DENVER – Acquired sociopathy resulting from dementia is a common condition with two broad forms that require very different treatment strategies.

Demented patients who commit impulsive, sociopathic acts without emotion or concern for the consequences most often display frontal-caudate disturbances on functional neuroimaging. Their impulsive acts – for example, pathological stealing or disinhibited sexual behavior – tend to be nonviolent, Dr. Mario F. Mendez explained at the annual meeting of the American Neuropsychiatric Association.

Dr. Mario F. Mendez

In contrast, demented patients whose functional neuroimaging studies show more prominent temporal and parieto-occipital pathology are more likely to come to legal attention because of their nonimpulsive sociopathic acts, which are often violent in nature, said Dr. Mendez, professor of neurology and psychiatry and biobehavioral sciences at the University of California, Los Angeles.

Mechanistically, sociopathy in dementia results either from disinhibition secondary to frontal-predominant disease (such as vascular dementia, Huntington’s disease, or frontotemporal dementia), or from agitation and paranoia with memory and language impairment leading to misinterpretation of benign environmental cues as being hostile. Individuals with the nonimpulsive form tend to have advanced Alzheimer’s disease.

The hallmark of the impulsive form of sociopathy in dementia is lesions of the ventromedial prefrontal cortex, often with an additional contribution from the anterior temporolimbic area.

"Changes to the adjacent orbital frontal cortex region may be critical, resulting in impaired control of impulsive responses to tempting situations. Affected patients have impaired automatic feedback from social cues, especially angry or aversive expressions," according to Dr. Mendez, who is also director of the neurobehavior unit at the VA Greater Los Angeles Healthcare System.

As in psychopathy, sociopathy in dementia can take the form of goal-oriented aggression. But psychopathy differs from sociopathy in dementia in several key ways: Psychopathy first appears as antisocial behavior in childhood. And it is distinguished by additional features that are not found in sociopathy in dementia, including manipulation, callousness, grandiosity, sensation seeking, and deception.

To highlight the two broad types of sociopathy in dementia, Dr. Mendez presented his observational study of 33 affected patients. All of them had become involved with the legal system as a result of their behavior. In all, 22 were tagged for impulsive sociopathic acts and 11 for nonimpulsive acts.

The most common diagnoses among the 33 demented patients were Alzheimer’s disease, frontotemporal dementia, and vascular dementia or anoxic encephalopathy. Collectively, they accounted for 20 cases. But sociopathy has also been seen in association with many other brain diseases as well, including epilepsy, Parkinsonian syndromes, stroke, traumatic brain injury, and subarachnoid hemorrhage, Dr. Mendez said.

The 11 nonimpulsive patients were significantly older (mean age, 74 years), compared with age 62 for the impulsive group. The nonimpulsive group was also more impaired in language and/or cognition as reflected by their mean Mini-Mental State Exam score of 19.72, compared with 24.12 in the impulsive group.

On the Neuropsychiatric Inventory, the nonimpulsive patients scored higher on agitation, aggression, delusions, irritability, and depression. They demonstrated more impairment of language on the Category Fluency Test and the Mini-Boston Naming Test, performed worse on three-dimensional construction tasks, and their CERAD (Consortium to Establish a Registry for Alzheimer’s Disease) scores also showed greater memory impairment.

04/07/11