Hypertension and incident dementia in community-dwelling elderly Yoruba Nigerians

OBJECTIVES: To investigate the relationship between hypertension and dementia incidence in community-dwelling elderly Yoruba (aged 70 years and above) because of sparse information on dementia and its risk factors in developing countries. MATERIALS AND METHODS: Community-based, prospective study of consenting elderly Yoruba using two-stage design. Blood pressure was measured during the baseline evaluation at 2001 and hypertension was defined as BP ≥ 140/90 mmHg. Diagnosis of dementia and normal cognition was by consensus using standard criteria. Non-demented subjects from the 2001 evaluation wave were re-evaluated during the 2004 and 2007 waves for dementia. Logistic regression was used to examine the association of baseline hypertension and incident dementia, after adjusting for age, gender, education, and histories of stroke and smoking. P-values <0.05 were considered significant. RESULTS: During the 6-year follow-up, 120 individuals developed dementia, while 1633 remained non-demented. The frequency of hypertension in the demented group was significantly higher than in the non-demented (70.0% vs 60.2%, P = 0.034). Baseline hypertension was a significant risk factor for dementia (OR = 1.52; 95% CI 1.01-2.30). Higher systolic, diastolic or pulse pressure was associated with increased risk (P < 0.05). Participants with diastolic BP ≥ 90 mmHg were at a significantly greater risk than those with readings below 70 mmHg (OR = 1.65; 95% CI 1.01-2.69). CONCLUSIONS: Hypertension was associated with increased risk of dementia in elderly Yoruba and its appropriate treatment may lower the risk.