Certain Hostile Behaviors Signal Increased Huntington's Risk

Both a strong tendency to criticize others and delusional hostility may be present long before the classic and defining symptoms of Huntington's disease appear, a new study has found.

The study was headed by Evangelos Vassos, M.D., and conducted while he was a research fellow at the University of Athens in Greece. He is currently an honorary research associate at the Institute of Psychiatry in London. Results are in press with Biological Psychiatry.

Sixty-four subjects with a first-degree relative with Huntington's disease participated in the study. They were on average in their early 30s and thus 16 years younger than the usual age of onset for Huntington's. All knew that they had a 50 percent chance of carrying the mutated gene that causes the disease and thus getting the disease themselves.

The subjects were evaluated for psychiatric symptoms using the Structured Clinical Interview for DSM-IV (SCID), Mini Mental State Examination, Symptom Checklist 90, Snaith Irritability Scale, Hostility and Direction of Hostility Questionnaire, and Maudsley Obsessive Compulsive Inventory. At this point, neither the subjects nor Vassos, who evaluated them, knew who had the gene and who did not.

After that evaluation the subjects were genotyped. Twenty-nine were found to carry the Huntington's gene, while 35 did not. Vassos and his coworkers then assessed whether there were any psychiatric differences between those with the mutated gene and those without it.

The groups were comparable on cognitive state and general functioning. However, extroverted hostility was more often present in subjects who carried the gene, and the difference was highly statistically significant. The researchers then looked to see whether there was any significant link between having the Huntington's gene and having any of the three subtypes of extroverted hostility—criticism of others, delusional hostility (for example, “I believe I am being plotted against”), or acting out. They found a link for criticism of others and delusional hostility, but not for acting out. No link appeared between the presence of extroverted hostility in subjects and their expected time of disease onset.

These results indicate “that gene carriers have higher levels of extroverted hostility than noncarriers,” Vassos and his colleagues said in their report. “In line with this is the finding that extroverted hostility is not affected by the proximity to the age of onset of Huntington's, which suggests that gene carriers have a stable pattern of increased hostility starting apparently long before the onset of the disease... [and that this increased extroverted hostility] is not just reactive to the manifestation of the disease.”

In short, they concluded, extroverted hostility is an early marker for Huntington's disease.

Commenting on the implications of his findings in an interview with Psychiatric News, Vassos pointed out that there is no cure for Huntington's disease and no treatment preventing the development of the disorder or specific treatment for the hostility found in subjects at genetic risk. However, various drugs, particularly antipsychotics, have been used to treat abnormal movements, and antidepressants and mood stabilizers have been used to treat affective and behavioral problems related to the disease.

Vassos added that educating patients and their families about the possibility of some symptoms of hostility being explained by the mutated gene might reduce patients' guilt and unnecessary animosity within families. Finally, these findings might help during counseling or psychotherapy with individuals at risk of developing Huntington's.

“Overall, this study gives some insight that although Huntington's disease has traditionally been considered a neurological disease, there is scope for collaboration with psychiatry,” Vassos told Psychiatric News. “Clinical neurologists need to be aware of psychiatric manifestations of the disease—studies have indicated that emotional disturbances in Huntington's are often overlooked—and clinical psychiatrists need to acquire training in treating neuropsychiatric disorders.”

The study received no outside funding.

An abstract of “Higher Levels of Extroverted Hostility Detected in Gene Carriers at Risk for Huntington's Disease” is posted at<www.journals.elsevierhealth.com/periodicals/bps/article/PIIS0006322306015836/abstract>.▪