or behavioral measures, but during a divided attention task, they showed increased
activation in specific brain regions—left medial temporal lobe, bilateral thalamus,
posterior cingulate, and caudate (Rodda et al. 2011 ). As in middle-aged adults,
thesefindings suggest that those with SMC may be working harder to obtain the
same level of performance and that SMC may reflect an awareness of subtle
changes in brain function.
Advances in neuroimaging also allow for direct assessments of biomarkers related
to Alzheimer’s disease, including beta amyloid. Amariglio et al. ( 2012 ) examined this
biomarker using PET with Pittsburgh compound B (PiB-PET) in relation to cognitive
complaints in 131 cognitively normal older individuals (mean age 73.5±6). Results
revealed a significant relationship between subjective memory complaints and cor-
tical PiB binding, even after controlling for depressive symptoms. Higher cortical PiB
binding suggests greater Alzheimer’s pathology, so these data suggest that SMC in
healthy older adults may be an early indicator of Alzheimer’s disease.
Fig. 13.3 Hippocampal volume and gray matter density by group. Age- and intracranial
volume-adjusted means (±SE) for manually segmented left and right hippocampi are shown in the
top row. Age-adjusted gray matter densities for the hippocampi are shown in thebottom row.HC
healthy controls,CCindividuals with cognitive complaints, andMCIindividuals with mild
cognitive impairment. Reproduced with the permission from Saykin et al. ( 2006 )
13 Subjective Memory Complaints and Objective Memory Performance 287