Friday, 20 Jul, 2007 Science

Scientists Discover New Facts about 'Placebo Effect'


New study conducted by scientists helped them discover a brain region responsible for the placebo effect when a person strongly believes in the effectiveness of the received treatment, thus boosting its effect. Even if a patient is given a sugar pill instead of real drug, his belief in the therapeutic effect actually makes him feel better.

The University of Michigan researchers studied the nucleus accubens (NAC), a region found deep in the brain that turned out to be of great importance in reward expectation. Previous research led the scientists to the thought that the NAC may be related to the placebo effect. The participants of the study were told that they would help scientists test a new pain-killer and they would get either the real drug or a placebo. However, the researchers gave a a placebo injection to every participant of the study.

During the first experiment, the scientists made use of the positron emission spectroscopy and measured the neurotransmitter dopamine released from the NAC. The neurotransmitter dopamine represents a chemical trigger for the reward response provided by the brain.

The dopamine release from the NAC turned out to be directly connected to the participants' expectation of the benefit provided by the pain killer - the greater the expectation, the greater the dopamine release. Moreover, those study participants who claimed they felt more relief from the 'drug' while they experienced real pain, displayed greater NAC activity when they were given the placebo before they felt the pain.

During the second experiment, the scientists told the participants they would be given different amounts of money rewards. The scientists scanned the participants' brains with help of functional magnetic resonance imaging. The participants who displayed greater NAC activation during the reward processing also displayed greater anticipation of the placebo effectiveness.

The study authors made the conclusion that the NAC system should be activated to cause the placebo effect. This theory may be really helpful in developing new therapies for a range of conditions.

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