been the richest sources of n-3 LC-PUFA. The human diet generally contains insufficient amounts of these essential FA due largely to the low consumption of seafood. This issue provides opportunities to enrich the content of n-3 PUFA in other common food groups. Milk and milk products have traditionally been a major component of human diets, but are also among some of the poorest sources of n-3 PUFA. Consideration of the high consumption of milk and its processed products worldwide and the human health benefits has led to a large number of studies targeting the enhancement of n-3 PUFA content in dairy products. The main objective of this review was to evaluate the major strategies that have been employed to enhance n-3 PUFA content in dairy products and to unravel potential knowledge gaps for further research on this topic. Nutritional manipulation to date has been the main approach for altering milk fatty acids (FA) in ruminants. However, the main challenge is ruminal biohydrogenation in which dietary PUFA are hydrogenated into monounsaturated FA and/or ultimately, saturated FA, due to rumen microbial activities. The inclusion of oil seed and vegetable oil in dairy animal diets significantly elevates ALA content, while the addition of rumen-protected marine-derived supplements is the most effective way to increase the concentration of EPA, DHA, and DPA in dairy products. In our view, the mechanisms of n-3 LC-PUFA biosynthesis pathway from ALA and the biohydrogenation of individual n-3 LC-PUFA in ruminants need to be better elucidated. Identified knowledge gaps regarding the activities of candidate genes regulating the concentrations of n-3 PUFA and the responses of ruminants to specific lipid supplementation regimes are also critical to a greater understanding of nutrition-genetics interactions driving lipid metabolism.

A genome-wide association study of red-blood cell fatty acids and ratios incorporating dietary covariates: Framingham Heart Study Offspring Cohort

Recent analyses have suggested a strong heritable component to circulating fatty acid (FA) levels; however, only a limited number of genes have been identified which associate with FA levels. In order to expand upon a previous genome wide association study done on participants in the Framingham Heart Study Offspring Cohort and FA levels, we used data from 2,400 of these individuals for whom red blood cell FA profiles, dietary information and genotypes are available, and then conducted a genome-wide evaluation of potential genetic variants associated with 22 FAs and 15 FA ratios, after adjusting for relevant dietary covariates. Our analysis found nine previously identified loci associated with FA levels (FADS, ELOVL2, PCOLCE2, LPCAT3, AGPAT4, NTAN1/PDXDC1, PKD2L1, HBS1L/MYB and RAB3GAP1/MCM6), while identifying four novel loci. The latter include an association between variants in CALN1 (Chromosome 7) and eicosapentaenoic acid (EPA), DHRS4L2 (Chromosome 14) and a FA ratio measuring delta-9-desaturase activity, as well as two loci associated with less well understood proteins. Thus, the inclusion of dietary covariates had a modest impact, helping to uncover four additional loci. While genome-wide association studies continue to uncover additional genes associated with circulating FA levels, much of the heritable risk is yet to be explained, suggesting the potential role of rare genetic variation, epistasis and gene-environment interactions on FA levels as well. Further studies are needed to continue to understand the complex genetic picture of FA metabolism and synthesis.

The Energy Metabolism Dysfunction in Psychiatric Disorders Postmortem Brains: Focus on Proteomic Evidence

Psychiatric disorders represent a great medical and social challenge and people suffering from these conditions face many impairments regarding personal and professional life. In addition, a mental disorder will manifest itself in approximately one quarter of the world's population at some period of their life. Dysfunction in energy metabolism is one of the most consistent scientific findings associated with these disorders. With this is mind, this review compiled data on disturbances in energy metabolism found by proteomic analyses of postmortem brains collected from patients affected by the most prevalent psychiatric disorders: schizophrenia (SCZ), bipolar disorder (BPD), and major depressive disorder (MDD). We searched in the PubMed database to gather the studies and compiled all the differentially expressed proteins reported in each work. SCZ studies revealed 92 differentially expressed proteins related to energy metabolism, while 95 proteins were discovered in BPD, and 41 proteins in MDD. With the compiled data, it was possible to determine which proteins related to energy metabolism were found to be altered in all the disorders as well as which ones were altered exclusively in one of them. In conclusion, the information gathered in this work could contribute to a better understanding of the impaired metabolic mechanisms and hopefully bring insights into the underlying neuropathology of psychiatric disorders.

Relationship between Erythrocyte Fatty Acid Composition and Psychopathology in the Vienna Omega-3 Study

This study investigated the relationship between erythrocyte membrane fatty acid (FA) levels and the severity of symptoms of individuals at ultra-high risk (UHR) for psychosis. Subjects of the present study consisted of 80 neuroleptic-naïve UHR patients. Partial correlation coefficients were calculated between baseline erythrocyte membrane FA levels, measured by gas chromatography, and scores on the Positive and Negative Syndrome Scale (PANSS), Global Assessment of Functioning Scale, and Montgomery–Asberg Depression Rating Scale (MADRS) after controlling for age, sex, smoking and cannabis use. Subjects were divided into three groups according to the predominance of positive or negative symptoms based on PANSS subscale scores; membrane FA levels in the three groups were then compared. More severe negative symptoms measured by PANSS were negatively correlated with two saturated FAs (myristic and margaric acids), one ω-9 monounsaturated FA (MUFA; nervonic acid), and one ω-3 polyunsaturated FA (PUFA; docosapentaenoic acid), and were positively correlated with two ω-9 MUFAs (eicosenoic and erucic acids) and two ω-6 PUFAs (γ-linolenic and docosadienoic acids). More severe positive symptoms measured by PANSS were correlated only with nervonic acid. No associations were observed between FAs and MADRS scores. In subjects with predominant negative symptoms, the sum of the ω-9 MUFAs and the ω-6:ω-3 FA ratio were both significantly higher than in those with predominant positive symptoms, whereas the sum of ω-3 PUFAs was significantly lower. In conclusion, abnormalities in FA metabolism may contribute to the neurobiology of psychopathology in UHR individuals. In particular, membrane FA alterations may play a role in negative symptoms, which are primary psychopathological manifestations of schizophrenia-related disability.

