Mild cognitive impairment: prevalence and predictive validity according to current approaches

Objectives - Mild cognitive impairment is associated with an increased risk of developing dementia. However, there is no consensus on diagnostic criteria and different concepts have rarely been evaluated in population-based samples. This paper compares the prevalences and predictive validities for different concepts in a population-based study. The aim was to identify a concept with the best relation of sensitivity and specificity in the prediction of dementia. Material and methods - A community sample of 1045 dementia-free individuals aged 75 years and over was examined by neuropsychological testing in a three-wave longitudinal study. Prevalence rates ranged from 3 to 36% according to the concept applied. Conversion rates to dementia over 2.6 years ranged from 23 to 47%. In addition, receiver operating characteristic curves indicated that all but one concept for mild cognitive impairment could predict dementia. Conclusion - Mild cognitive impairment is very frequent in older people. Prevalences and predictive validities are highly dependent on the diagnostic criteria applied.