Midlife Obesity Linked to Late-Life Dementia
If Verified, Findings Could Provide 1 More Reason to Get in Shape
April 28, 2005 -- A new long-term study shows that people who were obese or overweight in middle age had an increased risk of dementia later in life.
"Obesity and overweight in middle age as measured by body mass index [BMI] and skinfold thickness were strongly associated with risk of dementia in later life," write researchers in a study, which appears in BMJ Online First.
"If these results can be confirmed elsewhere, perhaps treatment of obesity might reduce the risk of dementia," write the researchers, who included Rachel Whitmer, PhD, a gerontological epidemiologist with Kaiser Permanente's research division in Oakland, Calif.
Trends May Intertwine in the Future
Dementia is usually seen in older adults. The most common form is Alzheimer's disease. Other types of dementia were also included in the study.
The incidence of dementia is expected to increase by 400% in the next 20 years as the population ages, according to the study. Meanwhile, obesity is also on the rise in the U.S. and around the world.
"Failure to contain the present epidemic of obesity may accentuate the expected age-related increase in dementia," write Whitmer and colleagues.
Long Look at Weight, Dementia
Whitmer's study included 10,276 people who were members of Kaiser Permanente Northern California Medical Group, a health insurance plan.
Between 1964 and 1973, the men and women got detailed health evaluations including BMI and skin-fold thickness at the shoulder and at the back of the arm.
At the time, participants were 40-45 years old. They were all still members of the health plan in 1994.
From January 1994 to April 2003, 713 participants (6.9%) were diagnosed with dementia. On average, they were about 74 years old when dementia was diagnosed.
People who were obese or overweight in middle age had a higher risk of late-life dementia than those of normal weight, according to the study.
Stroke, diabetes, heart disease, high blood pressure, and high cholesterol were taken into account. So were age, sex, race, and education level. Marital status, smoking, and alcohol use in midlife were also noted.
"Obesity in middle age increases the risk of future dementia independently of comorbid conditions," researchers write.
Tracking Obesity's Effects
For those with an obese BMI (30 or higher) in middle age, the risk of dementia in old age was 74% higher than for those with normal BMI. For those who were overweight (BMI of 25-29.9), late-life dementia risk was 35% higher than those with normal BMI, the researchers report.
The skin-fold tests also showed a similar pattern.
Men with the largest skin-fold measurements in midlife had a 72% higher risk of dementia in old age than those with the smallest skin-fold measurements. Middle-aged women with the biggest skin-fold readings had a 60% increase in their risk of late-life dementia compared with those with the skinniest shoulders and arms in midlife.