Hypo-perfusion and hyper-resistance affect different cognitive functions

Cognitive impairment and dementia are conventionally categorised according to their causative disease, such as Alzheimer's disease and cerebrovascular disease. Cognitive impairments of different aetiologies often share pathological cerebral blood circulation patterns, characterised by perfusion and resistance. Here, we show that these two features are associated with distinct types of cognitive impairment. Using carotid ultrasonography, we evaluated the circulation status of individuals with little to no subjective cognitive symptoms. We assessed individuals’ cognitive status using the Frontal Assessment Battery for executive function and Mini-Mental State Examination for learning and memory. Regression analysis showed that the hyper-resistance and hypo-perfusion components predicted the Frontal Assessment Battery and Mini Mental State Examination scores, respectively. These results are consistent with previous findings of hyper-resistance being associated with atherosclerosis, which disproportionately affects the frontal lobe and contributes to executive function impairments; meanwhile, hypo-perfusion disproportionately affects temporal lobe functions associated with learning and memory. We propose a novel concept that cognitive impairments fall into two subtypes regardless of the brain disease: hyper-resistance and hypo-perfusion subtypes. As these subtypes can be measured noninvasively and are treatable, this distinction would help design preventive and therapeutic strategies for dementia.