Brain Shrinkage Linked to Smoking, Obesity, Diabetes

Aug. 1, 2011 -- People who smoke, are overweight, and have other health problems in middle age may be at increased risk of developing signs of brain shrinkage and diminished planning and organization skills as they age, new research indicates.

Other health problems linked to brain shrinkage and mental decline include high blood pressure and diabetes.

“Our findings provide evidence that identifying these risk factors early in people of middle age could be useful in screening people for at-risk dementia and encouraging people to make changes to their lifestyle before it’s too late,” Charles DeCarli, MD, of the University of California-Davis in Sacramento, says in a news release.

Lifestyle Changes May Ward Off Dementia

The study involved 1,352 people who did not have dementia and whose average age was 54. They took standard tests to determine if they were overweight, had high blood pressure, diabetes, and unhealthy cholesterol levels.

In addition, each underwent MRI brain scans over the period of a decade, with the first of such tests starting about seven years after the initial examinations to detect risk factors.

Study participants with high blood pressure developed a condition in the brain known as white matter change, or small areas of blood vessel damage, faster than people with normal blood pressure readings. As they aged, they also scored lower on tests of planning and decision-making than participants with normal blood pressure.

Participants with diabetes in middle age lost brain volume at a faster pace than people without the disease.

Smoking Likely to Reduce Brain Volume

And smokers lost brain volume overall at a faster rate than nonsmokers. The smokers also were more likely to have a rapid increase in brain white matter changes, according to the researchers.

Obese people at middle age were more likely to be in the top 25% of those with the faster rate of decline in planning and decision-making skills. And participants with a high waist-to-hip ratio were more likely to be in the top 25% of those with faster decrease in their brain volume.

The researchers write that previous studies have suggested that exposure to risk factors such as high blood pressure, diabetes, and smoking during middle age seems associated with an increased risk of dementia.

Thus, studying the impact of these risk factors could help scientists better understand the mechanisms that increase the risk of dementia in some people.

And they say that modifying the risk factors during middle age may reduce the odds of people developing dementia as they get older.

Most authors disclosed financial support from research organizations or publications. DeCarli, who is editor-in-chief of Alzheimer Disease and Associated Disorders, also receives financial support from Takeda Pharmaceutical Co. Ltd., Avanir Pharmaceuticals, and Merck Serono.

The study is published in the Aug. 2, issue of Neurology, the medical journal of the American Academy of Neurology.