In 2014, approximately 1 in 10 people suffered from drug addiction, meaning most people know someone who is a current or recovering addict.2 Luckily, today’s society is moving away from an era that stigmatized addiction as a choice and into a world that acknowledges addiction as a legitimate disease.
Few drug users, if any, stop and think about how their background – race, age, gender – may affect their drug use, likely due to the fact that information in this area is not common knowledge. Therefore, it may be shocking to many that cocaine affects men and women differently: women become addicted to cocaine faster and, once clean, are more likely to relapse than their male counterparts. In a 2017 study, researchers targeted this finding in an attempt to define the underlying causes of this phenomenon, and, by doing so, hopefully aid in improving treatment for female cocaine addicts.
While people joke that men and women come from different planets, the most obvious difference between males and females comes down to biology: testes or ovaries? This fundamental difference underlies the difference in cocaine addiction in male versus female mice. Female mice and women experience similar changes in hormone circulation in response to their reproductive cycles; both have periods of heightened fertility during which female sex hormones are in greater circulation in the body.1, 4 In mice, this period is called oestrus, and the research team discovered that females have an increased susceptibility to cocaine’s effects during this stage. Furthermore, it is the increased levels of estradiol (a female sex hormone) during oestrus that correlates to the increased potency of cocaine.
A quick neurobiology crash course: neurotransmitters are the chemicals in our brains that control communication between every part of our bodies and result in everything from our ability to walk to the fear felt during horror movies. Despite dopamine’s reputation in popular culture as the pleasure neurotransmitter, it is actually responsible for desire and reward, controlling cocaine craving. During oestrus, estradiol increases dopamine activity, meaning more activity is occurring in the parts of the brain involved in craving and reward. Therefore, cocaine becomes more rewarding to oestrus females. After dopamine is released, a molecule called Dopamine Transporter (DAT) removes it in order to allow new signals to come through. Cocaine causes the sensation of being high by blocking DAT, meaning dopamine is doing its job for longer. When females are in oestrus, it takes much less cocaine to block DAT than it does for males or non-oestrus females, making cocaine even more pleasurable than it usually would be for oestrus females.
Past work has shown that mice with depressive behaviors often have increased activity in the reward and craving centers of the brain, combined with greater responses to stimulants like cocaine; statistics also show that humans suffering from mental illness are twice as likely to be afflicted by addiction.3 Therefore, this research offers hope not only to cocaine-addicted women, but to those dealing with overlapping mental illness and addiction as well.
1 Calipari, E. S. et al. Dopaminergic dynamics underlying sex-specific cocaine reward. Nat. Commun. 8, 13877 doi: 10.1038/ncomms13877 (2017).
2 “Statistics on Drug Addiction.” Americanaddictioncenters.org. N.p., n.d. Web. 19 Feb. 2017. <http://americanaddictioncenters.org/rehab-guide/addiction-statistics/>.
3 Zwolinski, Richard C.R. “Depression and Substance Abuse: The Chicken or the Egg?” PsychCentral. N.p., 17 May 2016. Web. 8 Mar. 2017.
4 Jackson, L. R., Robinson, T. E. & Becker, J. B. Sex differences and hormonal influences on acquisition of cocaine self-administration in rats. Neuropsychopharmacology 31, 129–138 (2006).
5 Belcher, Lauren. “Cocaine – The Mix”. The Mix. N.p., 2017. Web. 8 Mar. 2017.