There were three main findings in this study: (1) compared with age-matched healthy elderly, serum BDNF levels were significantly lower in LLS patients; (2) LLS patients displayed extensive cognitive impairments in all RBANS total and domain scores except for visuospatial/constructional domain; (3) BDNF levels were associated with attention in LLS patients. Here, BDNF is linked to Cognitive impairment.