Neuropsychological correlates of cerebral atrophy in Alzheimer's dementia

Abstract

This study aims to systematically analyze the relationship between neuropsychological deficits and regional cerebral atrophic changes in Alzheimer's dementia (AD). As an extension of previous studies we not only investigated substructures of the medial temporal lobe but also included other relevant cerebral regions such as frontal, temporal, and parietal lobes. This approach was based on the assumption that morphological correlates of global and specific cognitive dysfunction might reflect to a certain degree the neuronal basis of the respective function. Accordingly, the functional role assigned to a certain cerebral structure or region can be further elucidated which might lead to a better understanding of the clinical and neuropsychological heterogeneity of AD. Fifty patients with AD (NINCDS-ADRDA criteria) and 20 healthy elderly control subjects were included. All patients and controls were examined on a standardized neuropsychological test battery. In addition, magnetic resonance imaging (MRI) of the brain was performed. Volumes of the whole brain, CSF-spaces, amygdala-hippocampus complex, frontal lobes, temporal lobes, and parietal lobes were measured using a standardized protocol. AD-patients were characterized by neuropsychological deficits with respect to memory, language, praxia, cognitive speed as well as attention and concentration. These deficits were differentially correlated with regional atrophic changes. In particular, volumes of the right amygdala-hippocampus complex were correlated with declarative memory performance in the non-verbal visual domain. Furthermore, an association between left temporo-parietal regions and aspects of semantic memory, as well as verbal recall and left frontal regions could be established. The validity of our results is supported by recent findings from neuropathological and functional neuroimaging studies. In conclusion, our data indicate that MRI-based volumetry can be successfully used to detect morphological correlates of neuropsychological heterogeneity in AD and that this methodological approach allows to fruitfully study the neuronal basis of cognitive functions.