The study, which is published in the December 13, 2005, issue of Neurology, the scientific journal of the American Academy of Neurology, found that the rate of depression and anxiety disorders decreased by more than 50 percent up to two years after the surgery. People who no longer experienced any seizures after surgery were even more likely to be free of depression and anxiety.
"These results are important because depression and anxiety can significantly affect the quality of life," said study author Orrin Devinsky, MD, Professor of Neurology, Neurosurgery, and Psychiatry at New York University School of Medicine and Director of the NYU Comprehensive Epilepsy Center. "For people with refractory epilepsy, studies show that depression is more likely to affect their quality of life than how often they have seizures or how many drugs they have to take."
The study involved 360 people in seven U.S. epilepsy centers who were undergoing epilepsy surgery to remove the area of the brain producing the seizures. Epilepsy surgery is generally reserved for those whose seizures cannot be adequately controlled by medication. The majority of participants had surgery on the brain's temporal lobe. The participants' mental health and any symptoms of depression and anxiety were evaluated before surgery and at three months, one year, and two years after surgery.
Prior to the surgery, 22 percent of the participants met the criteria for a diagnosis of depression, compared to 9 percent two years after the surgery. For anxiety disorders, 18 percent met the criteria for a diagnosis before the surgery, compared to 10 percent two years after the surgery.
Of those who had no seizures following surgery, 8 percent met the criteria for depression, compared to 18 percent of those who still had some seizures after surgery. For anxiety, 8 percent of those who were seizure free had depression, compared to 15 percent of those with ongoing seizures.
Researchers aren't sure why depression and anxiety improve after epilepsy surgery. "Removing dysfunctional areas of the brain may be critical," Devinsky said. "Whether the benefit comes from reducing or eliminating seizures or other effects is not clear. People may also be benefiting from an improved sense of self-control, less fear of seizures, higher activity levels and a lessened burden from medications."