Abstract
Subjective cognitive decline (SCD) has been proposed as a risk factor for future cognitive decline and dementia. Given the heterogeneity of SCD and the lack of consensus about how to classify this condition, different operationalization approaches still need to be compared. In this study, we used the same sample of individuals to compare different SCD operationalization approaches. We included 399 cognitively healthy individuals from a community-based cohort. SCD was assessed through nine questions about memory and non-memory subjective complaints. We applied four approaches to operationalize SCD: two hypothesis-driven approaches and two data-driven approaches. We characterized the resulting groups from each operationalization approach using multivariate methods on comprehensive demographic, clinical, cognitive, and neuroimaging data. We identified two main phenotypes: an amnestic phenotype characterized by an Alzheimer’s Disease (AD) signature pattern of brain atrophy; and an anomic phenotype, which was mainly related to cerebrovascular pathology. Furthermore, language complaints other than naming helped to identify a subgroup with subclinical cognitive impairment and difficulties in activities of daily living. This subgroup also showed an AD signature pattern of atrophy. The identification of SCD phenotypes, characterized by different syndromic and biomarker profiles, varies depending on the operationalization approach used. In this study we discuss how these findings may be used in clinical practice and research.
Highlights
Subjective cognitive decline (SCD) has been proposed as a risk factor for future cognitive decline and dementia
Individuals were selected according to the basic criteria from the research framework for SCD1: (a) normal age, gender, and education-adjusted performance on extensive neuropsychological testing according to clinical normative data; (b) normal performance in activities of daily living and global cognition defined in this study by a score ≤ 4 on the Blessed Dementia Rating Scale (BDRS)[12], a score ≤ 5 on the Functional Activity Questionnaire (FAQ)[13], and a score ≥ 26 on the Mini-Mental State Examination (MMSE)[14]; (c) absence of mild cognitive impairment (MCI) or dementia; (d) and absence of past or present psychiatric or neurologic diseases, medical disorders, substance abuse, or use of medications that might explain the presence of subjective cognitive complaints
To increase the sensitivity of this approach towards early stages of neurodegenerative diseases, we aimed to identify complaints predicting lower performance in cognitive variables that are strongly associated with measures of activities of daily living (ADL)
Summary
Subjective cognitive decline (SCD) has been proposed as a risk factor for future cognitive decline and dementia. Given the heterogeneity of SCD and the lack of consensus about how to classify this condition, different operationalization approaches still need to be compared. We used the same sample of individuals to compare different SCD operationalization approaches. Language complaints other than naming helped to identify a subgroup with subclinical cognitive impairment and difficulties in activities of daily living. This subgroup showed an AD signature pattern of atrophy. The field still lacks data on which is the best way to operationalize SCD, and the SCD-I has recently called for studies that compare different operationalization approaches of S CD3. An option is operationalizing SCD subtypes based on the frequency and distribution of cognitive complaints. Do you find it harder to recognize familiar faces or people you do not see often?
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