Deterioration of visual-perceptual organization ability in Alzheimer's disease.

Although deterioration of higher-order visual information processing abilities occurs in Alzheimer's disease (AD), few cross-sectional or longitudinal studies have systematically examined this deficit. The performance of 135 patients with probable AD and 97 matched normal control (NC) participants were compared on a structured test of perceptual organization ability, the Hooper Visual Organization Test (VOT). Both the standard VOT score and a derived score that corrected for anomia were significantly lower for AD patients than for NC participants, but neither score was particularly effective at distinguishing between the groups. The derived VOT score proved to be a more effective measure of visuospatial functioning than the standard VOT score as it loaded with other visuospatial tests in a principal components analysis while the standard score loaded with language tests. The VOT was sensitive to severity of dementia in the AD patients. Longitudinal assessment of 37 of the AD patients and 46 NC participants revealed significant decline over one year in the VOT scores of AD patients, but not in those of NC participants. These results indicate that higher-order visual information processing is impaired in patients with AD and gradually deteriorates with disease progression. This deficit may not be a particularly salient early marker of the disease, but it may be useful in tracking disease course.

The clock drawing test as a measure of executive dysfunction in elderly depressed patients.

The aims of this research were to determine whether performance on the Clock Drawing Test (CDT) could accurately distinguish between older patients with depression and older patients with depression and previously undocumented executive dysfunction and to determine if there was a correlation between CDT and depression severity. The authors studied 52 patients consecutively admitted to a geriatric psychiatry inpatient unit of a university hospital who met DSM-IV criteria for major depression or depression not otherwise specified but had no concurrent diagnosis of dementia. All the subjects completed the Mini-Mental State Examination (MMSE), Mattis Dementia Rating Scale (DRS), and the CDT, as well as the Geriatric Depression Scale (GDS). The patients were divided into 2 subgroups based on the DRS score: <129 (cognitive impairment) versus = 129. Results indicated that the depressed patients with a score of DRS <129 had significantly lower CDT scores than did patients with DRS = 129 and normal comparison subjects (P< .01). The results support the hypothesis that CDT score is lower in elderly depressed patients with executive dysfunction versus nondepressed seniors as well as depressed patients without executive dysfunction.