Cross-sectional and longitudinal characterization of SCD patients recruited from the community versus from a memory clinic: subjective cognitive decline, psychoaffective factors, cognitive performances, and atrophy progression over time

Abstract

Background Subjective cognitive decline (SCD) defines a heterogeneous population, part of which having Alzheimer’s disease (AD). We aimed at characterizing SCD populations according to whether or not they referred to a memory clinic, by assessing the factors associated with increased AD risk. Methods Seventy-eight cognitively unimpaired older adults from the IMAP+ study (Caen) were included, amongst which 28 healthy controls (HC) and 50 SCD recruited from the community (SCD-community; n = 23) or from a memory clinic (SCD-clinic; n = 27). Participants underwent cognitive, psychoaffective, structural MRI, FDG-PET, and amyloid-PET assessments. They were followed up over a mean period of 2.4 ± 0.8 years. The groups were compared in terms of baseline and follow-up levels of SCD (self- and informant-reported), cognition, subclinical anxiety and depression, and atrophy progression over time. We also investigated SCD substrates within each SCD group through the correlations between self-reported SCD and other psychometric and brain measures. Results Compared to HC, both SCD groups showed similar cognitive performances but higher informant-reported SCD and anxiety. Compared to SCD-community, SCD-clinic showed higher informant-reported SCD, depression score, and atrophy progression over time but similar brain amyloid load. A significant increase over time was found for depression in the SCD-community and for self-reported praxis-domestic activities SCD factor in the SCD-clinic. Higher self-reported SCD correlated with (i) lower grey matter volume and higher anxiety in SCD-community, (ii) greater informant-reported SCD in SCD-clinic, and (iii) lower glucose metabolism in both SCD groups. Conclusions Higher subclinical depression and informant-reported SCD specifically characterize the SCD group that refers to a memory clinic. The same group appears as a frailer population than SCD-community as they show greater atrophy progression over time. Yet, both the SCD groups were quite similar otherwise including for brain amyloid load and the SCD-community showed increased depression score over time. Altogether, our findings highlight the relevance of assessing psychoaffective factors and informant-reported SCD in SCD populations and point to both differences and similarities in SCD populations referring or not to a memory clinic. Electronic supplementary material The online version of this article (10.1186/s13195-019-0514-z) contains supplementary material, which is available to authorized users.

Clinical meaningfulness of subtle cognitive decline on longitudinal testing in preclinical AD

“…Finally, the reported link between an individual's own cognitive concerns (rather than those of an informant) and AD biomarkers in asymptomatic individuals suggests that there may be additive utility in examining trajectories of cognitive complaints alongside cognitive decline to predict risk for clinical progression . This may also be extended to measures of mild neurobehavioral changes as well as potentially novel measures of health outcomes developed in coordination with patient and caregivers to better identify what is of value from an individual's perspective (e.g., driving, perceived competence, etc).…”

“…Finally, the reported link between an individual's own cognitive concerns (rather than those of an informant) and AD biomarkers in asymptomatic individuals 26 suggests that there may be additive utility in examining trajectories of cognitive complaints alongside cognitive decline to predict risk for clinical progression. 27 This may also be extended to measures of mild neurobehavioral changes [28][29][30]…”

Functional neuroimaging in subjective cognitive decline: current status and a research path forward

“…Perhaps individuals who are concerned about their cognitive ability and seek medical advice represent older adults with SCD more likely to harbor incipient neurodegeneration while individuals recruited from the general public may include SCD cases in an early disease phase, or cases due to neuroticism, poor sleep, or transient stressful life events. The extant literature suggests that recruitment methods may indeed contribute to SCD sample characteristics, with cohorts recruited from memory clinics exhibiting poorer neuropsychological performance, greater hippocampal atrophy, greater cortical atrophy over time, and greater depression than cohorts recruited from the general population that have not sought medical help [93][94][95]. However, as samples that have sought medical help have exhibited both increased and decreased functional connectivity cross-sectionally [18,30,47], the impact of the severity of cognitive complaint on functional metrics is not as clear.…”

Structural and Functional Hippocampal Changes in Subjective Cognitive Decline From the Community

“…In addition, studies have suggested that the recruitment sources for SCD studies may have a significant influence on study outcomes. For instance Kuhn et al (2019) found higher atrophy progression over time and a relatively smaller proportion of APOE ε4 carriers in patients from an SCD clinic compared SCD patients from the community. This finding reinforced their previous study, which found that those who seek consultation are at a higher risk of developing Alzheimer's clinical syndrome (Perrotin et al, 2017).…”

“…It indicated that SCD-clinic patients may constitute a more vulnerable population than SCD-community patients. They may be at increased risk for cognitive decline and possibly Alzheimer's clinical syndrome (Kuhn et al, 2019).…”