Medial temporal hypoperfusion and aggression in Alzheimer disease.

BACKGROUND It is not understood why some patients with Alzheimer disease (AD) display aggression and others do not. OBJECTIVE To examine the relation between regional brain perfusion and aggression in AD. DESIGN Single-photon emission computed tomographic scans were coregistered to a standardized template in Talairach space, generating mean ratios of uptake referenced to the cerebellum. PARTICIPANTS Forty-nine outpatients (25 men and 24 women; mean +/- SD age, 74 +/- 11 years) with probable AD (Mini-Mental State Examination score, 17.7 +/- 5.0; 30 aggressive and 19 nonaggressive), comparable in age, sex, and severity of cognitive impairment. MAIN OUTCOME MEASURES Regional perfusion ratios were determined for 5 bilateral regions of interest: orbitofrontal, middle medial temporal, inferior medial temporal, hypothalamus/thalamus, and anterior cingulate. RESULTS Compared with nonaggressive patients, aggressive ones displayed hypoperfusion in the right and left middle medial temporal regions of interest (P = .02 for both), but not the others (all (t tests, unpaired, 2-tailed). On regression analyses, right middle temporal hypoperfusion (P = .001), younger age (P = .002), greater activity disturbances (P = .004), and higher Mini-Mental State Examination scores (P = .04) independently predicted aggression, accounting for 44% of the total variance (F = 8.7; P<.001). Statistical parametric mapping analyses supported right middle medial temporal hypoperfusion in the aggressive group (P = .008). CONCLUSION In this sample of patients with AD, the right middle medial temporal region emerged as an important neural correlate of aggression.