Pretreatment levels of the fatty acid handling proteins H-FABP and CD36 predict response to olanzapine in recent-onset schizophrenia patients

Traditional schizophrenia pharmacotherapy remains a subjective trial and error process involving administration, titration and switching of drugs multiple times until an adequate response is achieved. Despite this time-consuming and costly process, not all patients show an adequate response to treatment. As a consequence, relapse is a common occurrence and early intervention is hampered. Here, we have attempted to identify candidate blood biomarkers associated with drug response in 121 initially antipsychotic-free recent-onset schizophrenia patients treated with widely-used antipsychotics, namely olanzapine (n=40), quetiapine (n=23), risperidone (n=30) and a mixture of these drugs (n=28). Patients were recruited and investigated as two separate cohorts to allow biomarker validation. Data analysis showed the most significant relationship between pre-treatment levels of heart-type fatty acid binding protein (H-FABP) and response to olanzapine (p=0.008, F=8.6, β=70.4 in the discovery cohort and p=0.003, F=15.2, β=24.4 in the validation cohort, adjusted for relevant confounding variables). In a functional follow-up analysis of this finding, we tested an independent cohort of 10 patients treated with olanzapine and found that baseline levels of plasma H-FABP and expression of the binding partner for H-FABP, fatty acid translocase (CD36), on monocytes predicted the reduction of psychotic symptoms (p=0.040, F=6.0, β=116.3 and p=0.012, F=11.9, β=-0.0054, respectively). We also identified a set of serum molecules changed after treatment with antipsychotic medication, in particular olanzapine. These molecules are predominantly involved in cellular development and metabolism. Taken together, our findings suggest an association between biomarkers involved in fatty acid metabolism and response to olanzapine, while other proteins may serve as surrogate markers associated with drug efficacy and side effects.

Hippocampal Pruning as a New Theory of Schizophrenia Etiopathogenesis

Pruning in neurons has been suggested to be strongly involved in Schizophrenia's (SKZ) etiopathogenesis in recent biological, imaging, and genetic studies. We investigated the impact of protein-coding genes known to be involved in pruning, collected by a systematic literature research, in shaping the risk for SKZ in a case-control sample of 9,490 subjects (Psychiatric Genomics Consortium). Moreover, their modifications through evolution (humans, chimpanzees, and rats) and subcellular localization (as indicative of their biological function) were also investigated. We also performed a biological pathways (Gene Ontology) analysis. Genetics analyses found four genes (DLG1, NOS1, THBS4, and FADS1) and 17 pathways strongly involved in pruning and SKZ in previous literature findings to be significantly associated with the sample under analysis. The analysis of the subcellular localization found that secreted genes, and so regulatory ones, are the least conserved through evolution and also the most associated with SKZ. Their cell line and regional brain expression analysis found that their areas of primary expression are neuropil and the hippocampus, respectively. At the best of our knowledge, for the first time, we were able to describe the SKZ neurodevelopmental hypothesis starting from a single biological process. We can also hypothesize how alterations in pruning fine regulation and orchestration, strongly related with the evolutionary newest (and so more sensitive) secreted proteins, may be of particular relevance in the hippocampus. This early alteration may lead to a mis-structuration of neural connectivity, resulting in the different brain alteration that characterizes SKZ patients.

Omega-3 prevents behavior response and brain oxidative damage in the ketamine model of schizophrenia

Supplementation with omega-3 has been identified as an adjunctive alternative for the treatment of psychiatric disorders, in order to minimize symptoms. Considering the lack of understanding concerning the pathophysiology of schizophrenia, the present study hypothesized that omega 3 prevents the onset of symptoms similar to schizophrenia in young Wistar rats submitted to ketamine treatment. Moreover, the role of oxidative stress in this model was assessed. Omega-3 (0.8g/kg) or vehicle was given by orogastric gavage once daily. Both treatments were performed during 21days, starting at the 30th day of life in young rats. After 14days of treatment with omega-3 or vehicle, a concomitant treatment with saline or ketamine (25mg/kg ip daily) was started and maintained until the last day of the experiment. We evaluated the pre-pulse inhibition of the startle reflex, activity of antioxidant systems and damage to proteins and lipids. Our results demonstrate that supplementation of omega-3 prevented: decreased inhibition of startle reflex, damage to lipids in the hippocampus and striatum and damage to proteins in the prefrontal cortex. Furthermore, these changes are associated with decreased GPx in brain tissues evaluated. Together, our results suggest the prophylactic role of omega-3 against the outcome of symptoms associated with schizophrenia.

