Age and dementia effect on neuropsychological test performance in very oldage - influence of risk factors for dementia

In old age a large part of the variance in cognitive performance in populat ion samples is explained by normal aging; in addition many subjects over 80 years are demented and therefore dementia also explains a part of cognitiv e variability. The question is whether the different factors for dementia ( such as ApoE4, external atrophy parameter of the cranial computer tomograph y [cCT], education, sex or serum zinc level) influence the relation between age or dementia and Mini Mental. State (MMSE) performance. In an epidemiol ogical study data were analyzed of N = 239 subjects for the above factors. Most statistically significant variables of the MMSE do not change the amou nt of the partial correlation coefficient between the parameters age or dem entia and MMSE. The external atrophy, however, diminishes the magnitude of the partial correlation between age and MMSE. In contrast the dementia-MMSE relation is unchanged. This points to a generally similar factor structure of cognitive aging and dementia in old age, but differences exist with res pect to the importance of the external atrophy parameter of the brain. Most factors investigated explain separate parts of variance of cognitive perfo rmance in old age.