No abstract

This study examined the ability of neurologically healthy individuals and individuals with Alzheimer’s disease (AD) to successfully complete procedures involving short-term spatial visuomotor memory tasks, and tasks involving increasingly complex visuomotor transformations. Participants made sliding finger movements over a clear touch-sensitive screen on two separate spatial planes (vertical and horizontal), to visually constant and remembered target positions. Significant main effects were observed between participant groups on reaction time and movement time measures. As well, significant changes in reaction time and movement time were observed within the patient group over the different of any experimental procedures. In addition, as task increased in complexity significant increases in errors were observed in the AD group. Overall, the results reveal that AD patients show substantial declines in their ability to process and integrate visual information to produce motor responses. Therefore, we believe that this psychophysical research provides further evidence that AD, even early stages of AD, can affect anatomical regions supporting vision for action.

This study investigated the role of visuospatial tasks in identifying cognitive decline in patients with Alzheimer's disease (AD), by correlating neuropsychological performance with cerebral perfusion measures. There were 157 participants: 29 neurologically healthy controls (age: 70.3 6 6.6, MMSE Ն 27), 86 patients with mild AD (age: 69.18 6 8.28, MMSE Ն 21) and 42 patients moderate0severe AD (age: 68.86 6 10.69, MMSE 8-20). Single Photon Emission Computerized Tomography (SPECT) was used to derive regional perfusion ratios, and correlated using partial least squares (PLS) with neuropsychological test scores from the Benton Line Orientation (BLO) and the Rey-Osterrieth Complex Figure (RO). Cross-sectional analysis demonstrated that mean scores differed in accordance with disease status: control group (BLO 25.5, RO 33.3); mild AD (BLO 20.1, RO 25.5); moderate0severe AD (BLO 10.7, RO 16). Correlations were observed between BLO0RO and right parietal SPECT regions in the AD groups. Visuospatial performance, often undersampled in cognitive batteries for AD, is clearly impaired even in mild AD and correlates with functional deficits as indexed by cerebral perfusion ratios on SPECT implicating right hemisphere circuits. Furthermore, PLS reveals that usual spatial tasks probe a distributed brain network in both hemispheres including many areas targeted by early AD pathology. (JINS, 2008(JINS, , 14, 1034(JINS, -1045