Neuropsychological Function in Relation to Structural and Functional Brain Changes in Alzheimer’s Disease

Previously published papers have been reproduced with permission from the copyright holders. ….we don´t always remember that we forgot, so that to remember that we forgot is not exactly forgetting, is it? What I loved by Siri Hustvedt SUMMARY Neuropsychological Functions in Relation to Structural and Functional Brain Changes in Alzheimer's Disease. The aim of this doctoral thesis was to study neuropsychological functions in relation to structural and functional brain changes in mild to moderate Alzheimer´s disease (AD). In the first study relations between hippocampal volume, neuropsychological function and limbic-hypothalamic-pituitary-adrenal (LHPA) axis disturbances in AD were investigated. Hippocampal volume was measured with magnetic resonance imaging (MRI). Reduced hippocampal CA1 volume and suppressed cortisol levels in combination, best predicted the variation in neuropsychological performance. The conclusion was that reduced hippocampal volume and LHPA axis disturbances are associated with level of cognitive function in AD. The second study focused on whether patients with mild to moderate AD showed an altered regional cerebral bloodflow (rCBF) pattern compared to healthy elderly. Correlation between performance on memory tests and rCBF in sub-lobar volumes of the brain were investigated. The rCBF was measured with single photon emission computed tomography (SPECT). AD patients showed a significantly lower rCBF in temporoparietal regions including left hippocampus compared to controls. The diagnostic sensitivity and specificity for AD was high in temporoparietal regions. AD patients had significantly lower performance on semantic and in particular episodic memory tests compared to the controls. Their performance on several episodic tests correlated with rCBF in parietal and temporal regions including the left hippocampus suggesting that abnormalities in the rCBF pattern underlie impaired episodic memory functioning in AD. The conclusion was that an observer-independent analyzing method for SPECT with sub-lobar volumes of interest (VOI) is promising in the diagnosis of AD. In a third study possible differences in memory-related functional brain activation between persons with high versus low risk for AD were examined with functional magnetic resonance imaging (fMRI). The high-risk individuals performed worse than low-risk individuals on tests of episodic memory. Patterns of brain activity during episodic encoding and retrieval showed significant group differences. During both encoding and retrieval, the low-risk persons showed increased activity relative to a baseline condition in prefrontal and hippocampal brain regions that previously have been implicated in episodic memory. In contrast, the high-risk persons did not significantly activate any prefrontal region, but instead showed increased activity in visual occipito-temporal regions. …