Abstract
Background: Subjective cognitive decline (SCD) in otherwise normal aging may
be identified via symptom inventories in a research setting (‘questionnaire-discovered
complaints’) or via patients seeking evaluation/services in a clinical setting
(‘presenting complainers’). Most studies of SCD and amyloid-β (Aβ) imaging to date have
used the former approach, with inconsistent results.
Objective: To test whether ‘presenting SCD’ participants in an academic
memory clinic setting show increased brain Aβ deposition on imaging.
Methods: Fourteen patients (mean age 68.1, SD 4.0 years) diagnosed with
subjective cognitive complaints with normal neuropsychological testing were recruited into
a Pittsburgh compound B (PiB)-PET study. Detailed self-report inventories and additional
cognitive tests were administered. Results were compared to a reference cohort of
cognitively normal volunteers (NC) from an independent neuroimaging study (mean age 73.6,
SD 5.8 years).
Results: 57% (8/14) of SCD participants were PiB-positive by a sensitive,
regionally-based definition, compared to 31% (26/84) of the NC cohort. SCD participants
had significantly higher PiB retention (SUVR) than NC in three of six regions of interest:
frontal cortex (p = 0.02), lateral temporal cortex
(p = 0.02), and parietal cortex (p = 0.04). SCD
participants showed measurable deviations on questionnaires reflecting high negative
affect (i.e., depressive symptoms and neuroticism). Findings were suggestive that deficits
on verbal associative binding may be specific to Aβ-positive versus Aβ-negative SCD.
Conclusion: Older participants with SCD presenting to a memory clinic in this
pilot study sample have higher brain Aβ deposition compared to normal aging study
volunteers unselected on complaints. Further study of presenting SCD are warranted to
determine the prognostic significance of Aβ deposition in this context.
