Asymmetric Cerebral Blood Flow in Patients with Mild Cognitive Impairment: Possible Relationship to Further Cognitive Deterioration

Abstract

Aim: To explore patterns of cerebral blood flow in patients with mild cognitive impairment (MCI), who (1) eventually deteriorate into overt dementia, with no particular focus on the type of dementia, or (2) do not appear to further deteriorate in their cognitive functions. Methods: Thirty-seven MCI patients, with or without vascular pathology, were studied prospectively. The patients underwent ^99mTc-HMPAO SPECT analysis at baseline. Possible clinical conversion into dementia within a 2-year period was assessed. Results: Nineteen patients had progressive MCI (PMCI), while 18 patients were considered clinically stable (SMCI). PMCI patients had more often abnormally low cerebral blood flow in at least one of the frontal, temporal, parietal or occipital lobes compared to SMCI patients (12/19 vs. 5/18; p = 0.049). At least one of the temporal regions was found to be abnormal in 9 PMCI patients in contrast to only 1 SMCI patient (p = 0.008). More specifically, blood flow in the medial portion of the left temporal region was abnormal in 8 PMCI patients, a pattern seen in 1 SMCI patient only (p = 0.019). Conclusion: The results suggest that blood flow reductions particularly in the left medial temporal region indicate an elevated risk of further cognitive decline in MCI patients.