PUFA distributions suggest two schizophrenia endophenotypes
MedWire News: Schizophrenia patients have a bimodal distribution of polyunsaturated fatty acids (PUFA) in red blood cells (RBCs) that may point to the existence of two distinct endophenotypes, say Norwegian researchers.
Abnormalities in schizophrenia have previously been linked to disturbed membrane phospholipids metabolism and a deficient redox regulatory system. Two previous studies demonstrated a bimodal distribution of RBC PUFA in schizophrenia patients, but the findings have not been reproduced.
Håvard Bentsen, from Diakonhjemmet Hospital in Oslo, and colleagues measured RBC fatty acid levels in 97 patients with schizophrenia, schizoaffective disorder, or schizophreniform disorder aged, 18-39 years, at two intervals, 16 weeks apart. They also assessed fatty acid levels in 20 healthy controls aged 18-39 years.
At baseline, the distribution of RBC PUFA levels in patients was bimodal, primarily due to bimodal arachidonic acid and docosahexaenoic acid distribution. The low PUFA distribution had a probability of 0.30, a mean of 101.7 µg/g, and a standard deviation (SD) of 50.5 µg/g. The equivalent figures for the high distribution were 0.70, 440.9 µg/g, and 121.6 µg/g, respectively.
The researchers calculated a mean trough PUFA level between the two distribution peaks of 200 µg/g. They report that 30% of patients had a PUFA value below and 70% had a PUFA value above this level. PUFA values did not change significantly during 16 weeks of treatment with ethyl-eicosapentaenoate 2 g a day, or alpha-tocopherol 364 mg plus ascorbic acid 1000 mg a day, or placebo.
Smoking, gender, antipsychotic medication, and dietary factors were unrelated to bimodal distribution, whereas alpha-tocopherol was a significant predictor of PUFA levels, such that 22% of low PUFA patients had lipid-adjusted alpha-tocopherol levels below the healthy reference value and 44% of high PUFA patients had levels above the healthy reference value.
Noting that RBC PUFA levels had a unimodal distribution in healthy controls, the team writes in the journal Biological Psychiatry: "Both PUFA groups were prevalent and may define two distinct endophenotypes of the disorders.
"Endogenous deficiencies of redox regulation or synthesis of long-chain PUFA in the low PUFA group may explain our findings." Free abstract: http://dx.doi.org/10.1016/j.biopsych.2011.02.011
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By Liam Davenport