Hypofunction in the posterior cingulate gyrus correlates with disorientation for time and place in Alzheimer's disease.

The relation between orientation for time and place and regional cerebral glucose metabolism was examined in 86 patients with probable Alzheimer's disease of minimal to moderate severity. Regional glucose metabolic rates in the posterior cingulate gyri and in the right middle temporal gyrus were significantly correlated with temporal orientation, and the glucose metabolic rate in the right posterior cingulate gyrus was significantly correlated with locational orientation irrespective of age, sex, education, and memory impairment. The results suggest that dysfunction of these structures plays an important part in producing disorientation in patients with Alzheimer's disease.