Amyloid-β Imaging in Older Adults Presenting to a Memory Clinic with Subjective Cognitive Decline: A Pilot Study

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.

To test whether 'presenting SCD' participants in an academic memory clinic setting show increased brain Aβ deposition on imaging.

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).

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.

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.