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.

Polyunsaturated fatty acids deficits are associated with psychotic state and negative symptoms in patients with schizophrenia

The study was aimed to examine membrane polyunsaturated fatty acids (PUFAs) profile in patients with schizophrenia (SZ) before and after antipsychotic medication and test their association with psychopathology. Erythrocyte membrane fatty acids were analysed by gas chromatography in 36 drug-free patients with SZ and 36 controls. Psychometric evaluation and blood sampling were achieved at baseline and after 3 months of antipsychotic treatment. At enrolment, levels of total PUFAs and arachidonic (AA) and docosahexaenoic (DHA) acids were significantly lower, but ω6/ω3 PUFAs ratio was higher in patients. AA and DHA were negatively related to the Andreason's scale for assessment of negative symptoms (SANS) score. DHA was inversely related to "alogia", "anhedonia", "avolition", and "blunted affect" subitems of SANS. After 3 months under typical antipsychotic drugs, fatty acid profile turned into comparable to controls in parallel with psychopathology improvement. Data indicate that PUFAs deficits are associated with psychotic state and negative symptoms of SZ.

A review of fatty acid profiles and antioxidant content in grass-fed and grain-fed beef

Growing consumer interest in grass-fed beef products has raised a number of questions with regard to the perceived differences in nutritional quality between grass-fed and grain-fed cattle. Research spanning three decades suggests that grass-based diets can significantly improve the fatty acid (FA) composition and antioxidant content of beef, albeit with variable impacts on overall palatability. Grass-based diets have been shown to enhance total conjugated linoleic acid (CLA) (C18:2) isomers, trans vaccenic acid (TVA) (C18:1 t11), a precursor to CLA, and omega-3 (n-3) FAs on a g/g fat basis. While the overall concentration of total SFAs is not different between feeding regimens, grass-finished beef tends toward a higher proportion of cholesterol neutral stearic FA (C18:0), and less cholesterol-elevating SFAs such as myristic (C14:0) and palmitic (C16:0) FAs. Several studies suggest that grass-based diets elevate precursors for Vitamin A and E, as well as cancer fighting antioxidants such as glutathione (GT) and superoxide dismutase (SOD) activity as compared to grain-fed contemporaries. Fat conscious consumers will also prefer the overall lower fat content of a grass-fed beef product. However, consumers should be aware that the differences in FA content will also give grass-fed beef a distinct grass flavor and unique cooking qualities that should be considered when making the transition from grain-fed beef. In addition, the fat from grass-finished beef may have a yellowish appearance from the elevated carotenoid content (precursor to Vitamin A). It is also noted that grain-fed beef consumers may achieve similar intakes of both n-3 and CLA through the consumption of higher fat grain-fed portions.

Oiling the brain: a review of randomized controlled trials of omega-3 fatty acids in psychopathology across the lifespan

Around one in four people suffer from mental illness at some stage in their lifetime. There is increasing awareness of the importance of nutrition, particularly omega-3 polyunsaturated fatty acids (n-3 PUFA), for optimal brain development and function. Hence in recent decades, researchers have explored effects of n-3 PUFA on mental health problems over the lifespan, from developmental disorders in childhood, to depression, aggression, and schizophrenia in adulthood, and cognitive decline, dementia and Alzheimer's disease in late adulthood. This review provides an updated overview of the published and the registered clinical trials that investigate effects of n-3 PUFA supplementation on mental health and behavior, highlighting methodological differences and issues.

Zinc and DHA have opposing effects on the expression levels of histones H3 and H4 in human neuronal cells

Zn and DHA have putative neuroprotective effects and these two essential nutrients are known to interact biochemically. We aimed to identify novel protein candidates that are differentially expressed in human neuronal cell line M17 in response to Zn and DHA that would explain the molecular basis of this interaction. Two-dimensional gel electrophoresis and MS were applied to identify major protein expression changes in the protein lysates of human Ml7 neuronal cells that had been grown in the presence and absence of Zn and DHA. Proteomic findings were further investigated using Western immunoblot and real-time PCR analyses. Four protein spots, which had significant differential expression, were identified and selected for in-gel trypsin digestion followed by matrix-assisted laser desorption ionisation MS analysis. The resultant peptide mass fingerprint for each spot allowed their respective identities to be deduced. Two human histone variants H3 and H4 were identified. Both H3 and H4 were downregulated by Zn in the absence of DHA (Zn effect) and upregulated by DHA (DHA effect) in the presence of Zn (physiological condition). These proteomic findings were further supported by Western immunoblot and real-time PCR analyses using H3- and H4-specific monoclonal antibodies and oligonucleotide primers, respectively. We propose that dietary Zn and DHA cause a global effect on gene expression, which is mediated by histones. Such novel information provides possible clues to the molecular basis of neuroprotection by Zn and DHA that may contribute to the future treatment, prevention and management of neurodegenerative diseases such as Alzheimer's disease.

