Subjective memory concern, negative affect, and cortical microstructural integrity in community-dwelling middle-aged men.

Concerns about memory often increase with age and have been suggested as a precursor to impending memory impairment or dementia. However, subjective memory concern (SMC) has also been shown to reflect an individual's trait-like tendency to worry about memory, which is more strongly linked to negative affect than to objective memory performance. Despite behavioral evidence supporting a trait-like dimension of SMC, its neuroanatomical underpinnings remain underexplored. In 477 community-dwelling dementia-free men (56-72 years old), we investigated the association between SMC and cortical mean diffusivity (cMD)-a diffusion MRI-based metric of gray matter microstructural integrity-generating a brain-wide map of their association. Self-report trait anxiety and depressive symptoms were collected, along with objective memory scores based on three neuropsychological tasks for which brain maps of their association with cMD were also generated. Finally, we conducted spatial correlational analyses to compare the spatial patterns of these brain association maps to assess whether there were significant spatial resemblances between each. We found that the gray matter integrity correlates of SMC spatially resembled those of depressive symptoms and trait anxiety but not those of objective memory. The spatial correspondences between gray matter integrity correlates of negative affect measures and SMC were significantly stronger than those between SMC and objective memory. Together, these results suggest a neuroanatomical basis of trait-like SMC, which should be distinguished from state-related SMC that may be a precursor of objective memory deficits in research and clinical settings.