Anhedonia is the word that describes the inability of a person to feel pleasure from the activities which they usually found enjoyable. It is a symptom of depression and other mental conditions. Studies have shown that anhedonia affects the part of the brain that is responsible for rewards, making decisions, motivational feelings, and anticipation. This, in turn, makes the person unable to feel good about positive happenings around them, or things which they previously felt good about.
The drugs readily available to treat patients who suffer from depression are those that act on serotonin receptors. However, recent studies by researchers at Queen’s University have shown that these drugs are not effective for the treatment of anhedonia. They discovered that since anhedonia suppresses the neurotransmitter – dopamine – that controls rewards, motivation, and productivity, using drugs that act on serotonin which controls feelings of happiness, calm, and focus, would not be quite effective for the treatment of anhedonia especially when it results from too much stress.
How did they discover this?
They carried out their experiments on an animal model – rats, subjecting 48 male rats to a three-week duration of stressful activities. Then, in an attempt to treat them, they injected half of the rats with a low dose of Amisulpride, a drug that increases dopamine activity in the brain; they injected the other half with Quinpirole (a psychotropic drug that targets the right site of action – D2 receptor agonist), specifically into one of the two regions of their brains that is known to control motivation and productivity – nucleus accumbens or medial prefrontal cortex.
At the end of their experiments, they found that the dopamine modulators improved the motivational feelings and levels of productivity of the rats, which were initially reduced by the three-week stressful activities. This improvement was more noticed in rats that were seriously affected during the stress period. The overall results gotten from the experiments show that patients who suffer from anhedonia, particularly those who have it as a result of stress, could be better treated with drugs that target dopamine, rather than those that target serotonin in the brain.
To be sure of this finding, they still need to carry out tests on real humans to know whether the same results would be gotten as with the experiments on the rats.
Findings from this study have provided a better medication to treat patients suffering from anhedonia, asides from the usual medications for depression which mostly work to induce serotonin activity in the brain.
This team of researchers has been able to discover the reason for the ineffective treatment of anhedonia using the usual anti-depressants, and have discovered a better medication for it.
This study has revealed a more effective way to treat anhedonia outside using the existing anti-depressants since they do not target the neurotransmitter that is disturbed when a person suffers from this symptom.