Sex and Cognitive Status Independently Affect Hippocampal and Cortical Lobar Cerebral Blood Flow in Nondemented Older Adults

Separate literatures have shown that cerebral blood flow decreases across the Alzheimer’s disease spectrum and is lower in males relative to females, at least within cortical gray matter. However, no known studies have tested for an interaction between the effects of cognitive status and sex on cerebral blood flow, as may be expected if blood flow contributes to the greater risk of developing mild cognitive impairment (MCI) for females. Moreover, sex differences in cerebral blood flow have not been examined in the hippocampus, which is known to be affect in MCI and Alzheimer’s disease. Therefore, the current study examined effects of cognitive status, sex, and their interaction on cerebral blood flow in the cortical lobes and hippocampus in 111 cognitively unimpaired older adults (CU) and 49 older adults diagnosed with MCI from the Alzheimer’s Disease Neuroimaging Initiative (ADNI3) with T1-weighted and perfusion- weighted magnetic resonance imaging data. As expected, cerebral blood flow across all cortical lobes was significantly lower in MCI relative to CU older adults and in males relative to females. In contrast, cerebral blood flow in the hippocampus was significantly lower in females relative to males and there was no effect of cognitive status. There were also no significant interactions between cognitive status and sex in any region of interest. Taken together, these findings indicate that effects of sex on cerebral blood flow are region specific and independent of cognitive status in non-demented older adults.