Peripheral brain-derived neurotrophic factor is reduced in stroke survivors with cognitive impairment

Stroke presents a huge burden both globally and locally. Very few studies have evaluated cognitive impairment following stroke in Africa. This study evaluated cognitive impairment in stroke survivors and examined its relationship with peripheral blood levels of brain-derived neurotrophic factor (BDNF). It is hypothesized that serum BDNF levels significantly correlate with cognitive impairment. Cognition was assessed in 47 stroke survivors and 35 normal subjects using the Mini Mental State Examination (MMSE). Serum BDNF concentrations were determined using BDNF ELISA kits. Data were expressed as median (10^th-90^th percentiles) and analysed using non-parametric tests on SPSS statistics. The stroke survivors and controls were middle aged (in their fifties), with a median stroke duration of 10 months. The MMSE scores were significantly different between the stroke survivors and controls. The difference in serum BDNF values for the stroke survivors and controls was also statistically significant. About three quarters of the stroke survivors had mild or moderate cognitive impairment, which had a moderate positive relationship with serum BDNF levels. Our conclusion is that the very high prevalence of cognitive impairment observed during the period 10 months post stroke was associated, not with any of the socio-demographic factors in the subjects studied, but rather with reduced levels of brain-derived neurotrophic factor in the peripheral blood of stroke survivors.