Aripiprazole, sold by Bristol-Meyers Squibb under the trade name Abilify, is an atypical, or “second generation” antipsychotic medication usually prescribed for the treatment of schizophrenia, bipolar disorder and depression. Originally given the green light by the FDA in 2002, Abilify was approved for the treatment of depression in 2007. It is part of a class of drugs known as “dopamine agonists,” although aripiprazole itself is classified as a “partial dopamine agonist.”
Dopamine is a biochemical substance in the brain that functions as a neurotransmitter – in other words, it carries signals to and from the brain. While dopamine has many different functions – including muscle control, regulating kidney function and as a vasodilator – it is most often associated with the brain's “pleasure centers,” playing a significant role in addictive behaviors. A 2013 article in the U.K. Guardian described dopamine as “the nerd at the pool party who gives a running commentary on how well you're doing with the temptations on offer.”
However, it is a bit more complicated than that. Dopamine is not simply a “feel good” chemical. More accurately, it is a signal that tells the brain when one is closing in on a reward. It doesn't simply activate the reward pathways of the brain when one has achieved a desired result. Those pathways activate even in cases in which the subject has come close to the desired reward, but has fallen just short of obtaining it.
It is what keeps addicts searching for the next “high.” When it comes to compulsive behaviors such as gambling, dopamine encourages the subject to keep trying, even when they lose. In a 2010 study of roulette players, researchers found as much dopamine activity in the brains of gamblers who had just missed hitting the lucky numbers as those who had won the jackpot. It is not just signaling pleasure in achieving one's desires, it also indicates how close the subject came to success – and encourages him or her to keep trying.
This can be a good thing when it comes to activities involving the development of mental and physical skills. It is what keeps a musician practicing scales and etudes, and motivates an athlete to continue training. Unfortunately, those dopamine pathways do not know the difference between improving a skill by one's own efforts and getting lucky.
The same principle applies to a gambler. Each “near miss” encourages the subject to keep laying his or her money down. It can lead to a form of addiction – and as many recovering addicts will testify, it finally gets to the point that the activity no longer brings pleasure – but they are compelled to continue with the behavior simply in order to keep from feeling bad.
Dopamine agonists such as aripiprazole activate dopamine receptors in the brain, literally opening up those pathways. Among the resulting side effects are euphoria, increased orgasmic activity and pathological addictions that include compulsive gambling, shopping, binge eating and sexual behavior.
While full dopamine agonists bind to the complete range of receptors, Abilify – a “partial” agonist – binds only to certain receptors. One of them is the 5-HT2C receptor, which binds to serotonin. This is a neurotransmitter associated with the regulation of emotional state – particularly to positive feelings – as well as appetite and memory/cognitive function. It is one explanation of how Abilify can cause certain patients to engage in compulsive behaviors – something that the manufacturer should have been aware of, and certainly should have notified the FDA and warned patients once they became aware.