NEW DELHI: People with no high BP, diabetes or smoking habit lived nearly 13 years longer without dementia than those with all three risk factors, a long-term US study has found. Those without any of the three lived an average 30 years without dementia from age 55, compared with 17.5 years among those with all three.The study, based on the US-based Atherosclerosis Risk in Communities (ARIC) Study, followed 12,409 adults for a median 26.3 years. Researchers assessed three midlife vascular risk factors: diabetes, hypertension and current smoking.Dementia-free survival fell progressively as the number of risk factors increased. Those with one risk factor had an average 26.3 dementia-free years from age 55, while those with two had 21 years. Participants with all three had 17.5 years, compared with 30.1 years among those with none.The risk of developing dementia also increased with vascular risk burden. Compared with people with none of the three risk factors, those with all three had a 2.69-fold higher hazard of developing dementia. Their hazard of dying without dementia was 5.61 times higher.The effect was particularly striking at older ages. Among people with all three risk factors, dementia risk increased from 23% at age 55 to 37% at age 75. By age 85, only 7% remained dementia-free, compared with 35% of those with no risk factors.Recently, WHO’s updated global guidelines say up to 45% of dementia risk could be prevented or delayed by tackling modifiable risk factors, including high BP, diabetes, smoking and physical inactivity. The guidelines also recommend reducing exposure to air pollution.Dr Manjari Tripathi, head of the neurology department at AIIMS, said, “It is essential to control blood pressure and blood sugar, avoid smoking and excessive alcohol, maintain a healthy weight, stay physically active and control cholesterol from midlife itself.”The researchers said the findings suggest that overall vascular health in midlife, rather than an isolated risk factor, is an important determinant of dementia-free survival.Preventing vascular risk factors by midlife could therefore help extend the number of years people live without dementia.The authors pointed to several possible biological mechanisms linking vascular health and dementia, including chronic blood-vessel damage, inflammation and oxidative stress associated with hypertension, diabetes and smoking. These processes may increase stroke risk and contribute to changes associated with Alzheimer’s.The study has limitations. Vascular risk factors were assessed at a single point in midlife, so changes in health over subsequent years were not captured. The authors said this could underestimate the impact of sustained or worsening vascular risk.
