[Associations between cognitive performance in a dementia screening test (SKT) and an intelligence test (WAIS IV) : Which deficits in cognitive performance in old age indicate a possible pathological deterioration process?]

Background: Which deficits in cognitive performance indicate the onset of a pathological deterioration process in older persons?
Aim and Objectives: Based on an established dementia screening test in elderly adults, a differentiation can be made between healthy cognitive performance and the onset of pathological deficits in performance (in the sense of mild cognitive impairment). The aim of the study was to investigate whether cognitive decline assessed with a dementia screening instrument is reflected in an intelligence test for adults. The dementia screening measured disorders in memory and attention, the intelligence testing battery measured information processing, working memory, perceptual reasoning, logical thinking and verbal comprehension.
Material and Methods: A total of 253 cognitively healthy, self-dependent and non-dementia persons (129 women and 124 men), aged between 60 and 91 years (M = 71.98 years; SD = ±7.13) were tested with the complete Wechsler adult intelligence scale (WAIS-IV) and the short performance test (SKT), based on the new normalization from 2015. The SKT enables an assessment of the degree of cognitive deterioration based on coloring codes of traffic lights. Green indicates normal aging, yellow mild cognitive impairment and red stands for abnormal cognitive aging.
Results and Conclusion: There were significant correlations between the total SKT score as a measure of total cognitive impairment and the indices of the WAIS-IV, such as information processing, working memory and perceptual reasoning. No significant covariation was found for verbal comprehension. The results suggest that in old age cognitive deterioration starts with reduced speed of information processing and impairment in the working memory log before deficits in memory are present. This finding was reflected in significant mean differences between the subjects in the category green versus yellow in the indices information processing and working memory. Under these aspects there were medium effect strengths (d = 0.60) and the second largest (insignificant) differences were shown in working memory (d = 0.39).