Dr. Diana Rosas
Massachusetts General Hospital
Dr. Rosas is a clinician who treats people with HD. The complexity and mysterious nature of the illness inspired her to get involved with Dr. Nancy Wexler’s Venezuela project in the early 1980s—a genetic study of large families that were all descended from a single ancestor with HD. The goal of the project was to generate a precise map of genetic markers.
Since then, Rosas has dedicated her life to treating the symptoms experienced by people with HD, as well as to investigating the effects of HD on the brain. In contrast to researchers like Drs. James Gusella and Marcy MacDonald (please see Chapter 1, Part 1 of Research Frontiers who direct their efforts toward the root causes of HD and the beginning of the disease cascade, Rosas and other clinicians focus on the end of the cascade, in which motor, cognitive, and psychiatric functions begin to decline. Rosas defines the age of onset of HD as the age when motor symptoms (irregular eye movements, chorea, etc.) appear. Interestingly, some people are able to suppress their chorea during a doctor’s examination, and, as a result, their HD goes undiagnosed for a long period of time.
Rosas also discussed the unique onset of juvenile HD. Children with greater than 45 CAG codon repeats in the Huntington gene have an earlier and much more severe onset than people with traditional HD. While these children experience less chorea than their adult counterparts, they often have hallucinations and symptoms that resemble those of Parkinson’s disease.
Although she acknowledges that it is important for clinicians to concentrate on the striatum, where neurodegeneration starts, Rosas mostly takes a holistic approach to the brain. She emphasizes that the entire brain, not just the striatum, deteriorates as a result of HD.
“The motor cortex is affected across the board,” said Rosas. Located on the frontal lobe, the motor cortex carries out the initial processing of motor information in the brain and is involved in the control of movement.
The earliest changes in the brain occur in the posterior regions (the parietal, occipital, and temporal lobes). During the course of the disease, however, a person experiences large reductions in volume in almost all areas of the brain. For example:
To learn more about the different parts of the brain, please click here.
The treatment of HD requires an integrated, multidisciplinary approach that includes the medical management of symptoms; physical, occupational, and/or speech therapy; and genetic and psychological counseling. In addition to treating people who already have the disease, Rosas counsels people who are at risk for developing it. While the decision to undergo genetic testing is a very personal one, Rosas does recommend it for those who are planning to have children.
She encourages all others at risk not to undergo testing for several reasons. First, there is no cure for HD. Second, insurance issues and genetic discrimination in the workplace may result if an at-risk person finds out that he or she is likely to get the disease. Third, knowing that one is likely to get HD would cause unnecessary worry. He or she would constantly wonder, “When will I get sick?” Fourth, even negative test results may cause emotional distress, such as “survivor’s guilt” if one’s parents died from HD.
Finally, Rosas strongly advocates seeing a doctor for a complete neurological examination as soon as one notices the first physical symptoms of HD. She advises people not to wait. A doctor is the best judge of whether or not someone has the disease. Sometimes, though, people do experience sexual, mood, and marital problems even before the onset of motor symptoms. These problems are symptoms associated with the psychosocial part of the disease, and are most common in men. Many psychosocial symptoms can be treated by clinicians and psychologists.
For those who have been diagnosed with HD and are interested in participating in clinical trials, Rosas recommends visiting the website of the Huntington Study Group. Among its many resources, the website provides information about clinical trials in progress and new clinical trial initiatives.
-T. Altman, 5/5/06