Background and Objectives Subjective cognitive decline (SCD) is a common experience of self-perceived decline without objective cognitive impairment among older adults. SCD has been conceptualized as very early Alzheimer’s disease (AD), but the specific SCD features predictive of clinical or cognitive decline remain unclear. This systematic review is the first to characterize specific SCD features and their relation to longitudinal outcomes. Research Design and Methods Multiple electronic databases were searched from inception until August 2021 for longitudinal studies of adults aged >50 (mean>60) and free of dementia, with baseline SCD measurement and clinical or cognitive follow-up. Studies were screened for inclusion criteria and assessed for risk of bias using weight-of-evidence ratings. Results 570 potentially relevant studies were identified, and 52 studies evaluated for eligibility after initial screening. Thirty-three studies with medium to high weight-of-evidence ratings were included and results narratively synthesized. Measurement methods varied substantially across studies: the majority (n=27) assessed SCD symptom types and intensity, and consistently reported that higher symptom burden increased the risk for MCI and dementia. The evidence was less compelling for cognitive outcomes. A handful of studies (n=5) suggested a predictive role for SCD symptom consistency and informant corroboration. Discussion and Implications SCD symptom intensity emerged from our review as the most reliable predictor of future clinical outcomes. Combinations of SCD-Plus symptoms also had predictive utility. No single symptom was uniquely prognostic. Our findings support the quantitative evaluation of SCD symptoms in the assessment of risk for progression to MCI or dementia.

BackgroundSubjective Cognitive Decline (SCD) refers to a self‐experienced decline in cognitive capacity despite normal performance on objective tests. Research has consistently linked SCD to incident Alzheimer’s disease (AD). The role of perceptions around aging and AD risk in the SCD experience has not been clearly delineated. Here we aimed to determine the association between chronological age, self‐perceived risk for AD, and SCD symptom burden.MethodCommunity‐dwelling participants aged ≥50 years (n = 483), located within the United States were recruited via the crowdsourcing website Amazon Mechanical Turk. They completed a survey consisting of demographic questions and the Subjective Cognitive Decline Questionnaire (SCD‐Q MyCog). The survey also included items about self‐perceived risk for AD (“Do you believe that you are at higher risk of AD than your peers”; endorsed = 1, not endorsed = 0) and an AD family history (endorsed = 1; not endorsed = 0). Linear regression was used to predict SCD total score from combinations of these measures, adjusted for gender.ResultThe sample’s descriptive data were: age M = 64±5.5, range 50–79, SCD total M = 4.7±5.8, range 0–24, 66.5% female. There were 17% (n = 82) who perceived themselves at heightened risk for AD, and 27% (n = 132) with a positive family history. When entered together, high perceived risk predicted higher SCD total whereas family history and age were not predictive: B = 4.9, p<.001, B = ‐.004, p = .99, B = ‐.024, p = .59, respectively, R‐squared = .11. SCD total was M = 8.8±6.6 for the high‐risk, 3.9±5.2 for low‐risk group. Adding age squared did not improve the model: B = ‐.001, p = .88. Interaction analyses revealed a trend for perceived AD risk but not family history to be conditional on age, B = ‐.260, p = .067, B = .060, p = .603..Johnson‐Neyman regions‐of‐significance indicated that beyond age 70, the coefficient for self‐perceived AD risk approached zero and was non‐significant:ConclusionOur findings highlight the importance of self‐perceptions of AD risk for SCD in the youngest old adults (age<70). These individuals appear to evaluate their cognitive capacity in relation to their perceived susceptibility to AD. Interestingly, objective risk (older age, AD family history) does not contribute to this evaluation.

