Disease and drugs can produce faulty sensitization Sensitization or desensitization normally occur with drug exposure. However, addiction or mental illness can tamper with the reuptake system. This disrupts the normal levels of neurotransmitters in the brain and can lead to faulty desensitization or sensitization. If this happens in a region of the brain that serves emotion or motivation, the individual can suffer severe consequences. Consider an example.
Cocaine prevents dopamine reuptake by binding to proteins that normally transport dopamine.
As a result, more dopamine remains to stimulate neurons, which causes a prolonged feelings of pleasure and excitement. Amphetamine also increases dopamine levels.