Abstract
Subjective cognitive decline, a perceived worsening of cognitive functioning without objective deficit on assessment, could indicate incipient dementia. However, the neural correlates of subjective cognitive decline as assessed by magnetic resonance imaging remain somewhat unclear. Here, we evaluated differences in functional connectivity across memory regions, and cognitive performance, between healthy older adults aged 50 to 85 with (n = 35, Age = 68.5 ± 7.7, 22 female), and without (n = 48, Age = 67.0 ± 8.8, 29 female) subjective cognitive decline. We also evaluated neurite density, fractional anisotropy, and mean diffusivity of the parahippocampal cingulum, cingulate gyrus cingulum, and uncinate fiber bundles in a subsample of participants (n = 37). Participants with subjective cognitive decline displayed lower average functional connectivity across regions of a putative posterior memory system, and lower retrosplenial-precuneus functional connectivity specifically, than those without memory complaints. Furthermore, participants with subjective cognitive decline performed poorer than controls on visual working memory. However, groups did not differ in cingulum or uncinate diffusion measures. Our results show differences in functional connectivity and visual working memory in participants with subjective cognitive decline that could indicate potential incipient dementia.
Highlights
Subjective cognitive decline (SCD) is a putative, preclinical stage of Alzheimer's disease marked by perceived deterioration in cognitive functioning, in any domain, without overt deficit (Jessen et al, 2014a)
Participants with SCD did not differ in Apolipoprotein E (APOE) ε4 prevalence compared to those without, p 1⁄4
Individuals with SCD had higher Geriatric Depression Scale scores, t(80) 1⁄4 À2.34, p 1⁄4 .02; they were significantly more likely to answer “Yes” to a question directly related to memory functioning (“Do you feel you have more problems with memory than most?”), p
Summary
Subjective cognitive decline (SCD) is a putative, preclinical stage of Alzheimer's disease marked by perceived deterioration in cognitive functioning, in any domain, without overt deficit (Jessen et al, 2014a). Associations between self-perception of cognitive functioning and objective cognitive deficits are complex (Mitchell, 2008). Individuals may experience worrisome subjective decline in memory ability, but test within a normal range on neuropsychological assessment. Taken together, these notions diminish the predictive power of cognitive complaints alone, or the lack thereof, for determining current dementia status. Evidence indicates that these cognitive complaints are predictive of future decline and may demarcate incipient dementia that precedes mild cognitive impairment (Gifford et al, 2014; Jessen et al, 2010, 2014b; Reisberg et al, 2008, 2010)
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