Study Finds 4 Modifiable Risk Factors Explain Most Dementia Cases

A recent study of Japanese-American men, published in the Journal of the American Geriatrics Society last month, has found that just four modifiable risk factors could explain the majority of dementia cases.

The study involved 3,468 middle aged men from the Honolulu-Asia Aging Study who were followed up over 25 years. The researchers theorized that a healthy lifestyle in mid-life could reduce an individuals probability of developing dementia in their later years.

Dr. Rebecca P. Gelber, and colleagues looked at four lifestyle characteristics that had been associated that dementia risk in previous studies. The factors were BMI, smoking, physical activity, and diet. The low risk group for BMI was defined as a BMI < 25, the low risk group for smoking was defined as former or non-smokers. For physical activity low risk was defined as being in the top 25% for hours spent doing light or moderate physical activity per day. The low risk diet consisted of relatively low meat and dairy consumption, high consumption of fish, cereals, fruits and vegetables, a high monounsaturated-to-saturated fat ratio, and light to moderate consumption of alcohol. Over the course of the study, 223 of the participants developed dementia, including 117 cases of Alzheimer's Disease, and 78 cases of vascular dementia. BMI was the strongest risk factor for dementia with a BMI > 25 increasing the odds of developing dementia by 87%. Current smokers had 48% increased odds of developing dementia while individuals with low physical activity had 59% increased odds of developing the disease. Interestingly diet was not strongly correlated with dementia risk in this study.

As a general rule, the lifestyle factors predicted vascular dementia risk better than Alzheimer’s disease risk. For example, a BMI > 25 resulted in a 2.29-fold increase in the odds of vascular dementia but only 1.51 times increased odds of developing Alzheimer’s disease.

Interestingly, individuals who were low risk for all four factors had just 0.36 times the risk of developing dementia compared to other men in the study suggested that a large percentage of dementias could be avoided through a healthy lifestyle in middle age. Men in all four low risk groups comprised just 7.2% of all men in the study.

Vascular dementia and Alzheimer’s disease are the two most common forms of dementia. Vascular dementia occurs when the supply of blood to the brain is restricted. Vascular dementia and cardiovascular disease have similar risk factors and the two diseases often go hand in hand because the cardiovascular system is responsible for delivering blood to the brain.