Regional cerebral blood flow reductions, heart failure and Alzheimer's disease

Objectives: To discuss whether there are similarities between the functional brain abnormalities detectable in association with the diagnoses of heart failure (HF) and Alzheimer's disease ( AD), focusing particularly on neuroimaging findings in vivo. Methods: Using an electronic database (Medline), we reviewed imaging studies that have evaluated resting cerebral blood flow (CBF), resting glucose metabolism or amyloid deposition in groups of subjects suffering AD or HF compared with healthy controls. Results: Single photon emission computed tomography ( SPECT) investigations have reported global CBF reductions in HF groups compared with controls. In one recent SPECT study using modern voxel-based methods for image analysis, regional CBF deficits in the pre-cuneus and posterior cingulate gyrus were detected in a sample of HF sufferers relative to controls. The regional distribution of functional deficits in the latter study was similar to that found in many positron emission tomography ( PET) investigations of glucose metabolism at early AD stages, as well as in recent PET investigations of amyloid deposition in AD. Discussion: Imaging studies have rarely investigated whether there are localized functional brain deficits in association with HF. Recent regional CBF SPECT data provide preliminary anatomic support to a view that AD-like brain changes may develop in HF patients, possibly as a consequence of chronic CBF reductions. Additional studies of larger HF samples are needed to confirm this possibility, preferably using PET measures that have afforded greater sensitivity and specificity to identify brain functional abnormalities associated with the diagnosis of AD, such as indices of glucose metabolism and amyloid deposition.