Background and aims: Prevalence and incidence ratios of dementia in epidemiological studies vary according to the data source used. Medical records, cognitive tests, and registry information are sources frequently used to differentiate dementia from normal aging. The aim of the present study was to compare the identification of dementia from these different sources with that from consensus diagnosis. 

Methods: 498 elderly people (age range 70–81 at baseline) enrolled in a Swedish population-based longitudinal twin study (Gender) were evaluated on physical and mental health and interviewed for their socio-demographic background three times during an eight-year period. Reviews of medical records and the Swedish Discharge Registry (DR) were conducted. The 10th percentile was used to differentiate between dementia and non-dementia in all cognitive tests. Scores of 24 or below on the Mini-Mental State Examination (MMSE) (range 1–30) indicated dementia. A consensus conference diagnosed dementia on the basis of total information. The consensus diagnosis was used as the gold standard. 

Results: MMSE scores (sensitivity 64%, specificity 96%, kappa 0.65) and the review of medical records (sensitivity 57%, specificity 99%, kappa 0.65) were good sources for dementia identification. The precision of medical records increased when recordings of cognitive impairment were included (sensitivity 83%, specificity 98%, kappa 0.84). The discharge registry had low sensitivity (26%) and kappa coefficient (0.31). 

Conclusions: The present study shows that both review of medical records and MMSE scores are good although not perfect identifiers of dementia. The discharge registry is an uncertain source of dementia identification.

BACKGROUND: Although an increasing body of evidence links being overweight in midlife with an increased risk for dementia in late life, no studies have examined the association between being overweight in midlife and cognitive ability in late life. Our aim was to examine the association between being overweight in midlife as measured by body mass index (BMI) and cognitive ability assessed over time. METHODS: Participants in the Swedish Adoption/Twin Study Aging were derived from a population-based sample. The participants completed baseline surveys in 1963 or 1973 (mean age 41.6 years, range 25-63 years). The surveys included questions about height, weight, diseases, and lifestyle factors. Beginning in 1986, the same individuals were assessed on neuropsychological tests every 3 years (except in 1995) until 2002. During the study period, 781 individuals who were 50 years and older (60% women) had at least one complete neuropsychological assessment. A composite score of general cognitive ability was derived from the cognitive test battery for each measurement occasion. RESULTS: Latent growth curve models adjusted for twinness showed that persons with higher midlife BMI scores had significantly lower general cognitive ability and significantly steeper longitudinal decline than their thinner counterparts. The association did not change substantially when persons who developed dementia during the study period were excluded from the analysis. CONCLUSIONS: Higher midlife BMI scores precede lower general cognitive ability and steeper cognitive decline in both men and women. The association does not seem to be mediated by an increased risk for dementia

OBJECTIVES: To describe the association between body mass index (BMI) and dementia risk in older persons.

DESIGN: Prospective population‐based study, with 8 years of follow‐up.

SETTING: The municipality of Lieto, Finland, 1990/91 and 1998/99.

PARTICIPANTS: Six hundred five men and women without dementia aged 65 to 92 at baseline (mean age 70.8).

MEASUREMENTS: Weight and height were measured at baseline and at the 8‐year follow‐up. Dementia was clinically assessed according to Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria.

RESULTS: Eighty‐six persons were diagnosed with dementia. Cox regression analyses, adjusted for age, sex, education, cardiovascular diseases, smoking, and alcohol use, indicated that, for each unit increase in BMI score, the risk of dementia decreased 8% (hazard ratio (HR)=0.92, 95% confidence interval (CI)=0.87–0.97). This association remained significant when individuals who developed dementia early during the first 4 years of follow‐up were excluded from the analyses (HR=0.93, 95% CI=0.86–0.99). Women with high BMI scores had a lower dementia risk (HR=0.90, 95% CI=0.84–0.96). Men with high BMI scores also tended to have a lower dementia risk, although the association did not reach significance (HR=0.95, 95% CI=0.84–1.07).

CONCLUSION: Older persons with higher BMI scores have less dementia risk than their counterparts with lower BMI scores. High BMI scores in late life should not necessarily be considered to be a risk factor for dementia.