Morphometric changes in the cortical microvascular network in Alzheimer's disease.

Alzheimer's disease (AD) pathology is accompanied by abnormalities of the microvasculature. Despite the potential importance of morphometric changes in the cortical capillary network on neuronal dysfunction and cognitive impairment, few autopsy studies have addressed this issue. In the present study, we investigated morphological microvascular changes and capillary length density (CLD) in ten well-characterized AD patients compared to ten age-matched controls using virtual isotropic hemispheres. The CLD in the temporal cortex was increased by 33% in AD patients compared to controls (p=0.04), whereas CLD in the occipital cortex was unchanged. An increase of CLD was correlated to a decrease of cortical diameter in the temporal cortex (Pearson's r -0.62, p=0.003), suggesting that the increase in temporal CLD results from, or contributes to cortical atrophy. In the occipital cortex, more string vessels, probably remnants of degenerated capillaries, were observed in AD patients than in controls (p=0.004). An exploratory analysis suggests co-localization of Aβ and string vessels. Our data indicate that morphometric changes in the cortical capillary network occur in AD in a region-specific manner and may be related to cortical atrophy in the affected regions.