Our previous study showed that metabolic abnormalities reduced the levels of
brain-derived neurotrophic factor (
BDNF) and deteriorated cognitive performance in patients with
schizophrenia.
Inflammation may play a key role in this process.
Omega-3 fatty acids have been documented to ameliorate
inflammation. Therefore, we hypothesized that
omega-3 fatty acids may be of value in enhancing
BDNF levels and improving cognitive function in patients with
schizophrenia with
metabolic syndrome (MetS). We recruited 80 patients with both
schizophrenia and MetS who received long-term
olanzapine monotherapy. The
enzyme-linked
immunosorbent assay was used to measure the plasma levels of
C-reactive protein (CRP),
interleukin-6 (IL-6) and
tumor necrosis factor-alpha (TNF-α). The patients were randomly assigned to the OMG-3 group (n = 40) or the placebo group (n = 40). Of the 80 patients who consented to the study, 72 completed this 12-week RCT. The primary outcome was the changes from baseline to 12 weeks in clinical characteristics and the levels of
BDNF, CRP,
IL-6 and TNF-α. There was a significant correlation between
omega-3 fatty acid treatment and enhanced delayed memory factor in the RBANS assessment (Fgroup×time = 6.82; df = 1, 66; P = 0.01) when the patients completed this study. Along with cognitive improvement,
omega-3 fatty acids enhanced
BDNF (Fgroup×time = 4.93; df = 1, 66; P = 0.03) and reduced CRP (Fgroup×time = 17.11; df = 1, 66; P < 0.01),
IL-6 (Fgroup×time = 9.71; df = 1, 66; P < 0.004) and TNF-α (Fgroup×time = 6.71; df = 1, 66; P = 0.012) levels after 12 weeks of treatment. The changes in
BDNF levels are negatively correlated with the changes in TNF-α levels (r = -0.37, P = 0.03) but not with the changes in CRP and
IL-6 levels. Our findings provide suggestive evidence that
omega-3 fatty acids have beneficial effects on cognitive function in patients with MetS, which is paralleled by enhanced
BDNF levels.