Outcomes of stable and unstable patterns of subjective cognitive decline – results from the Leipzig Longitudinal Study of the Aged (LEILA75+)

Abstract

BackgroundSubjective cognitive decline (SCD), i.e., the self-perceived feeling of worsening cognitive function, may be the first notable syndrome of preclinical Alzheimer’s disease and other dementias. However, not all individuals with SCD progress. Stability of SCD, i.e., repeated reports of SCD, could contribute to identify individuals at risk, as stable SCD may more likely reflect the continuous neurodegenerative process of Alzheimer’s and other dementias.MethodsCox regression analyses were used to assess the association between stability of SCD and progression to MCI and dementia in data derived from the population-based Leipzig Longitudinal Study of the Aged (LEILA75+).ResultsOf 453 cognitively unimpaired individuals with a mean age of 80.5 years (SD = 4.2), 139 (30.7 %) reported SCD at baseline. Over the study period (M = 4.8 years, SD = 2.2), 84 (18.5 %) individuals had stable SCD, 195 (43.1 %) unstable SCD and 174 (38.4 %) never reported SCD. Stable SCD was associated with increased risk of progression to MCI and dementia (unadjusted HR = 1.8, 95 % CI = 1.2–2.6; p < .01), whereas unstable SCD yielded a decreased progression risk (unadjusted HR = 0.5, 95 % CI = 0.4–0.7; p < .001) compared to no SCD. When adjusted for baseline cognitive functioning, progression risk in individuals with stable SCD was significantly increased in comparison to individuals with unstable SCD, but not compared to individuals without SCD.ConclusionsOur results, though preliminary, suggest that stable SCD, i.e., repeated reports of SCD, may yield an increased risk of progression to MCI and dementia compared to unstable SCD. Baseline cognitive scores, though within a normal range, seem to be a driver of progression in stable SCD. Future research is warranted to investigate whether stability could hold as a SCD research feature.

Trajectories of subjective cognitive decline, and the risk of mild cognitive impairment and dementia

“…The findings are consistent with recent literature on the relevance of longitudinal assessment of SCD in identifying individuals at high risk of neurocognitive disorders. In particular, the presence of Persistent SCD over time has consistently been highlighted in recent literature as a key predictor of incident neurocognitive disorders [ 44 – 46 ]. This finding is understandable, given that neurocognitive disorders are conceptualized as progressive neurodegenerative diseases, and hence in the face of progressive neuropathological processes, individuals are more likely to experience persistent rather than transient symptoms of SCD [ 43 , 44 ].…”

“…This finding is understandable, given that neurocognitive disorders are conceptualized as progressive neurodegenerative diseases, and hence in the face of progressive neuropathological processes, individuals are more likely to experience persistent rather than transient symptoms of SCD [ 43 , 44 ]. In contrast, the evidence on the relevance of Intermittent SCD was more conflicting in the literature, with one study showing no association with incident neurocognitive disorders [ 44 ], another study showing significant association only with informant-reports and not self-reports of SCD [ 45 ], while yet another study showing significant association but in the negative direction (i.e., presence of Intermittent SCD was associated with a lower risk of neurocognitive disorders) [ 46 ].…”

“…As shown in this study, Transient SCD can still be relevant, but primarily in the older population and not among the younger individuals. It is possible that in the younger population and in lower-risk individuals (such as in community samples) [ 47 , 48 ], the association between Transient SCD and neurocognitive disorders may be diluted by many other non-neurodegenerative causes such as psychiatric conditions, personality traits, negative self-beliefs, excessive self-attention, and distressing life events [ 43 – 46 , 49 ]. Possibly, the association between Transient SCD and neurocognitive disorders may only become more apparent when these other non-neurodegenerative causes can be clearly filtered out, such as in the previous study [ 45 ], when the Transient SCD is reported by informant rather than self (and hence we may possibly filter out pure psychiatric or emotional causes that can influence an individual’s subjective reporting of cognitive decline), or such as in the current study, when most of the participants voluntarily visited the ADC to participate in longitudinal studies on cognition (which may have filtered out those without any concerns about cognition) [ 47 – 49 ] and when the Transient SCD is reported in older rather than younger age (which may have identified those with higher likelihood of neurodegenerative rather than non-neurodegenerative causes of SCD) [ 1 , 49 ].…”

“…Such single question may not be as sensitive as multi-item questionnaires in identifying the presence of anxiety symptoms. Fifth, inasmuch as this study adjusted for many covariates in the statistical models (such as depressive and anxiety symptoms), there are still other potential confounders (such as personality traits and distressing life events) [ 44 – 46 , 49 ] that were not captured in the National Alzheimer’s Coordinating Center database and hence could not be adjusted for in this study. Sixth, the diagnoses of MCI and dementia were made by single clinicians in 30.3% of the participants.…”

Functional Cognitive Disorder: Diagnostic Challenges and Future Directions

“…Other studies of the long-term prognosis of SCD have identified a variety of potential clinical trajectories, including symptom remittance. Those with persistent symptoms reported over a number of time points appear to be at greater risk of progression to MCI or dementia, whilst those who intermittently report cognitive symptoms are not at increased risk, compared to people who have never reported cognitive symptoms [18]. Clearly, in the instances of SCD and MCI, diagnostic status is often a dynamic concept.…”