Prevalence and determinants of subjective cognitive decline in a representative Greek elderly population

Objectives: We studied the prevalence of subjective cognitive decline (SCD) and its determinants in a sample of 1456 cognitively normal Greek adults ≥65 years old.

Methods/design: Subjects were evaluated by a multidisciplinary team on their neurological, medical, neuropsychological, and lifestyle profile to reach consensus diagnoses. We investigated various types of SCD, including single-question, general memory decline, specific subjective memory decline based on a list of questions and three types of subjective naming, orientation, and calculation decline.

Results: In a single general question about memory decline, 28.0% responded positively. The percentage of our sample that reported at least one complaint related to subjective memory decline was 76.6%. Naming difficulties were also fairly common (26.0%), while specific deficits in orientation (5.4%) and calculations/currency handling (2.6%) were rare. The majority (84.2%) of the population reported subjective deficits in at least one cognitive domain. Genetic predisposition to dementia increased the odds for general memory decline by more than 1.7 times. For each one-unit reduction in the neuropsychological composite score (a mean of memory, executive, language, visuospatial, and attention-speed composite scores), the odds for decline in orientation increased by 40.3%. Depression/anxiety and increased cerebrovascular risk were risk factors for almost all SCD types.

Conclusions: SCD regarding memory is more frequent than non-memory decline in the cognitively normal Greek elderly population. Genetic predisposition to dementia, lower cognitive performance, affective symptoms, and increased cerebrovascular risk are associated with prevalent SCD. Further prospective research is needed to improve understanding of the evolution of SCD over time.