The study involved 10,276 members of Kaiser Permanente medical care programme in California who underwent detailed health checks from 1964 to 1973 when they were aged 40-45 and who were still members of the health plan in 1994.
Information was collected on demographics, medical history, medical conditions, body mass index, and skinfold thickness in the subscapular (shoulder) and tricep (back of the upper arm) area.
In 1994, dementia was diagnosed in 713 (7%) participants. Obese people (body mass index 30 or above) were 74% more likely to have dementia, while overweight people (body mass index 25-29.9) were 35% more likely to have dementia compared with those of normal weight (body mass index 18.6-24.9).
Body mass index predicted dementia more strongly among women. For example, obese women were 200% more likely to have dementia than women of normal weight, while obese men had a non-significant 30% increase in risk.
Both men and women with the highest skinfold measurements had a 60-70% greater risk of dementia compared to those with the lowest measurements.
There were no significant race interactions between body mass index and risk of dementia.
Obesity and overweight in middle age is strongly associated with an increased risk of dementia in old age, regardless of the presence of existing illnesses in mid and late life, say the authors.
Obesity and overweight in middle age is strongly associated with an increased risk of dementia in old age, regardless of the presence of cardiovascular disease and diabetes in mid and late life, say the authors.
To date, this is the first study to determine the contribution of mid-life adiposity and skinfold thickness on risk of dementia, they add. If these results can be confirmed elsewhere, perhaps treatment of obesity might reduce the risk of dem
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BMJ-British Medical Journal
28-Apr-2005