Dual theories of depression: sex-specific genes and brain hemispheres yield new clues – Brain – Brief Article
Laurie Budgar Dwek
OF THE 19 CHROMOSOMAL REGIONS now known to influence depression, only three are found in both genders, according to researchers at the University of Pittsburgh School of Medicine. “Sex-specific genes for recurrent major depression may actually be the rule rather than the exception,” says George S. Zubenko, Ph.D., a professor of psychiatry at the university. Scientists knew that genetics accounted for 40 to 70 percent of the risk for developing major depression but could not heretofore confirm that the disease is sex-specific, despite symptomatic gender differences. Women report accompanying anxiety and eating disorders, while men tend to exhibit anti-social behavior and substance-abuse problems. The results were published in the American Journal of Medical Genetics.
Another study maintains that depression can be treated or exacerbated by electromagnetic stimulation, depending on the individual. In the dual-brain theory of Fredric Schiffer, M.D., an associate professor of psychiatry at Harvard, one hemisphere hosts a healthy worldview, while the other retains past emotions and trauma that may cause depression. Schiffer found that he could determine the “healthy” hemisphere by covering half the subject’s field of vision and asking emotionally charged questions. “Patients experienced amazing personality changes,” says Schiffer. “After stimulating one side, they were very negative and immature; after stimulating the other, very positive.”
Now, Schiffer and Alvaro Pascual-Leone, M.D., of Beth Israel Deaconess Medical Center in Boston, maintain that depressed patients with healthy left hemispheres are most likely to benefit from this treatment, known as transcranial magnetic stimulation (TMS). Schiffer assumed that stimulating the healthy hemisphere would improve mood. So Pascal-Leone applied TMS to the healthy left hemispheres of 20 clinically depressed subjects. Two weeks later, their symptoms decreased by 42 percent; a 50-percent reduction in symptoms signifies remission. Fifteen patients with healthier right hemispheres actually felt worse after treatment. The results were published in Neuropsychiatry, Neuropsychology, and Behavioral Neurology.
COPYRIGHT 2002 Sussex Publishers, Inc.
COPYRIGHT 2002 Gale Group