BDNF and Mental deterioration: Several inflammatory markers (e.g., IL-1β, IL-2, and GM-CSF) were linked to poorer performance on neuropsychological tests but fewer perceived difficulties [36,38,39], whereas BDNF variants, circulating BDNF, and COMT polymorphisms were more robustly tied to self-reported cognitive decline than to objective deficits [54,55,73,74].