The relationships between arterial hypertension and cognitive decline are complex and studies indicate controversial results.
Objectives: To evaluate, in a cross sectional study, the relationships between cognitive functions and blood pressure in a population of subjects with Alzheimer's disease.
Methods: In 520 subjects of a survey in a French population with Alzheimer's disease, relationships between the severity of cognitive decline and a history of hypertension or blood pressure level have been searched. Cognitive functioning was assessed with validated neuropsychological tests evaluating cognitive functions and the capacities in the activities of daily living (Mini Mental State Examination (MMSE), Alzheimer's Disease Assessment Scale--Cognitive part (ADAS-Cog), Instrumental Activities of Daily Living (IADL), Activities of Daily Living (ADL), Clinical Dementia Rating (CDR), Global Deterioration Scale (GDS) of Reisberg). In 456 subjects blood pressure was measured during the consultation.
Results: The results indicate that after adjustment on age, sex, education level, and the other cardiovascular risk factors, subjects with a history of hypertension have a more marked cognitive decline than subjects without history of hypertension. Indeed, in subjects with a history of hypertension, the cognitive impairment and its consequences on activities of daily living are more important than in subjects without history of hypertension (ADAS-cog 19.02 +/- 8.48 vs 17.49 +/- 8.53 p = 0.06, MMSE 19.55 +/- 4.41 vs 20.30 +/- 4.42, p = 0.08, score ADL 5.31 +/- 0.86 vs 5.51 +/- 0.87, p = 0.01, CDR 6.94 +/- 3.29 vs 6.19 +/- 3.26 p = 0.03; global CDR 1.18 +/- 0.62 vs 1.05 +/- 0.60, p = 0.03, GDS of Reisberg 4.41 +/- 0.74 vs 4.27 +/- 0.75, p = 0.05). In contrast, no relation between blood pressure measurements and cognitive function is observed, and moreover an inverse correlation between blood pressure and consequences on activities of daily living is found.
Conclusions: This work indicates that relationships between blood pressure and cognitive functions are more complex than a simple linear relation. The present results show that a history of arterial hypertension is associated with a more marked cognitive decline in subjects with Alzheimer's disease. In contrast, when the Alzheimer's disease is already developed no relation between blood pressure and cognitive functions appears and moreover an inverse correlation with the consequences on activities of daily living is found.