Towards a nutritional approach for prevention of Alzheimer's disease: Biochemical and cellular aspects

Alzheimer's disease (AD) is a major public health concern in all countries. Although the precise cause of AD is still unknown, a growing body of evidence supports the notion that soluble amyloid beta-peptide (Abeta) may be the proximate cause of synaptic injuries and neuronal death early in the disease. AD patients display lower levels of docosahexaenoic acid (DHA, C22:6 ; n-3) in plasma and brain tissues as compared to age-matched controls. Furthermore, epidemiological studies suggest that high DHA intake might have protective properties against neurodegenerative diseases. These observations are supported by in vivo studies showing that DHA-rich diets limits the synaptic loss and cognitive defects induced by Abeta peptide. Although the molecular basis of these neuroprotective effects remains unknown, several mechanisms have been proposed such as (i) regulation of the expression of potentially protective genes, (ii) activation of anti-inflammatory pathways, (iii) modulation of functional properties of the synaptic membranes along with changes in their physicochemical and structural features.

Modulation of lipid rafts by Omega-3 fatty acids in inflammation and cancer: implications for use of lipids during nutrition support

Current understanding of biologic membrane structure and function is largely based on the concept of lipid rafts. Lipid rafts are composed primarily of tightly packed, liquid-ordered sphingolipids/cholesterol/saturated phospholipids that float in a sea of more unsaturated and loosely packed, liquid-disordered lipids. Lipid rafts have important clinical implications because many important membrane-signaling proteins are located within the raft regions of the membrane, and alterations in raft structure can alter activity of these signaling proteins. Because rafts are lipid-based, their composition, structure, and function are susceptible to manipulation by dietary components such as omega-3 polyunsaturated fatty acids and by cholesterol depletion. We review how alteration of raft lipids affects the raft/nonraft localization and hence the function of several proteins involved in cell signaling. We focus our discussion of raft-signaling proteins on inflammation and cancer.

Polyunsaturated fatty acid supplementation for schizophrenia

BACKGROUND

Limited evidence supports a hypothesis suggesting that schizophrenic symptoms may be the result of altered neuronal membrane structure and metabolism. The structure and metabolism is dependent on blood plasma levels of certain essential fatty acids and their metabolites.

OBJECTIVES

To review the effects of polyunsaturated fatty acids for people with schizophrenia.

SEARCH STRATEGY

We have updated the initial searches of 1998 and 2002 (Cochrane Schizophrenia Group's Register, July 2005), and where necessary, we contacted authors and relevant pharmaceutical companies.

SELECTION CRITERIA

We included all randomised clinical trials of polyunsaturated fatty acid treatment for schizophrenia.

DATA COLLECTION AND ANALYSIS

Working independently, we selected studies for quality assessment and extracted relevant data. We analysed on an intention-to-treat basis. Where possible and appropriate we calculated the Relative Risk (RR) and their 95% confidence intervals (CI) and estimated the number needed to treat (NNT). For continuous data we calculated weighted mean differences (WMD) and their 95% confidence intervals. We also inspected the data for heterogeneity.

MAIN RESULTS

When any dose omega-3 (E-EPA or EPA) is compared with placebo, small short trials suggest that the need for neuroleptics appears to be reduced for people allocated omega-3 supplementation (n=30, 1 RCT, RR 0.73 CI 0.54 to 1.00) and mental state may improve (n=30, 1 RCT, RR not gaining 25% change in PANSS scores 0.54 CI 0.30 to 0.96, NNT3 CI 2-29). There are no differences in the number of people leaving the study early (n=271, 4 RCTs, RR 0.91 CI 0.36 to 2.33). There are few data on the comparison of any dose omega-6 (GLA) with placebo. For movement disorder outcomes, the only small study we found does not show any difference for average short-term endpoint AIMS score (n=16, 1 RCT, MD 1.30 CI -1.96 to 4.56). When any dose omega 3 (E-EPA or EPA) is compared with any dose omega-3 (DHA) there is no clear difference for mental state outcome of not gaining 25% change in PANSS scores (n=31, 1 RCT, RR 0.66 CI 0.39 to 1.11). When different doses of omega-3 (E-EPA) are compared with placebo there are no differences in measures of global and mental state between the studies. For the outcome of 'experiencing at least one adverse effect' no differences between groups are found for any dose (1g/day E-EPA vs placebo n=63 1 RCT, RR 0.97 CI 0.60 to 1.56; 2g/day E-EPA vs placebo n=63 1 RCT, RR 0.67 CI 0.37 to 1.20; 4g/day E-EPA vs placebo n=58, 1 RCT, RR 1.15 CI 0.72 to 1.82).

AUTHORS' CONCLUSIONS

Two updates of this review have resulted in more included studies but relatively little useful additional data. The results remain inconclusive. The new trials all compare the omega-3 polyunsaturated fatty acids, in particular eicosapentaenoic acid and its ester, ethyl-eicosapentaenoic acid. The use of omega-3 polyunsaturated fatty acids for schizophrenia still remains experimental and this review highlights the need for large well designed, conducted and reported studies.

