BMJ  2005;331:455 (20 August), doi:10.1136/bmj.331.7514.455

Letter

Obesity in middle age and future risk of dementia

Midlife obesity increases risk of future dementia

EDITOR—Whitmer et al reported a prospective study showing that obesity in middle age was associated with increased risk of future dementia.¹ However, little information was given on the types of dementia. This is important especially in Alzheimer's disease, in which vascular risk factors might contribute to its development.² We have investigated the relation between Alzheimer's disease and obesity throughout adult life in a small case-control study.

We recruited 25 patients with probable Alzheimer's disease from the Launceston Memory Disorders Clinic, Tasmania, and 50 controls from the local community. Patients were living at home and were physically well, with no important medical problems. Current height, weight, and waist circumference were measured. In addition, we asked participants to recall their weight at the age of 20-25 and 40-45. Self reported weight has been shown to be highly correlated with direct measurement in cognitively healthy people and those with mild to moderate dementia.^{3 4}

The mean age of patients with Alzheimer's disease and controls was 74.9 (range 57-88) and 72.1 (65-94), respectively. The mean mini-mental state examination score was 19.0 (4-26) for patients with Alzheimer's disease and 29.6 (28-30) for controls. Most patients had mild to moderate disease (80% with scores greater than 14). The table shows that at midlife, patients with Alzheimer's disease had higher body mass index (BMI) by 2.8 kg/m² or 12% than controls. At late life, BMI was not significantly different, but the waist circumference in patients with Alzheimer's disease was higher than in controls by 6.1 cm, or 7%.

View this table: [in this window] [in a new window]   Means (standard errors) and logistic regression odds ratios (per standard deviation) for BMI and waist circumference, adjusted for age, sex, years of education, cigarette smoking, and alcohol consumption

 

Our study supports the conclusion of Whitmer et al that midlife obesity increases the risk of future dementia, in this case Alzheimer's disease. In addition, abdominal obesity, which is highly associated with insulin resistance and cardiovascular diseases, might also be a risk factor for Alzheimer's disease.

george.razay{at}dhhs.tas.gov.au
Launceston General Hospital, Launceston, Tasmania 7250, Australia

Launceston General Hospital, Launceston, Tasmania 7250, Australia

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Competing interests: None declared.

References

1. Whitmer RA, Gunderson EP, Barrett-Connor E, Quesenberry CP, Yaffe K. Obesity in middle age and future risk of dementia: a 27 year longitudinal population based study. BMJ 2005;330: 1360-2. (11 June.)[Abstract/Free Full Text]
2. Skoog I, Kalaria RN, Breteler MM. Vascular factors and Alzheimer disease. Alzheimer Dis Assoc Disord 1999;13(suppl 3): S106-114.
3. Payette H, Kergoat MJ, Shatenstein B, Boutier V, Nadon S. Validity of self-reported height and weight estimates in cognitively-intact and impaired elderly individuals. J Nutr Health Aging 2000;4: 223-8.[Medline]
4. Must A, Willett WC, Dietz WH. Remote recall of childhood height, weight and body build by elderly subjects. Am J Epidemiol 1993;138: 56-64.[Abstract/Free Full Text]

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Relevant Article

Obesity in middle age and future risk of dementia: a 27 year longitudinal population based study

Rachel A Whitmer, Erica P Gunderson, Elizabeth Barrett-Connor, Charles P Quesenberry, Jr, and Kristine Yaffe
BMJ 2005 330: 1360. [Abstract] [Full Text] [PDF]