The extent and distribution of biochemical abnormalities thought to reflect disorders of subpopulations of neurons have been determined in the cerebral cortex from brains of patients with Alzheimer-type dementia and depressive illness who died of natural causes. In dementia, loss of gray matter from areas of the parietal and temporal lobes is most obvious. In depression, these areas are not affected, but the pars opercularis and temporal pole are smaller than in controls. Results expressed per unit mass of total protein indicate selective reductions in both disorders of serotonin 2 recognition sites in all areas examined and of somatostatin content in only the temporal pole of the six areas examined. In dementia alone a selective loss was found of somatostatin content of the superior parietal lobule and of serotonin 1A sites and choline acetyltransferase activity in all areas examined. Results for depression expressed per entire area indicate additionally reduced somatostatin content and serotonin 1A sites in the pars opercularis and serotonin 1A sites in the temporal pole. These multiple analyses performed on each sample provide further support for a prominent disorder of pyramidal neurons in dementia as well as more evidence for alterations in cortical neurons in depression, either as a result of the disease itself or its treatment.

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A decline in the ability to process facial expression of emotions has been reported in individuals with Alzheimer's disease (AD). However, the low number of participants and the lack of diversity in the tasks being used in previous studies leaves a gap in our knowledge about this issue. We recruited 169 participants including healthy older adults (HOA), participants with mild cognitive impairment (MCI) and AD patients at different stages of the disease (mild to moderate). Four tasks including recognition, selection, matching and declarative knowledge about facial expression of emotions were used. Face identification was used as a control task. Our results revealed that compared with HOA, MCI participants did not show any significant deficits in none of the tasks. AD patients did not show any impairment in the control task. However, they were impaired in the processing of facial expression of negative emotions across all four affective tasks. Interestingly, recognition and selection of happiness were intact in AD patients at the mild stage of the disease. Our findings suggest that despite the pathology affecting distributed areas in the brain, the less challenging aspects (recognition and selection) of the ability to process the facial expression of happiness were preserved at the early stage of the disease. By recruiting a large number of participants using several different tasks our study provides a comprehensive picture of the disorders of facial emotion processing in Alzheimer's Disease. Our findings have significant implications for improving the AD patients' quality of life and the quality of their social interaction with others. Future studies might start to investigate the processing of emotions in AD patients in other modalities rather than visual.