A role for direct interactions in the modulation of rhodopsin by omega-3 polyunsaturated lipids

Rhodopsin, the G protein-coupled receptor primarily responsible for sensing light, is found in an environment rich in polyunsaturated lipid chains and cholesterol. Biophysical experiments have shown that lipid unsaturation and cholesterol both have significant effects on rhodopsin's stability and function; omega-3 polyunsaturated chains, such as docosahexaenoic acid (DHA), destabilize rhodopsin and enhance the kinetics of the photocycle, whereas cholesterol has the opposite effect. Here, we use molecular dynamics simulations to investigate the possibility that polyunsaturated chains modulate rhodopsin stability and kinetics via specific direct interactions. By analyzing the results of 26 independent 100-ns simulations of dark-adapted rhodopsin, we found that DHA routinely forms tight associations with the protein in a small number of specific locations qualitatively different from the nonspecific interactions made by saturated chains and cholesterol. Furthermore, the presence of tightly packed DHA molecules tends to weaken the interhelical packing. These results are consistent with recent NMR work, which proposes that rhodopsin binds DHA, and they suggest a molecular rationale for DHA's effects on rhodopsin stability and kinetics.

[The role of nutritional factors on the structure and function of the brain: an update on dietary requirements]

The brain is an organ elaborated and functioning from substances present in the diet. Dietary regulation of blood glucose level (via ingestion of food with a low glycemic index ensuring a low insulin level) improves the quality and duration of intellectual performance, if only because at rest the adult brain consumes 50 p. 100 of dietary carbohydrates, 80 p. 100 of them for energy purposes. The nature of the amino acid composition of dietary proteins contributes to good cerebral function; tryptophan plays a special role. Many indispensable amino acids present in dietary proteins help to elaborate neurotransmitters and neuromodulators. Omega-3 fatty acids provided the first coherent experimental demonstration of the effect of dietary nutrients on the structure and function of the brain. First it was shown that the differentiation and functioning of cultured brain cells requires omega-3 fatty acids. It was then demonstrated that alpha-linolenic acid (ALA) deficiency alters the course of brain development, perturbs the composition and physicochemical properties of brain cell membranes, neurones, oligodendrocytes, and astrocytes (ALA). This leads to physicochemical modifications, induces biochemical and physiological perturbations, and results in neurosensory and behavioral upset. Consequently, the nature of polyunsaturated fatty acids (in particular omega-3) present in formula milks for infants (premature and term) conditions the visual and cerebral abilities, including intellectual abilities. Moreover, dietary omega-3 fatty acids are certainly involved in the prevention of some aspects of cardiovascular disease (including at the level of cerebral vascularization), and in some neuropsychiatric disorders, particularly depression, as well as in dementia, notably Alzheimer's disease. Their deficiency can prevent the satisfactory renewal of membranes and thus accelerate cerebral aging. Iron is necessary to ensure oxygenation, to produce energy in the cerebral parenchyma, and for the synthesis of neurotransmitters. The iodine provided by the thyroid hormone ensures the energy metabolism of the cerebral cells. The absence of iodine during pregnancy induces severe cerebral dysfunction, leading to cretinism. Manganese, copper, and zinc participate in enzymatic mechanisms that protect against free radicals, toxic derivatives of oxygen. The use of glucose by nervous tissue implies the presence of vitamin B1. Vitamin B9 preserves memory during aging, and with vitamin B12 delays the onset of signs of dementia, provided it is administered in a precise clinical window, at the onset of the first symptoms. Vitamins B6 and B12, among others, are directly involved in the synthesis of neurotransmitters. Nerve endings contain the highest concentrations of vitamin C in the human body. Among various vitamin E components, only alpha-tocopherol is involved in nervous membranes. The objective of this update is to give an overview of the effects of dietary nutrients on the structure and certain functions of the brain.

Docosahexaenoic acid-enriched egg consumption induces accretion of arachidonic acid in erythrocytes of elderly patients

Many studies in humans volunteers have shown that dietary docosahexaenoic acid (DHA) supplied as triacylglycerol can increase DHA levels in blood lipids but often strongly decreases those of arachidonic acid (AA). The aim of the present study was to determine the effect of dietary supplementation with egg-yolk powder enriched in DHA, corresponding to the French recommended dietary allowance for DHA, on the blood lipid status of an elderly population. Institutionalised elderly individuals aged between 63 and 93 years consumed an egg product enriched in DHA (150 mg/d) once daily for 9 months. Plasma lipids and the fatty acid composition of erythrocyte membranes were determined every 3 months. The supplementation induced an increase in the PUFA content of plasma and erythrocyte membranes which was +14.5 and +25.3 %, respectively, at 9 months. This effect was mainly due to the level of DHA and, unexpectedly, to that of AA which continuously increased. This increase in AA was the result of an increased dietary intake (+50 mg/d) and very probably of an increased biosynthesis as demonstrated by the behaviour of di-homo-gamma-linolenic acid. The supplementation resulted in a blood PUFA status comparable with that of young healthy controls. The data are consistent with a strong regulatory action of the dietary treatment on the subjects' lipid metabolism.

Eicosapentaenoic acid: biosynthetic routes and the potential for synthesis in transgenic plants

Long chain polyunsaturated fatty acids are now known to play important roles in human health. In particular, eicosapentaenoic acid (20:5Delta(5,8,11,14,17); n-3: EPA) is implicated as a protective agent in a range of pathologies such as cardiovascular disease and Metabolic Syndrome (Syndrome X). Eicosapentaenoic acid is currently sourced from fish oils, the presence of this fatty acid being due to the dietary piscine consumption of EPA-synthesising micro-algae. The biosynthetic pathway of EPA has been elucidated, and contains several alternative metabolic routes. Progress in using "reverse engineering" to transgenically mobilize the trait(s) for EPA are considered. In particular, the prospect of producing this important polyunsaturated fatty acid in transgenic oilseeds is highlighted, as is the urgent need for a sustainable replacement for diminishing fish stocks.