Background Subjective Cognitive Decline (SCD) designates a self‐experienced worsening of cognition before that decline becomes detectable by objective cognitive assessment. SCD has been examined as an early stage of Alzheimer’s disease (AD), but the evidence linking self‐reported SCD features to clinical progression is inconsistent and the predictive validity of SCD presence and symptom burden remains uncertain. More nuanced measures of SCD which differentiate between domains of cognitive decline are needed. This study examined SCD across the domains of Memory, Language and Executive function to identify a pattern of decline associated with well‐established risk factors for AD: family history of AD, female gender, and older age. Method Community‐dwelling participants aged >50 years (M age=64, n=483) were recruited via the crowdsourcing website Amazon Mechanical Turk and completed a survey including demographic questions and the Subjective Cognitive Decline Questionnaire (SCD‐Q MyCog). Risk factors were binary (family history yes/no, female/male, age <70/=>70). Multivariate analysis of variance (MANOVA) was then performed for each risk factor grouping, with the three domains of SCD serving as dependent variables. Follow‐up discriminant analysis was performed on significant relationships Result The sample included 27% of participants with a positive family history, 66.5% female, and 14.5% aged >70 years. Those with a positive family history differed on a combination of SCD domain scores from those without family history, Pillai’s trace=‐.0.023, p=.011 (Memory M=2.6 vs. 1.8, Language M=2.0 vs. 1.4, Executive Function M=1.4 vs. 1.1). No other group differences reached statistical significance. Discriminant function coefficients showed that the memory domain was the strongest contributor (0.984), followed by language (0.849), and finally executive function (0.583). Conclusion A positive family history is a reliable predictor of future AD. We found that those with a positive family history reported a greater amount of subjectively experienced memory and language decline. Memory and language concerns may be helpful in assessing risk of AD in those endorsing SCD.

Music production is a complex activity that involves nearly every function in the brain. Whether skills transfer from musical training to other cognitive abilities is a growing area of research. There is evidence to suggest that musical training in children and adult musicians is associated with an improvement in a variety of executive functions (EFs). This study examined whether those associations are also present during adolescence, and whether there is a relationship between the time spent in musical training and EF. Adolescents between the ages of 14 and 18 completed three tests of EF: Tower of Hanoi to assess working memory, Wisconsin Card Sort Test to assess cognitive flexibility, and Stroop Color Word Task to assess inhibition. They also completed a musical experience questionnaire, including their lifetime musical practice hours. Adolescent musicians were found to have improved inhibitory control (as measured by the Stroop Task) relative to nonmusicians and inhibition correlated with musical practice time. No other elements of EF were found to be associated with musical training. These findings suggest that the impact of musical training may not be the same for all EFs, and that there may be unique associations between this type of training and inhibitory control.

Subjective cognitive decline (SCD) is a construct of high interest in aging and dementia because individuals endorsing it are at higher risk of developing cognitive problems. It is unclear how individuals arrive at the judgement that they have SCD. Here we aimed to understand which SCD symptoms give rise to the perception of decline as older adults age. Community-dwelling adults (N=494, mean age=63.6, SD=5.44), completed the Subjective Cognitive Decline Questionnaire (SCD-Q) online, using an online crowdsourcing site. The SCD-Q consists of one global question regarding self-perceived decline (yes/no) and 24 questions about everyday functioning which we utilized to form a memory, language, and executive functioning domain score, higher for greater perceived decline. Logistic regression revealed that memory and language domains predicted the likelihood of endorsing SCD for adults aged &gt;64 (Memory: OR=1.76, CI=1.47-2.05; Language: OR=1.66, CI=1.30-2.02). Only the memory domain predicted the likelihood of endorsing SCD for adults &lt;63 (OR=2.69, CI=2.35-3.02). Executive functioning domain scores did not play a role in the relationship between SCD likelihood in either age group. The higher the self-perceived memory or language decline, the more likely older adults are to conclude they have SCD. Our results suggest there is an age-related trajectory in how people evaluate their cognition, with younger people only considering memory and older people considering both memory and language. Clinicians should be aware of this trajectory when examining patients with SCD. Executive functions should be specifically queried because they may not emerge from older adults’ self-reported cognitive problems.