Developing Diabetes before Age 65 Increases Risk of Alzheimer's Disease

A new study has found that diabetics, especially people who develop the disease before age 65, are at a significantly higher risk of developing both Alzheimer’s disease and other forms of dementia.

Margaret Gatz, PhD, professor of psychology, gerontology and preventive medicine at USC, and foreign adjunct professor of medical epidemiology and biostatistics at the Karolinska Institute in Sweden, and colleagues examined more than 13,500 Swedish twins during the study. They found that getting diabetes before 65 was linked to a 125 percent increased risk for Alzheimer’s disease.

The chance of developing this serious form of dementia was significantly higher in earlier-onset diabetics when compared to people who developed diabetes after age 65, even when controlling for family factors. In previous studies, genetic factors and childhood poverty had been shown to separately contribute to the risk of diabetes and dementia.

“Twins provide naturally matched pairs, in which co-founding factors such as genetics and childhood environment may be removed when comparisons are made between twins,” said Gatz.

The researchers said that the results of the study point to adult choices, such as exercise, diet, and smoking, as contributing to the risk for Alzheimer’s disease as well as diabetes.

“Our results... highlighted the need to maintain a healthy lifestyle during adulthood in order to reduce the risk of dementia late in life,” said Gatz.

The study authors also noted that the chance of a diabetic developing Alzheimer’s disease could actually be much greater in real life than in the study. Since diabetes is associated with a higher mortality rate, the size of the sample of older adults could be impacted. Also, according to the researchers, 30 percent of older adults with diabetes have not been diagnosed.