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.

Docosahexaenoic acid: membrane properties of a unique fatty acid

Docosahexaenoic acid (DHA) with 22-carbons and 6 double bonds is the extreme example of an omega-3 polyunsaturated fatty acid (PUFA). DHA has strong medical implications since its dietary presence has been positively linked to the prevention of numerous human afflictions including cancer and heart disease. The PUFA, moreover, is essential to neurological function. It is remarkable that one simple molecule has been reported to affect so many seemingly unrelated biological processes. Although details of a molecular mode of action remain elusive, DHA must be acting at a fundamental level common to many tissues that is related to the high degree of conformational flexibility that the multiple double bonds have been identified to confer. One likely target for DHA action is at the cell membrane where the fatty acid is known to readily incorporate into membrane phospholipids. Once esterified into phospholipids DHA has been demonstrated to significantly alter many basic properties of membranes including acyl chain order and "fluidity", phase behavior, elastic compressibility, permeability, fusion, flip-flop and protein activity. It is concluded that DHA's interaction with other membrane lipids, particularly cholesterol, may play a prominent role in modulating the local structure and function of cell membranes.

Polyunsaturated fatty acid supplementation for schizophrenia

BACKGROUND

Limited evidence supports a hypothesis suggesting that schizophrenic symptoms may be the result of altered neuronal membrane structure and metabolism. This structure and metabolism is dependent on blood plasma levels of certain essential fatty acids and their metabolites.

OBJECTIVES

To review the effects polyunsaturated fatty acids for people with schizophrenia.

SEARCH STRATEGY

The initial search of 1998 was updated. We searched the Cochrane Schizophrenia Group's Register (July 2002), and authors of included studies and relevant pharmaceutical companies were contacted.

SELECTION CRITERIA

All randomised clinical trials of polyunsaturated fatty acid treatment for schizophrenia.

DATA COLLECTION AND ANALYSIS

Reviewers, working independently, selected, quality assessed, and extracted relevant data. Analysis was on an intention-to-treat basis. Where possible and appropriate Relative Risk (RR) and their 95% confidence intervals (CI) were calculated and the number needed to treat (NNT) estimated. For continuous data, weighted mean differences (WMD) and their 95% confidence intervals were calculated. Data were inspected for heterogeneity.

MAIN RESULTS

Five short small studies (n=313) were included. One small study (n=30) suggested that an omega-3 EFA (ecisapentenoic acid (EPA) enriched oil) may have some antipsychotic properties when compared with placebo, even if not given as a supplement to standard drugs (RR not needing antipsychotic drugs 0.73 CI 0.54 to 1.00; RR less than 25% improvement in PANSS 0.54 CI 0.3 to 0.96, NNT 3 CI 2 to 29). Other studies comparing omega-3 EFA's with placebo as a supplement to antipsychotics were too small to be conclusive. There was a suggestion that people already on antipsychotics when given omega-3 EFA supplementation had greater improvement of mental state compared to those receiving a placebo supplementation but the result were not significant (n=29, 1 RCT, RR <25% improvement in PANSS 0.62 CI 0.37 to 1.05). However, the mental state of both medicated and un-medicated patients was significantly better for those receiving omega-3 EFA supplementation (n=59, 2 RCTs, RR <25% improved on PANSS 0.58 CI 0.39 to 0.85, NNT 3 CI 2-8). Medium term data, however, did not favour either group (n=87, 1 RCT, MD PANSS endpoint -1.0 CI -8.15 to 6.15). All studies had low attrition (<10% total, n=271, 4 RCTs, RR leaving the study early 0.91 CI 0.36 to 2.33). Another study (n=31) comparing two types of omega-3 EFA's, ecisapentenoic acid enriched oil and docosahexanoic acid oil, also found no differences between these two EFA's in measures of mental state. One small (n=16) study investigated the effects of an omega-6 EFA compared with placebo for tardive dyskinesia and found no clear effects. There is not a clear dose response to omega-3 supplementation. Adverse effects seem rare but diarrhoea may be a problem in the medium term.

REVIEWER'S CONCLUSIONS

The use of omega-3 polyunsaturated fatty acids for schizophrenia remains experimental and large well designed, conducted and reported studies are indicated and needed.

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.

Formation of inverted hexagonal phase in SDPE as observed by solid-state (31)P NMR

Docosahexaenoic acid (DHA), the longest and most unsaturated fatty acid commonly found in biological membranes, is known to affect various membrane properties. In a variety of cell membranes, DHA is primarily incorporated in phosphatidylethanolamines, where its function remains poorly understood. In order to understand the role of DHA in influencing membrane structure, we utilize (31)P NMR spectroscopy to study the phase behavior of 1-stearoyl-2-docosahexaenoyl-sn-glycerophosphoethanolamine (SDPE) in comparison to 1-palmitoyl-2-oleoyl-sn-glycerophosphoethanolamine (POPE) from 20 to 50 degrees C. Spectra of SDPE phospholipids show the formation of inverted hexagonal phase (H(II)) from 20 to 50 degrees C; in contrast, POPE mutilamellar dispersions exist in a lamellar liquid-crystalline phase (L(alpha)) at the same temperatures. The ability of SDPE to adopt nonbilayer phases at a physiological temperature may indicate its role in imparting negative curvature stress upon the membrane and may affect local molecular organization including the formation of lipid microdomains within biological membranes.

