Abstract and Introduction
Introduction: Subjective cognitive decline (SCD) is an established precursor of dementia. However, the relationship between SCD and dementia has been mostly studied among people aged 65+. We aimed to assess the association between subjective memory difficulties at ages 50–75 with all-cause dementia and dementia-subtypes in a community-based cohort with long-term follow-up.
Methods: 6,190 individuals (51% female) aged 50–75 years (median age, 62) attending a general health examination (by a total of 684 general practitioners) in Saarland, Germany, in 2000–2002 were recruited for a community-based cohort study. Subjective difficulties regarding short-term and long-term memory were assessed at baseline with two simple yes/no questions. Associations with dementia (–subtypes) diagnoses during 17 years of follow-up were estimated by Cox proportional hazards models.
Results: 492 participants were diagnosed with dementia during 17 years of follow-up. Participants with short-term memory difficulties were at higher risk to receive incident all-cause dementia and vascular dementia diagnoses both within 0–9 years (age and sex adjusted hazard ratios (aHR), 1.80 and 2.00, respectively) and within 0–17 years (aHR 1.55 and 1.78, respectively) from recruitment (P < 0.05 in all cases). For clinical Alzheimer's disease, a significant association was only seen within the initial 6 years. There were no associations of long-term memory difficulties with any type of dementia.
Conclusions: Subjective difficulties in short-term memory predict both intermediate and long-term risk of vascular and all-cause dementia even among late middle-age adults. These results underline the importance of cardiovascular disease prevention efforts well before old age for maintaining cognitive health.
Dementia is one of the most prevalent neurodegenerative diseases and is a rapidly growing public health burden. Studies have shown that 80% of people worry about developing dementia and report it frequently as their most feared illness,[2,3] underlining the importance of increased efforts in effective prevention.
Subjective cognitive decline (SCD) might be a very early indicator of cognitive impairment and can be considered a precursor of dementia.[4,5] SCD is defined as the self-report on perceived cognitive decline in memory or cognitive domains such as executive function in the absence of objective memory impairment. It is frequently assessed by questions about the worsening of memory and whether or not the decline worries the person.[6–8]
Prevalence of SCD has been reported to be around 25% in older adults with annual conversion rates to mild cognitive impairment and dementia of about 7 and 2%, respectively.[9,10] Across various studies and follow-up times strong associations between SCD and Alzheimer's disease (AD) and non-AD dementia have been reported among participants aged 65+ to 75+.[8,11,12] Interestingly, the risk of dementia for participants with SCD seems to be lower in community-based settings compared to memory-clinic settings. Generally, there is a scarcity of studies assessing the association of subjective memory difficulties and dementia among late middle-age adults (i.e. 50 years or older), in particular in community settings and in cohort studies with long-term follow-up.
To provide further insight in this area of research, we assessed subjective short and long-term memory difficulties through two simple questions at baseline in a community-based cohort study of participants aged 50 years and older that were then followed for up to 17 years. The main aim of this study was to investigate the association of baseline subjective short-term and long-term memory difficulties with risk of incident all-cause dementia, clinical AD, vascular dementia and mixed dementia diagnoses within 17 years. The secondary aim was to conduct stratified analyses according to age at baseline (50–64, 65–69 and 70+ years) and baseline depression status.
Age Ageing. 2022;51(6):afac113 © 2022 Oxford University Press
Copyright 2007 British Geriatrics Society. Published by Oxford University Press. All rights reserved.