Experts say drugs act as chemicals that mimic the neurotransmitters of the brain's reward system but in many cases, using these illicit substances can affect the reward system more critically.
Just like Ms Gatonye, Mr Nahashon Poel from Kiambu County also found himself in the vicious addiction cycle as what was meant to numb the pain from a marital breakdown that left him feeling dejected and unworthy developed into an urge that became too strong to control.
He resorted to self-medication, or rather "drowning his sorrows", in a misadvised attempt to regulate the intense negative emotions that emanated from the failed marriage.
"I would be so drunk that I would just bring some bottles along just in case the effects of the alcohol died down," says Mr Poel, who is also a disc jockey. "Alcohol became my best friend at this time and, eventually, I became a very hardworking alcoholic... until I went broke."
Psychologists say when we engage in new rewarding behaviors, the brain also builds a connection between that behavior and related cues. In this case, alcohol was his new-found love, some sort of a coping mechanism and a getaway from the reality that tormented his very existence.
Unable to cope in the city, he relocated upcountry, where he spent most of his days in alcohol dens. Soon, he became suicidal, and before he knew it he had descended into a dark, dangerous pit from which only he could help himself crawl out.
More often than not, people like Mr Gatonye and Mr Poel face a lot of stigma due to addiction. Questions like "why don't they just quit?" often pop up whenever the effects of drugs take a toll on them.
But now science shows that substance use disorders are complex chronic and treatable medical conditions, and that their management is best approached from the understanding that they change the functions of their victims.
"If you take a drug, like alcohol, you feel happy, and when you are intoxicated it disinhibits you," says Dr Ruth Korir, a psychiatrist at Mathari Teaching and Referral Hospital in Nairobi.
She adds: "One's judgement is also impaired because the brain function is affected, which is why addiction is regarded as a disease."
Similarly, the consequences of drug abuse are vast and varied. They interfere with the way neurons - the electrical signals that transmit information to different parts of the brain, send, receive and process cues via neurotransmitters.
If an individual takes a drug and feels euphoric and they like that feeling, Dr Korir cautions, "they'll end up looking for that drug again so that they can get that excessive feeling."
The chemical structure of some drugs like marijuana, known locally by the more common name, bhang, can activate neurons because it mimics that of a neurotransmitter. But there is a problem: as much as they activate the neurons, they don't do so in the same manner as a natural neurotransmitter, and this eventually leads to abnormal messages being sent through the brain network.
Drugs are classified into different types. There are antidepressants that make the brain work faster; depressants, which slow down the brain; and hallucinogens, which cause alterations in thought, mood, and perception. In this regards, experts say the long-term use of some addictive substances, such as alcohol, causes physical changes to the brain. Particularly, it shrinks and affects the ability of one to process information.
"Alcohol is classified as a depressant, so most likely the brain function will slow down. It impairs judgement, concentration and even speech," says Dr Korir.
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