Cerebral Blood Flow and Cognition. Clinical studies on Dementia and Cognitive Decline

Abstract: The importance of early detection of brain changes during ageing has been recognised. Single photon emission computed tomography (SPECT) is a method used for estimation of cerebral blood flow (CBF) in clinical work and in research. The aim of thesis was to study CBF in demented and non-demented elderly persons with special reference to blood pressure changes. Elderly women with senile dementia of Alzheimer type (SDAT) showed a decrease of CBF in temporoparietal brain regions and in whole white matter. Non-demented elderly women had abnormalities according to SPECT and assessment with vocabulary and visospatial tests. CBF in white matter was correlated positively with systolic blood pressure in SDAT group. It cannot be ruled out, that alterations in blood pressure in SDAT could have a central origin and be the consequence rather than cause of brain changes. Women with SDAT and orthostatic hypotension had lower CBF in frontal and parieto-frontal regions than SDAT patients who had normal orthostatic blood pressure. Orthostatic hypotension could be a risk factor for a frontal brain damage and exacerbate the dementia disorder. Intra-subject comparison of CBF estimated with two tracers in healthy subject revealed higher perfusion in posterior cortex when using 99mTc ECD compared to 99mTc HMPAO. In contrast, CBF in central areas was seen to be more profuse when using 99mTc HMPAO. These differences should be taken into account in clinical routine. In another study, persons with Age-Associated Memory Impairment but without dementia had restricted CBF in temporal and occipital lobes, in thalamus and in frontal white matter. A longitudinal study of 129 men revealed an association between accumulated vascular disease markers as: carotid stenosis, peripheral arterial stenosis and hypertension at the age of 69 and lower CBF 14 years later. These results indicate that there might be a potential for prophylactic activities to prevent cognitive decline and vascular dementia in non-demented 70-80 year old population