Long-term changes in adipose tissue in human disease

Redistribution of white adipose tissue is a long-term symptom of several chronic diseases. Although the roles of adipocytes in acute illness have been thoroughly studied, how or why short-term responses of adipose tissue to disease sometimes produce long-term redistribution, and the causal relationship between the anatomical changes and the associated metabolic syndromes are poorly understood. The present paper reviews explanations for the redistribution of adipose tissue after infection with HIV, and in Crohn's disease; both conditions that share the peculiarity of selective expansion of certain adipose depots while others are depleted. HIV adipose tissue redistribution syndrome (HARS) develops gradually after several months of infection with the HIV both in untreated patients and in those taking protease inhibitors and nucleoside reverse transcriptase inhibitors. Some current theories about the causes of HARS are critically assessed, and reasons presented for implicating local interactions between the immune system and perinodal adipocytes. Some evolutionary aspects of conspicuous long-term changes in the distribution of human adipose tissue are discussed. Adipose tissue acts as a social signal, indicating dietary history and previous exposure to pathogens. A distinctive symptom of Crohn's disease is selective enlargement of the mesenteric adipose tissue near the diseased lymph nodes and intestine. Perinodal adipocytes have site-specific properties not found in adipocytes from nodeless depots, such as perirenal and epididymal, that may equip them to interact locally with lymph-node lymphoid cells, making polyunsaturated fatty acids selectively and rapidly available to activated immune cells. Studies of the time course of activation of perinodal adipocytes via the lymph nodes they enclose indicate that prolonged or frequent stimulation recruits more adipocytes to control by immune cells, which may lead to selective enlargement of node-containing depots. These concepts suggest hypotheses about HARS and the anomalous development of mesenteric adipose tissue in Crohn's disease that could form the basis for further investigations.

Significantly reduced docosahexaenoic and docosapentaenoic acid concentrations in erythrocyte membranes from schizophrenic patients compared with a carefully matched control group

BACKGROUND

Fatty acid research in schizophrenia has demonstrated an altered cell membrane phospholipid metabolism. Erythrocyte membrane phospholipid composition closest reflects that of neuronal membranes.

METHODS

(Poly)(un)saturated fatty acid concentrations were measured in the erythrocyte membranes of 19, consecutively admitted, medicated young schizophrenic patients and then compared with matched control subjects. Psychiatric symptomatology was rated with the Positive and Negative Symptom Scale and Montgomery-Asberg Depression Rating Scale. Because diet, hormones, and cannabis influence fatty acid metabolism, we included these factors in our study.

RESULTS

The most distinctive findings concerned the omega-3 series: C22:5 omega-3, C22:6 omega-3 (docosahexaenoic acid), and the sum of omega-3 fatty acids were significantly decreased. Interestingly, C20:4 omega-6 (arachidonic acid) was not lowered. In the omega-9 series, higher levels of C22:1 omega-9 and lower levels its elongation product, C24:1 omega-9 (nervonic acid), were found. Interestingly, the other arm of the desaturation-elongation sequence of C18:1 omega-9, C20:3 omega-9, was lower in patients. The total omega-9 fatty acid levels were also lower in patients.

CONCLUSIONS

Significant differences in erythrocyte fatty acid composition were found. The differences were not due to diet or hormonal status and could not be explained by the medication or cannabis use. No consistent pattern emerged from the different fatty acid abnormalities and the clinical symptom scores.

Is platelet release of 2-arachidonoyl-glycerol a mediator of cognitive deficits? An endocannabinoid theory of schizophrenia and arousal

The discovery of blood platelet's ability to release 2-arachidonoyl-glycerol (2-AG), a highly lipophilic cannabinoid molecule may usher in a radical change in our understanding of how the vascular system interacts with the brain. This paper primarily extends Kayai's second messenger imbalance theory of schizophrenia, suggesting that 2-AG is the unidentified second messenger system that Kayai theorized was unbalanced in schizophrenia; furthermore, that a chronic over-release of 2-AG by platelets may be a causal factor in the cognitive deficits associated with negative symptom schizophrenia. Finally, platelet release of 2-AG may also be the causal agent in the cognitive deficits associated with states of high arousal, shock and in other conditions that feature heightened platelet activation. As such, heightened platelet activation may be a profoundly important vector for changing endogenous cannabinoid levels in the brain.

