Depression and addiction occur together often enough that treating one while leaving the other alone is one of the more common reasons treatment does not hold. Among people with major depression, alcohol use disorder shows up in roughly a quarter to two-fifths of them over a lifetime, and the overlap runs in both directions: about half of people who develop a substance use disorder will also experience a mental illness, and about half of people with a mental illness will develop a substance use disorder. In Malaysia, the National Anti-Drugs Agency (AADK) recorded 5,030 people with drug addiction between January and March 2026, and 1,346 of them, about 27 per cent, also had a mental health disorder. Across 2025 the figure was 6 per cent. Depression itself has been rising too: the number of Malaysians aged 15 and above with depression doubled between 2019 and 2023, to around one million people, with the increase concentrated among those aged 16 to 29.
Which comes first
Either can come first.
Some people are depressed, anxious or carrying trauma first, and drink or use drugs because it is the only thing that quiets it, even though it makes the underlying problem worse over time. This is usually described as self-medicating, and it is one of the most common patterns families describe once they start asking questions.
Other times, heavy substance use comes first and produces the depression as a direct effect. Years of heavy drinking or drug use change how the brain regulates mood and reward, and low mood, flat affect and loss of interest in ordinary life follow as a result. Genetics and adverse experiences such as childhood trauma raise the risk of both conditions independently, which is part of why they cluster together in the same person so often.
Why treating one and leaving the other tends to fail
Treat the depression with medication and therapy while heavy drinking or drug use continues, and the substance use tends to undo the treatment. Alcohol and most drugs of misuse lower mood over time in their own right, and a return to use is one of the more common reasons antidepressant treatment appears not to work.
Treat the addiction alone and leave the depression untreated, and the depression is often what brings the substance use back. Someone who gets through withdrawal and a few weeks of abstinence but is still waking up flat, hopeless and without energy has a strong reason to return to the one thing that used to make that feeling go away.
The research is consistent on this. People treated for both conditions at once do better than those treated for either alone, while people whose comorbid conditions go untreated have poorer treatment adherence and drop out of care more often.
Telling ordinary low mood apart from withdrawal-related low mood
Stopping alcohol or drugs, on its own, can produce something that looks exactly like depression: low energy, poor sleep, no appetite, no interest in anything. Clinically, this is treated as a separate question from whether someone has an underlying depressive illness, and the way to tell the two apart is time.
Depressive symptoms caused directly by substance use or withdrawal usually ease within days to a few weeks once the substance is out of the person's system. If low mood is still there roughly a month after withdrawal should have settled, and especially if it was present before the heavy drinking or drug use started, that points to a depressive illness in its own right, which needs its own treatment. This is why a proper assessment happens after a period away from the substance, not on the first day, and why a diagnosis made in the first week of stopping is often the wrong one.
What integrated treatment looks like
At Salus, every guest is seen by a psychiatrist on arrival, and the assessment that follows leads to a diagnosis. That diagnosis decides the therapy, whether that is cognitive behavioural therapy, REBT, solution-focused therapy, motivational interviewing or trauma-focused work, and it is revisited as withdrawal settles and a clearer picture emerges. Psychiatrists and psychologists work from the same plan, so mood, anxiety, trauma and sleep are treated alongside the dependence itself at the same time. The Social Prescription Model, a clinical prescription alongside a living prescription built with a Salus Clinician, runs through the full 90 days, so the person has a daily life worth protecting once the depression lifts and the substance is gone.
What to do today
If someone is thinking about ending their life, treat it as urgent. Call 999, call Befrienders KL on 03-7627 2929, which runs 24 hours a day, or go to the nearest emergency department.
Outside of that immediate danger, if you are seeing depression and heavy drinking or drug use together in someone you love, get in touch with Salus for a confidential conversation about what an assessment involves. If you are not sure how to start that conversation, our guide on talking to someone about getting help may help, and our page for families covers what to expect once treatment begins.
