Subjective memory complaints (SMC) are common among elderly. Although subtle changes in memory functioning can hardly be determined using neuropsychological evaluation, neuroimaging studies indicate regionally smaller brain structures in elderly with SMC. Imaging of resting-state functional connectivity is sensitive to detect changes in neurodegenerative diseases, but is currently underexplored in SMC. Here, we investigate resting-state functional connectivity and brain structure in SMC. We analyzed magnetic resonance imaging data of 25 elderly with SMC and 29 age-matched controls (mean age of 71 years). Voxel-based morphometry and volume measurements of subcortical structures were employed on the structural scans using FSL. The dual regression method was used to analyze voxel-wise functional connectivity in relation to eight well-characterized resting-state networks. Group differences were studied with two-sample t-tests (p<0.05, Family-Wise Error corrected). In addition to gray matter volume reductions (hippocampus, anterior cingulate cortex (ACC), medial prefrontal cortex, cuneus, precuneus, and precentral gyrus), elderly with SMC showed increased functional connectivity in the default mode network (hippocampus, thalamus, posterior cingulate cortex (PCC), cuneus, precuneus, and superior temporal gyrus) and the medial visual network (ACC, PCC, cuneus, and precuneus). This study is the first which demonstrates that, in addition to smaller regional brain volumes, increases in functional connectivity are present in elderly with SMC. This suggests that self-reported SMC is a reflection of objective alterations in brain function. Furthermore, our results indicate that functional imaging, in addition to structural imaging, can be a useful tool to objectively determine a difference in brain integrity in SMC.

Aging is associated with cognitive decline, diminished brain function, regional brain atrophy, and disrupted structural and functional brain connectivity. Understanding brain networks in aging is essential, as brain function depends on large-scale distributed networks. Little is known of structural covariance networks to study inter-regional gray matter anatomical associations in aging. Here, we investigate anatomical brain networks based on structural covariance of gray matter volume among 370 middle-aged to older adults of 45–85 years. For each of 370 subjects, we acquired a T1-weighted anatomical MRI scan. After segmentation of structural MRI scans, nine anatomical networks were defined based on structural covariance of gray matter volume among subjects. We analyzed associations between age and gray matter volume in anatomical networks using linear regression analyses. Age was negatively associated with gray matter volume in four anatomical networks (P < 0.001, corrected): a subcortical network, sensorimotor network, posterior cingulate network, and an anterior cingulate network. Age was not significantly associated with gray matter volume in five networks: temporal network, auditory network, and three cerebellar networks. These results were independent of gender and white matter hyperintensities. Gray matter volume decreases with age in networks containing subcortical structures, sensorimotor structures, posterior, and anterior cingulate cortices. Gray matter volume in temporal, auditory, and cerebellar networks remains relatively unaffected with advancing age.

Background and Purpose-To investigate the prognostic value of cerebral microbleeds (CMB) regarding overall, cardiovascular-related, and stroke-related mortality and to investigate possible differences based on a cerebral amyloid angiopathy-type and nonlobar distribution of microbleeds. Methods-We included 435 subjects who were participants from the nested MRI substudy of the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER). Cox proportional hazard models were applied to estimate the risk of overall, cardiovascular-related, and stroke-related death associated with microbleeds in general and microbleeds with a lobar distribution suggestive of the presence of cerebral amyloid angiopathy. The corresponding Kaplan-Meier survival curves were calculated. Results-Subjects with Ͼ1 CMB had a 6-fold risk of stroke-related death compared to subjects without CMB (hazard ratio, 5.97; 95% CI, 1.60 -22.26; Pϭ0.01). The diagnosis of nonlobar microbleeds was associated with Ͼ2-fold risk of cardiovascular death compared to subjects without microbleeds (hazard ratio, 2.67; 95% CI, 1.23-5.81; Pϭ0.01). Subjects with probable cerebral amyloid angiopathy-type microbleeds had Ͼ7-fold risk of stroke-related death compared to subjects without CMB (hazard ratio, 7.20; 95% CI, 1.44 -36.10; Pϭ0.02). Conclusions-This is the first study investigating the association between microbleeds and risk of overall, cardiovascular-related, and stroke-related mortality in an elderly population. Our findings indicate that the diagnosis of microbleeds is potentially of clinical relevance. Larger studies are needed to expand our observations and to address potential clinical implications and cost-benefits of such a policy. (Stroke. 2011;42:638-644.)