Being obese at age 50 may be associated with an increased risk of developing Alzheimer's disease at a younger age. Previous studies have shown that being overweight at midlife is associated with an increased risk of developing Alzheimer's, but there was no information on whether excess body weight was linked to a person's age at the onset of the disease or to its severity. A new study has found that excess weight may be linked to onset of Alzheimer's at a younger age.
Researchers used information gathered by a prospective study, the Baltimore Longitudinal Study of Aging. They studied 1,394 cognitively normal people who had an average age of 60. These people were followed for an average of nearly 14 years. Their body mass index (BMI) was based on their weight at age 50.
During the course of the study, 142 of them developed Alzheimer's disease. In addition, 191 people in the study were autopsied after they died and assessed for neurological disease. Seventy-five participants who did not have dementia underwent brain imaging to look for amyloid, a substance in the brain that is linked with Alzheimer's.
The study found that for each unit increase in BMI at age 50 there was a 6.7-month decrease in the age of onset of Alzheimer's disease. This was found even after controlling for age, race, level of education, and cardiovascular risk factors in the people in the study.
The study also found an association of higher BMI with larger deposits of neurofibrillary tangles, one of the anatomical characteristics of brain changes in Alzheimer's disease, seen on autopsy.
Being overweight in midlife predicts an earlier onset of Alzheimer's disease and a greater burden of Alzheimer's changes in the brain, the study concluded. "A health BMI at midlife may delay the onset of [Alzheimer's disease]."
The study was published in the journal Molecular Psychiatry.