Protective factors for Subjective Cognitive Decline Individuals: Trajectories and changes in a longitudinal study with Italian elderly

Background: Many different factors have been hypothesized to modulate cognition in an aging population according to their functioning at baseline. Methods: This retrospective study quantifies the relative contribution of age and sex as demographic factors, comorbidity, education, and occupation (classified with the International Standard Classification of Occupation, ISCO-08) as cognitive reserve (CR) proxies in accounting for cognitive aging. All participants (3,081) were evaluated at baseline with a complete neuropsychological test battery (T1) and those with unimpaired profiles were classified as Subjective Cognitive Decline, those mildly impaired as Mild Neurocognitive Decline, and those severely impaired as Major Neurocognitive Decline. From the first assessment 543 individuals were assessed a second time (T2), and 125 a third time (T3). Depending on whether they maintained or worsened their profile, based on their initial performance, participants were then classified as resistant or declining. Results: At baseline, all individuals showed education and occupation as the best predictors of performance, in addition to age. Furthermore, across assessments, the resistant had higher levels of education and occupation than the declining. In particular, the Subjective Cognitive Decline, and all other groups included the most severely impaired one, education, and occupation predicted cognitive performance. Conclusions: This study highlights the role of working activity in protecting from cognitive decline across all fragile elderly groups and even more so the individuals who are at very high risk of decline.