Subjective Cognitive Decline as a predictor of Frailty in older adults: Hellenic Longitudinal Investigation of Aging and Diet study (HELIAD).

Background: Subjective cognitive decline (SCD) is a self-evaluation of cognitive impairment, in the absence of observed objective cognitive deficits on a neuropsychological assessment. Frailty refers to a multidimensional syndrome where the individual has poor health including falls, disabilities, hospitalization, and vulnerability. Both terms are associated with cognitive decline and increased incidence of dementia. The present longitudinal study explored whether the detection of SCD can predict the development of frailty over time.

Methods: The Hellenic Longitudinal Investigation of Aging and Diet (HELIAD) is an epidemiological, population-based study. From the original testing sample of 1,984 older Greek individuals (≥65 years old), 1,121 remained in the longitudinal analysis. Participants diagnosed with frailty, Mild Cognitive Impairment (MCI), dementia, severe depression, and anxiety, in the baseline assessment were excluded from the analysis (n=146), resulting in a total sample of 975 participants. The average follow-up interval was 3.1 years (SD=0.84 years). SCD was assessed in the baseline assessment with a series of eighteen questions. The questions regarding SCD were categorized according to cognitive domains. Frailty was assessed according to a phenotypic-physiologic (Fried's definition) and a multidomain approach (Frailty Index). Univariate and multivariate Cox regression analyses were used for exploring the role of SCD in developing frailty.

Results: The proportion of individuals with frailty according to Fried's definition was greater compared to the Frailty Index. At follow-up according to Fried's definition, a greater proportion of cases with frailty was found in those who reported SCD complaints regarding orientation (OD) (HR=3.12 95% CI:1.45-6.73 p<0.004) or in those who reported at least three SCD complaints regarding their memory performance (SMC3) (HR=1.92 95% CI:1.05-3.52 p<0.035) at the baseline assessment. Subjective complaints regarding orientation were predictive of a greater hazard of frailty as defined by the Fried scale (HR=3.12 95% CI:1.45-6.73 p<0.004) and the Frailty Index (HR=3.59 95% CI:1.77-7.25 p<0.001).

Conclusion: Our findings demonstrate that healthy older adults who report SCD complaints regarding orientation or state that they have at least three memory complaints have a higher risk of developing frailty. Additionally, the number of participants with a clinical diagnosis of MCI or dementia, compared to individuals with normal aging, at follow-up was found to be significantly greater in cases with frailty according to both frailty definitions applied (p<0.001). Consequently, it is advisable to use screening questionnaires for SCD covering multiple cognitive domains in clinical practice for identifying and managing frailty, thus, implementing effective interventions to promote healthy aging.