P2-228: Cerebral perfusion in Alzheimer's disease using dynamic susceptibility contrast MRI

Abstract

groups according to the presence of visual hallucination; seven DLB patients with visual hallucination and 6 patients without visual hallucination. No differences between patient with and without visual hallucination was found in their cognitive function measured by mini mental status exam (MMSE) and clinical dementia rating (CDR) scale. Regional metabolic differences on FDG PET among the groups were tested using SPM. Results: We found diffuse glucose hypometabolism in the entire cortex including the occipital region seems to be a typical feature of DLB that is distinctive from dementia of Alzheimer’s disease.In DLB patients groups regardless of visual hallucination, significant regional hypometabolism were observed in the bilateral occipital cortices as well as bilateral parietotemporal and frontal association cortices when compared with healthy controls, as expected. In DLB patients with visual hallucination compared to patients without hallucination, regional hypometabolism over primary and secondary visual cortex (BA17, BA18) was more significant. Moreover, lower regional metabolism in the paracentral area (BA 6) and cerebellar vermis was also observed in DLB with visual hallucination than without hallucination. Conclusions: This characteristic pattern of cortical hypometabolism including the occipital areas could be a result of diaschisis due to disruption of intracortical connections. Diaschisis is defined as depression of regional neuronal metabolism and cerebral blood flow caused by dysfunction in anatomically separate but functionally related neuronal regions.We propose that the limitation that occipital hypometabolism may be manifested not only in DLB. Profound hypometabolism in the visual cortex may be a feature in DLB patients with visual hallucination. Also, relative hypometabolism in the paracentral area and cerebellum could be neurobiological characteristics related with abnormal cognitive and motor process response to hallucination