Cognitive Behavioral Therapy (CBT) which aims to train depressed patients not to think negative thoughts about themselves causes a different pattern of changes to the brain than the changes caused by anti-depressant drugs.
Using positron emission tomography (PET) -- multi-colored imaging that pinpoints where maximum changes in brain metabolism occur -- Dr. Mayberg's team, led by CBT expert Zindel Segal, PhD, and graduate student Kimberly Goldapple, generated a detailed picture of what this self-correction looks like.
CBT has theoretically been considered a top-down approach because it focuses on the cortical (top) area of the brain -- associated with thinking functions -- to modulate abnormal mood states. It aims to modify attention and memory functions, affective bias and maladaptive information processing. In contrast, drug therapy is considered a bottom-up approach because it alters the chemistry in the brain stem and limbic (bottom) regions which drive more basic emotional and circadian behaviors resulting in eventual upstream changes in depressive thinking.
In this current study in Archives, 14 clinically-depressed adult patients underwent a full course of CBT. They each received 15 to 20 individualized outpatient sessions. None were on drug therapy. The patients' brains were scanned prior to beginning treatment and at the end of the full course of therapy.
Investigators found that CBT targets many of the same limbic and cortical regions affected by drug therapy, but in 'different directions'. With drug therapy, metabolism (blood flow) decreases in the limbic area and increases in the cortical area. With CBT, Mayberg and colleagues identified the reverse pattern: limbic increases (in the hippocampus, dorsal mid cingulate) and cortical decreases (in the dorsolateral, ventrolateral and medial orbital frontal; inferior temporal and parietal). Furthermore, each treatment showed changes in unique brain regions supporting the top-down, bottom-up theories.
What explains this reverse pattern? As CBT patients learn to turn off the thinking paradigm that leads them to dwell on negative thoughts and attitudes, activity in certain areas in the cortical (thinking, attention) region are decreasing as well.
"The challenge continues to be how to figure out 'how to best treat' for what the brain needs," says Dr. Mayberg. She suggests that brain scans may one day become a useful component of the treatment protocol for clinically depressed patients, helping doctors to determine in advance what treatment will be most efficacious, as well as monitor the effectiveness of a particular treatment strategy.
Both types of treatment work on only a subset of all depressed patients and the two different subsets only partially overlap. If patterns in the brains of depressed patients could be found that show how depressed patients differ from each other it might be possible to discover markers for which type of therapy is most likely to work. Some day depressed patients may have their brains scanned to determine what type of anti-depressant treatment has the best chance of working for each patient.
"This experiment lays the groundwork for looking for different markers that will help to optimize the treatment for a given individual; that's the really cool part," said Mayberg, a professor of psychiatry and neurology who conducted the study while at the University of Toronto but recently moved to Emory University in Atlanta.
Genetic testing will probably become even more common than brain scanning for the purpose of choosing the optimal therapy for treating depression. The genetic testing will be cheaper and easier to carry out. Also, genetic testing will be useful for identifying which anti-depressant drugs are more or less likely to work and more or less likely to cause side effects for each person.
Also, it may eventually become possible to automate much of the delivery of cognitive behavioral therapy. An interactive computer could be used to do part of the training of how to avoid thinking negative thoughts. It may also become possible to implant sensors and something like a hearing aid that would be triggered to tell a patient what positive thoughts to have when the sensors detect negative thoughts. Of course such a method of treatment would bring with it the potential of abuse as a means to control people.
|Share |||Randall Parker, 2004 January 08 12:03 AM Biological Mind|