Posted by SLS on April 14, 2005, at 15:23:51
Brain Activity Before Therapy Flags Vulnerability to Antidepressant Side Effects
By Megan Rauscher
NEW YORK (Reuters Health) Apr 07 - Changes in prefrontal cortex activity just prior to the start of antidepressant drug therapy may identify patients who are vulnerable to side effects, the results of a small study suggest.
"Surprisingly, the brain changes that signaled antidepressant side effects emerged before the start of drug," Dr. Aimee M. Hunter from the University of California Neuropsychiatric Institute in Los Angeles told Reuters Health.
The ability to identify individuals at risk for developing side effects would improve the success rate of antidepressant treatment, she said. Physicians might choose an antidepressant with a lower side-effect profile, start at a lower dose, or opt for psychotherapy alone.
In a previous study of depressed adults, Dr. Hunter and colleagues showed that early changes in prefrontal cortex activity, demonstrated by decreases in quantitative electroencephalographic (QEEG) cordance values, correlate with clinical response to antidepressant drug therapy (see Reuters Health report June 14, 2002).
In the current study, the researchers explored the link between side effects and changes in brain activity, again using QEEG cordance measures, in 32 healthy subjects without a history of depression. The subjects received 1 week of placebo followed by 4 weeks of an antidepressant (venlafaxine) or placebo in a blinded fashion.
"Reported side effects doubled within 48 hours after start of the medication," Dr. Hunter told Reuters Health. Common side effects included nausea, difficulty sleeping, and decrease in sexual desire or ability. No subject reported suicidal thoughts or feelings at any point over the study.
According to Dr. Hunter, "changes in prefrontal cordance during the initial week of placebo treatment (placebo lead-in) were strongly associated with the average number of side effects reported during the following 4 weeks of antidepressant treatment."
It is possible that the prefrontal brain change observed during brief placebo treatment was a biomarker of subject expectations, Dr. Hunter said, noting that "beliefs and expectations about taking medication can play an important role in drug effects. To some extent you get what you expect."
Data from this study suggest that "whether a person will experience many or few side effects appears to be explained in large part by non-drug-induced changes in brain function," Dr. Hunter also noted.
"We're used to asking -- how does medication affect the brain? -- But this study gets us to ask -- how might the brain modify medication effects?"
The study appears in the April issue of the journal Neuropsychopharmacology.
Neuropsychopharmacology 2005.
poster:SLS
thread:484230
URL: http://www.dr-bob.org/babble/20050413/msgs/484230.html