Alzheimer Disease: Functional Abnormalities in the Dorsal Visual Pathway

• Published in: Radiology Vol. 254; no. 1; pp. 219 - 226
• Main Authors: BOKDE, Arun L. W, LOPEZ-BAYO, Patricia, BORN, Christine, EWERS, Michael, MEINDL, Thomas, TEIPEL, Stefen J, FALTRACO, Frank, REISER, Maximilian F, MÖLLER, Hans-Juergen, HAMPEL, Harald
• Format: Journal Article
• Language: English
• Published: Oak Brook, IL Radiological Society of North America 2010
• Subjects: Adult; Adult and adolescent clinical studies; Aged; Alzheimer Disease - physiopathology; Biological and medical sciences; Brain Mapping; Case-Control Studies; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; Female; Humans; Magnetic Resonance Imaging - methods; Male; Medical sciences; Neurology; Neuropsychological Tests; Organic mental disorders. Neuropsychology; Photic Stimulation; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Task Performance and Analysis; Visual Cortex - physiopathology; Visual Perception - physiology; Nervous system diseases; Degenerative disease; Alzheimer disease; Central nervous system disease; Cerebral disorder
• ISSN: 0033-8419; 1527-1315
• DOI: 10.1148/radiol.2541090558

To evaluate whether patients with Alzheimer disease (AD) have altered activation compared with age-matched healthy control (HC) subjects during a task that typically recruits the dorsal visual pathway. The study was performed in accordance with the Declaration of Helsinki, with institutional ethics committee approval, and all subjects provided written informed consent. Two tasks were performed to investigate neural function: face matching and location matching. Twelve patients with mild AD and 14 age-matched HC subjects were included. Brain activation was measured by using functional magnetic resonance imaging. Group statistical analyses were based on a mixed-effects model corrected for multiple comparisons. Task performance was not statistically different between the two groups, and within groups there were no differences in task performance. In the HC group, the visual perception tasks selectively activated the visual pathways. Conversely in the AD group, there was no selective activation during performance of these same tasks. Along the dorsal visual pathway, the AD group recruited additional regions, primarily in the parietal and frontal lobes, for the location-matching task. There were no differences in activation between groups during the face-matching task. The increased activation in the AD group may represent a compensatory mechanism for decreased processing effectiveness in early visual areas of patients with AD. The findings support the idea that the dorsal visual pathway is more susceptible to putative AD-related neuropathologic changes than is the ventral visual pathway.