For millions of people fighting addiction, quitting is not just a matter of willpower, and research is just beginning to show why as new evidence suggests that substance abuse causes changes in brain function.
For people like Ms Rita Gatonye a resident of Nairobi who started experimenting with drugs back in 2015, its prolonged use caused her brain to stop making enough dopamine - a chemical released in the brain when something good happens, giving an addict some form of pleasure or euphoria.