Obesity and Dementia
A study in the British Journal of Medicine (reference 16) attempts to determine the relationship between being overweight and obese in mid-life, and the risk of dementia in later life. The study tracked 10,000 men and women aged 40 to 45, who underwent detailed health evaluations. Approximately 30 years later, 713 of the participants were diagnosed with dementia. After correcting for various other factors, such as hypertension, diabetes, heart disease, etc., the study finds that being obese significantly increases one's chances of getting dementia, especially in women. For all participants, being obese in mid-life increases the risk of dementia later in life by a Risk Ratio of 1.74 (Margin of Error between 1.34 and 2.26). For women, the numbers are 2.07 (1.49 to 2.89). For men, the Risk Ratio is 1.30 (0.84 to 1.20) - this actually implies that men may not have an increased risk of dementia, since the Margin of Error includes unity (1.00).
For overweight people (regardless of sex), the risk ratio is 1.35 (Margin of Error between 1.14 to 1.60). For women, the numbers are 1.55 (1.22 to 1.97), and for men - 1.16 (0.91 to 1.46).
When the researchers use the thickness of skinfold, rather than BMI as a measure of obesity, the results for men become more conclusive. The study divides the participants into quintiles, based on their skinfold thickness under the shoulder. Women in the highest quintile of skinfold thickness have an increased risk: 1.52 (1.11 to 2.08), as do men:1.97 (1.36 to 2.85).
The study leaves little doubt that obesity in mid-life does lead to an increased risk in dementia later in life, although the Margin of Error is significant. There are also indications that being overweight (but not obese) increases the risk for dementia, especially in women. This should be considered one more reason to be careful about putting on extra pounds...