|Vol. 3, No. 2, 1997 Page 3|
A new study of patients with dementia offers evidence that abnormalities of the frontal and temporal lobes can predispose an individual to antisocial or violent behavior. The study's findings, authors B. L. Miller et al. say, "offer a compelling reason for continuing the exploration of possible structural and/or functional abnormalities in the brain associated with criminal activities."
Miller et al. studied the frequency of antisocial behaviors in two groups of patients: 22 with dementia due to progressive dysfunction of the anterior frontal and temporal cerebral lobes, and 22 with Alzheimer's disease, which primarily affects the hippocampus and posterior parietal and temporal lobes. Both groups were diagnosed through neuropsychological tests, clinical evaluations, and SPECT (single photon emission computerized tomography) and magnetic resonance imaging studies. The researchers determined the number of antisocial acts committed by each patient by questioning patients and their families and reviewing subjects' medical records.
The researchers found that ten of the 22 subjects with frontal-temporal dementia (FTD) had histories of socially disruptive behaviors. "Three FTD patients were arrested," they say, "[and] two others had relatives who prevented their arrest by convincing authorities that the FTD subject was 'sick'." Behaviors reported in the FTD patients included stealing, physical assaults, sexual comments and advances, indecent exposure, public urination, unethical job conduct, and a hit-and-run. In comparison, only one of 22 patients with Alzheimer's disorder had a history of socially disruptive behavior.
Because nearly all of the subjects were classified as having only mild dementia at the time of the study, Miller et al. say, "the behaviors cannot be attributed to confusion or severe dementia in either group." They add that the antisocial behaviors seen in the FTD group also cannot be explained by the theory that brain dysfunction simply magnified existing personality traits. Relatives of the FTD patients, the researchers note, described them as "responsible, high-functioning adults" before the onset of their dementias.
The researchers say their study "supports a relationship between frontal- temporal dysfunction and certain types of antisocial activity." They suggest that their findings are relevant to criminal research, pointing out that "recent work suggesting a strong anatomical basis for murder, with perpetrators demonstrating marked frontal (64.5%) or temporal (29%) deficit, has been reported." (See related article, Crime Times, Vol. 1, No. 4, Page 1.)
"The present study," Miller and colleagues say, "may have relevance to the question raised so often in moral and legal arenas, 'Why in the world would this person have behaved in a manner so unlike himself?'"
"Aggressive, socially disruptive and antisocial behaviour associated with fronto-temporal dementia," B. L. Miller, A. Darby, D. F. Benson, J. L. Cummings, and M. H. Miller, British Journal of Psychiatry, 170, 1997, pp. 150-155. Address: B. L. Miller, Professor of Neurology, Harbor-UCLA Medical Center, 1000 W. Carson Street, Torrance, CA 90509, fax (310) 618-1273.