Depression, understood as a disabling medical condition, is one of the most misunderstood psychological distresses by the general public. Depression is insidious, often manifesting as gradual loss of interest in normally pleasurable activities for patients, to potentially culminate in suicide attempts. When the condition is chronic, treatment may include not only psychotherapy, but drugs that alter brain chemistry to help patients returning into a state in which they have enough motivation to continue his life.
Chronic pain in the past has been characterized as a condition comorbid to clinical depression, but this completely ignores the understanding of pain and its effects on the body. In a new study at Stanford University, Dr. Neil Schwartz investigated the loss of motivation based on chronic pain. Dr. Schwartz monitored motivation for food in laboratory mice with injuries causing pain to measure their response to the pleasant stimuli. This made the rodents less liking to feed themselves. Even after application of drugs which increased the pain threshold in the animals, reduced motivation was constant. This is similar to the depression cycle, where difficulties decrease motivation for pleasurable activities, resulting in a reduction of positive emotions in patients. These proceedings reinforces the vicious circle, since they further fuels depression.
Once the behavioral studies were completed, researchers began studies of neurons, both inside and outside the body. They found, in the brain reward circuitry, that all changes were consistent with reduced effort and motivation. They suspect that a protein called galanin (which typically plays a role in the communication between neurons) influences in this reward circuitry. In modified mice with eliminated galanin production experienced restoration on feeding motivation, even those mice with injuries and chronic pain did. In mice where the protein was present (even small amounts), it activated a route of metabolism that reduced motivation.
In the long term, researchers hope that categorizing this protein may clarify its role in the reward system; opening the way for designing drugs that could moderate the impact on the motivation of both, chronic pain and clinical depression, patients.
Via: arstechnica.com
