Renin‐angiotensin system blockers affect cognitive decline and serum adipocytokines in Alzheimer's disease

Abstract

BACKGROUND: Accumulating evidence indicates an association of Alzheimer's disease (AD) with the metabolic syndrome (MetS), characterized by visceral fat accumulation with insulin resistance and altered secretion of adipocytokines such as adiponectin and leptin. The renin-angiotensin system (RAS) regulates blood pressure and insulin resistance. Recent studies suggest that the RAS plays crucial roles in cognitive functions and that adipocytokines exert neuroprotective activity in the brain. We investigated whether RAS blockers (RASB) affect adipocytokines and cognitive function in patients with AD. METHODS: We studied 78 patients with a diagnosis of probable AD according to the Diagnostic and Statistical Manual of Mental Disorders, 4th edition and 106 nondemented control subjects who visited our clinic with a main complaint of headache or dizziness. We examined retrospectively the effects of RASB on adipocytokines and cognitive decline in patients with AD who were divided into three groups: hypertension treated with RASB (HT-RASB; n = 17), hypertension treated with other antihypertensive drugs (HT-other; n = 34), and no hypertension (non-HT; n = 27). RESULTS: The HT-RASB group had a significantly higher serum leptin level and a relatively larger visceral fat area than the other groups, because of the bias toward patients with MetS in this group. The HT-RASB group also had a significantly lower immunoreactive insulin level, a relatively low homeostasis model assessment as an index of insulin resistance, and a relatively high serum adiponectin level among the three groups. Cognitive decline, estimated on the basis of the mean annual decline using the Hasegawa Dementia Scale score was significantly low in the HT-RASB group. CONCLUSION: Treatment with RASB might modulate serum adipocytokines and glucose homeostasis, potentially slowing cognitive decline in patients with AD.