Lower plasma DHEAS and BDNF levels as indicators of cognitive decline

Gradual loss of cognitive abilities is common during ageing but might also result in mild cognitive impairment and dementia. Research suggests that neurotrophins, such as brain derived neurotrophic factor (BDNF), and neurosteroids, such as dehydroepiandrosterone (DHEA) and its sulphate (DHEAS), play crucial role in cognitive functions and are often dysregulated in neurocognitive disorders. This study aimed to investigate variations in the genes for BDNF and sulfotransferase 2A1 (SULT2A1), the enzyme converting DHEA into DHEAS, as well as plasma BDNF and DHEAS levels, in individuals with normal cognition, and mild, moderate, and severe cognitive impairment. Cognitive functions of 453 participants were evaluated using Mini-Mental State Examination (MMSE) and Clock Drawing test (CDT). Genotyping of BDNF (rs6265) and SULT2A1 (rs2637125) polymorphisms was conducted, and plasma BDNF and DHEAS concentrations were determined by enzyme-linked immunosorbent assays (ELISA). Obtained results demonstrated that participants with moderate to severe cognitive impairment had significantly lower plasma BDNF and DHEAS levels, compared to individuals with normal cognition. In contrast to DHEAS, BDNF changes were more pronounced in men than in women. However, no significant associations of BDNF rs6265 and SULT2A1 rs2637125 polymorphisms with cognitive decline, or with plasma BDNF and DHEAS levels, respectively, were observed. Compared to CDT, MMSE was superior in distinguishing plasma BDNF and DHEAS variations, especially between individuals with mild and moderate to severe cognitive impairment. Further studies should investigate the potential of BDNF and DHEAS as peripheral biomarkers of cognitive decline and possible benefits of their replacement therapy in neurocognitive disorders.