Association between reduced plasma BDNF concentration and MMSE scores in both chronic schizophrenia and mild cognitive impairment.

Reduced brain derived neurotrophic factor (BDNF) concentration is reported to be associated with a cognitive decline in schizophrenia, depending on the stage of the disease. Aim of the study was to examine the possible association between plasma BDNF and cognitive decline in chronic stable schizophrenia and mild cognitive impairment (MCI). The study included 123 inpatients of both sexes with schizophrenia, 123 patients with MCI and 208 healthy control subjects. Cognitive abilities were assessed using mini mental state examination (MMSE), Clock Drawing test (CDT) and cognitive subscale of the Positive and Negative Syndrome Scale (PANSS). Plasma BDNF concentration was determined using ELISA. BDNF concentration was lower in patients with schizophrenia and MCI compared to age-matched healthy controls and was similar in carriers of different BDNF Val/66Met genotypes. The MMSE and CDT scores were lower in patients with schizophrenia compared to healthy controls and subjects with MCI. Reduced plasma BDNF was significantly associated with lower MMSE scores in all subjects. BDNF concentration in patients with schizophrenia was not affected by clinical and demographic factors. BDNF Val66Met polymorphism was not associated with the MMSE scores in all participants. Further studies should include longitudinal follow-up and other cognitive scales to confirm these results and offer cognition-improving strategies to prevent cognitive decline in chronic schizophrenia.