Twin study: Diabetes significantly increases risk for Alzheimer's disease and other dementia

Jan 27, 2009

Diabetics have a significantly greater risk of dementia, both Alzheimer's disease — the most common form of dementia — and other dementia, reveals important new data from an ongoing study of twins. The risk of dementia is especially strong if the onset of diabetes occurs in middle age, according to the study.

"Our results . . . highlighted the need to maintain a healthy lifestyle during adulthood in order to reduce the risk of dementia late in life," explained Dr. Margaret Gatz, who directs the Study of Dementia in Swedish Twins.

In a study published in the January 2009 issue of Diabetes, Gatz and researchers from Sweden show that getting diabetes before the age of 65 corresponds to a 125 percent increased risk for Alzheimer's disease. Nearly 21 million people in the United States have diabetes, according to the American Diabetes Association, which publishes the journal.

This risk of Alzheimer's disease or other dementia was significant for mid-life diabetics — as opposed to those who develop diabetes after 65 — even when controlling for family factors. In other studies, genetic factors and childhood poverty have been shown to independently contribute to the risk of both diabetes and dementia.

"Twins provide naturally matched pairs, in which confounding factors such as genetics and childhood environment may be removed when comparisons are made between twins," explained Gatz, professor of psychology, gerontology and preventive medicine at the University of Southern California and foreign adjunct professor of medical epidemiology and biostatistics at the Karolinska Institute in Sweden.

Indeed, the chances of a diabetic developing Alzheimer's disease may be even greater in real life than in the study, the researchers write. They identify several factors that might have led them to underestimate the risk of dementia and Alzheimer's among those who develop diabetes before the age of 65.

Diabetes usually appears at a younger age than dementia does, the researchers note. Diabetes is also associated with a higher mortality rate, which may reduce the size of the sample of older adults. In addition, approximately 30 percent of older adults with diabetes have not been diagnosed.

The results of the study implicate adult choices such as exercise, diet and smoking, as well as glycemic control in patients with diabetes, in affecting risk for Alzheimer's disease and diabetes, according to the researchers.

The sample for the study was 13,693 Swedish twins aged 65 or older in 1998, the year tracking for dementia began. Information about diabetes came from prior surveys of twins and linkage to hospital discharge registry data beginning in the 1960s.

Reference: Weili Xu, et al., "Mid- and Late-Life Diabetes in Relation to the Risk of Dementia." Diabetes: January 2009.

Source: University of Southern California

Explore further: Research shows that bacteria survive longer in contact lens cleaning solution than thought

add to favorites email to friend print save as pdf

Related Stories

More evidence links diabetes to Alzheimer's risk

Mar 16, 2009

(AP) -- You've heard that diabetes hurts your heart, your eyes, your kidneys. New research indicates a more ominous link: That diabetes increases the risk of getting Alzheimer's disease and may speed dementia once it strikes.

Study shows elderly drivers support competency tests

May 25, 2011

Researchers studying driving habits and accident rates among the elderly found a majority surveyed supported mandatory retesting of drivers based on age while saying they would hand over the keys if a doctor or loved one ...

Recommended for you

Ebola virus in Africa outbreak is a new strain

9 hours ago

The Ebola virus that has killed scores of people in Guinea this year is a new strain—evidence that the disease did not spread there from outbreaks in some other African nations, scientists report.

Researchers see hospitalization records as additional tool

10 hours ago

Comparing hospitalization records with data reported to local boards of health presents a more accurate way to monitor how well communities track disease outbreaks, according to a paper published April 16 in the journal PLOS ON ...

User comments : 0

More news stories

New clinical trial launched for advance lung cancer

Cancer Research UK is partnering with pharmaceutical companies AstraZeneca and Pfizer to create a pioneering clinical trial for patients with advanced lung cancer – marking a new era of research into personalised medicines ...

More vets turn to prosthetics to help legless pets

A 9-month-old boxer pup named Duncan barreled down a beach in Oregon, running full tilt on soft sand into YouTube history and showing more than 4 million viewers that he can revel in a good romp despite lacking ...