A single-photon emission computed tomographic study of anosognosia in Alzheimer's disease.

OBJECTIVE

To examine the presence of specific regional cerebral blood flow correlates of anosognosia in patients with probable Alzheimer's disease.

DESIGN

Case series, group comparisons.

SETTING

Ambulatory care referral center.

PATIENTS: Twelve patients with probable Alzheimer's disease and anosognosia and 12 patients with probable Alzheimer's disease without anosognosia who were matched for age, duration of illness, and cognitive impairments.

MAIN OUTCOME MEASURES: Single-photon emission computed tomographic scan studies with technetium Tc 99m hexamethylpropylene-amine oxime and regional cerebral blood flow measurements.

RESULTS

Patients with Alzheimer's disease and anosognosia showed significant blood flow deficits in the frontal inferior and superior (dorsal) areas of the right hemisphere. On the other hand, no significant between-group differences were found in depression scores and neuropsychological tasks that assessed verbal and visual memory, verbal comprehension, naming, verbal fluency, auditory attention, abstract reasoning, and set-shifting abilities.

CONCLUSIONS

Our study demonstrates that anosognosia may not be related to deficits in specific cognitive domains, but it may result from dysfunction of the right frontal lobe.