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, a study has found. High blood pressure and diabetes are other health problems linked to brain shrinkage and mental decline. The study is published in Neurology, the medical journal of the American Academy of Neurology.

Brain shrinkage, or cerebral atrophy as called in medical terms, is the loss of cells in brain. It can lead to a decrease of the functions controlled by that area of the brain. If the cerebral hemispheres (the two lobes of the brain that form the cerebrum) are affected, conscious thought and voluntary processes may be impaired. Slowly the brain starts losing volume, to develop lesions secondary to presumed vascular injury. The condition is such that it affects its ability to plan and make decisions as quickly as 10 years later.

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.

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.

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

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