Fatty acid analysis of blood plasma of patients with Alzheimer's disease, other types of dementia, and cognitive impairment

Fatty acid differences, including docosahexaenoic acid (DHA; 22:6n-3) have been shown in the brains of Alzheimer's patients (AD) as compared with normal age-matched individuals. Furthermore, low serum DHA is a significant risk factor for the development of AD. The relative concentration of DHA and other fatty acids, however, in the plasma of AD patients compared with patients with other kinds of dementias (other dementias; OD), patients who are cognitively impaired but nondemented (CIND), or normal patients is not known. In this study we analyzed the total phospholipid, phosphatidylcholine (PC), phosphatidylethanolamine (PE), and lysophosphatidylcholine (lysoPC) fractions of plasma from patients diagnosed with AD, OD, or CIND and compared them with a group of elderly control subjects with normal cognitive functioning. Plasma phospholipid and PC levels of 20:5n-3, DHA, total n-3 fatty acids, and the n-3/n-6 ratio were lower in the AD, OD, and CIND groups. Plasma phospholipid 24:0 was lower in the AD, OD, and CIND groups as compared with the group of control patients, and total n-6 fatty acid levels were higher in the AD and CIND groups only. In the plasma PE fraction, levels of 20:5n-3, DHA, and the total n-3 fatty acid levels were significantly lower in the AD, OD, and CIND groups. DHA levels were lower in the lysoPC fraction of CIND individuals only. There were no other differences in the fatty acid compositions of the different phospholipid fractions. Therefore, in AD, OD, and CIND individuals, low levels of n-3 fatty acids in the plasma may be a risk factor for cognitive impairment and/or dementia. Interestingly, a decreased level of plasma DHA was not limited to the AD patients but appears to be common in cognitive impairment with aging.

Docosahexanoic acid and omega-3 fatty acids in depression

Geographic areas where consumption of DHA is high are associated with decreased rates of depression. DHA deficiency states, such as alcoholism and the postpartum period, also are linked with depression. Individuals with major depression have marked depletions in omega-3 FAs (especially DHA) in erythrocyte phospholipids compared with controls. These data suggest that DHA may be associated with depression, and the limited data available on supplementation with DHA or other omega-3 FAs seem to support the hypothesis that DHA may have psychotropic effects. Overall, the use of EFAs is promising, particularly in view of the many illnesses potentially treatable with these substances; however, larger, carefully designed studies are needed to establish whether DHA is an effective and safe antidepressant, mood stabilizer, or antipsychotic. A few preliminary trials of DHA are in progress, but no studies comparing DHA against placebo or against an established antidepressant have been carried out. Studies to address this issue are being developed at the Massachusetts General Hospital. Studies likely will require escalating doses of DHA, eventually reaching high levels so as to ensure that patients will avoid a potentially ineffective subclinical dose. Careful monitoring of dietary intake among subjects also will necessary because a high intake of omega-3-rich foods may confound results. Finally, large-scale, placebo-controlled, double-blind trials comparing the efficacy and safety of DHA against standard antidepressants are required before psychiatrists can recommend DHA therapy as effective and safe for the treatment of depression and other mood disorders. Given the popularity of self-medication by patients who already are taking marketed antidepressants, studies examining the use of DHA as an augmentor to standard antidepressants may answer whether DHA can occupy a niche as an augmenting agent for patients who have made a partial response or have not responded to conventional antidepressants. Considering that natural medications generally seem best for treating mild to moderate illness, the role of DHA as a therapy for minor and subsyndromal depression also should be considered. It is hoped that studies of these types will help to clarify some of the knowledge gaps outlined in this article.

Co-distribution of sensory gating and impaired niacin flush response in the parents of schizophrenics

Complex illnesses may result from the interaction or addition of multiple factors. We examined the familial co-distribution of two abnormalities common in schizophrenia: impaired auditory sensory gating and impaired flush response to niacin. In ten families, the obligate carrier parent had sensory-gating deficits, while eight of the ten parents without a family history of schizophrenia had impaired flush response. No parents had both deficits. The data are consistent with a theory suggesting the interaction of these two factors in some cases of schizophrenia.

Neurobiological abnormalities in the relatives of schizophrenics

The inheritance of a complex illness such as schizophrenia likely involves the segregation of genetic factors, in combination with non-genetic or environmental abnormalities. This paper reviews several family studies of biological and clinical aspects of schizophrenia, that have attempted to observe such segregation in relationship to family history of schizophrenia to identify which factors appear to be related to the transmission of genetic risk.

Pathophysiological effects of dietary essential fatty acid balance on neural systems

Dietary fatty acid balance has been revealed to affect neural functions as well as chronic diseases such as cancer, cerebro- and cardiovascular diseases, and allergic hyper-reactivity. In this review, we focused on the pathophysiological effects of n-6 and n-3 fatty acids on brain functions. Long-term n-3 fatty acid deficiency in the presence of n-6 fatty acids has been shown to affect learning behavior, drug sensitivity and retinal functions. Some membrane enzymes and ion channel functions have been shown in experimental animals to be regulated by membrane fatty acid modifications. We also summarized the effects of these fatty acids in diets on human psychotic aspects and brain diseases. Although biochemical mechanisms remain to be elucidated, investigations on the effect of dietary fatty acids on neural networks may provide an important clue to clarify complex brain functions.

Could diet be used to reduce the risk of developing Alzheimer's disease?

Researchers have recently reported a possible inverse relationship between taking steroids or non-steroidal anti-inflammatory drugs, or both, and the development of Alzheimer's disease. In this article it is hypothesized that the reduction in the human body of the amount of available arachidonic acid, the precursor of inflammatory eicosanoids, by dietary methods might offer a path to prevention of Alzheimer's disease without resorting to drugs having potentially harmful side effects, and without inhibiting the production of highly important, non-inflammatory eicosanoids.