How Does Exposure to Dementia Relate to Subjective Cognition? A Systematic Review

Background and Objectives: Subjective cognitive decline (SCD) may be indicative of future objective cognitive decline. However, factors other than objective cognitive performance may influence SCD. This review addresses whether family history or close, nonfamilial exposure to dementia is associated with self-reported SCD. Research Design and Methods: Searches were conducted in PubMed, PsycINFO, Web of Science, and the Dissertations and Theses database. Eligible articles included measures of self-reported cognition for community-dwelling middle-aged or older adults (40+ years) not diagnosed with dementia, and who had either a family history of dementia, a family member, spouse, or close friend with dementia. The quality of evidence was evaluated using the LEGEND Appraisal Tool. Evidence was synthesized narratively. Results: A total of 32 articles were included, with 28 rated as good quality. Across studies, the relationship between dementia exposure and SCD was inconsistent. A significant association between exposure and SCD was found in 6 studies; however, 17 reviewed studies found no evidence of a relationship. The remaining 9 studies found mixed associations. Modifying factors that could potentially influence these associations were exploratorily identified among studies to provide context to our results. These factors included dementia worry, emotional closeness, and measurement sensitivity. Discussion and Implications: Findings of this review suggest that both first-degree relatives and spouses of persons with dementia may have an increased likelihood of reporting SCD, although the current heterogeneity in definitions of exposure to dementia and SCD may influence these findings. In addition to the relationship between dementia exposure and SCD, future research should examine potential modifiers, including meaning attributed to exposure, as identifying how these perceptions affect cognition may promote early intervention.