The drinking or the drug use is rarely the whole story. Behind it there is often something quieter and older: a depression that has never lifted, an anxiety that makes ordinary days feel like too much, a trauma nobody talks about. A person reaches for something to take the edge off, and for a while it seems to work. Then the substance stops being the relief and becomes the problem too. By that point, two things are tangled together, and pulling on one tightens the other.
When a substance use disorder and a mental health condition exist in the same person at the same time, clinicians call it a dual diagnosis, or co-occurring disorders. It is far more common than most families realise, and it changes what real treatment needs to look like.
How addiction and mental health feed each other
Addiction and mental illness are not separate boxes. They affect the same parts of the brain, the circuits that regulate mood, reward, stress and decision-making. That overlap is part of why the two so often travel together.
The relationship usually runs in one of three directions, and sometimes in all of them at once. According to the National Institute of Mental Health, shared risk factors like genetics, chronic stress and trauma can set the stage for both conditions. A mental health condition can come first, with someone using substances to dull symptoms that have never been properly treated. Or heavy substance use can come first and trigger lasting changes in the brain that increase the risk of anxiety, depression or psychosis.
This is not a small overlap. Drawing on the 2023 National Survey on Drug Use and Health, the National Institute on Drug Abuse reports that around 35% of adults with a mental disorder also have a substance use disorder. The same research notes that more than 30% of adults with a substance use disorder had experienced childhood trauma. None of this means a person is weak or broken. It means addiction is a health condition with roots, and those roots matter.
What substances do to mood over time
Most drugs work by flooding the brain with chemicals that signal pleasure or calm. Use them often enough and the brain adjusts. It produces less of those chemicals on its own and starts to depend on the substance to feel anything close to normal.
The result is a cruel kind of maths. The thing someone uses to feel better leaves them feeling worse once it wears off. Anxiety sharpens. Mood drops. Sleep falls apart. For someone who was already struggling emotionally, this turns into a loop: use to escape the bad feelings, then face stronger bad feelings as the substance leaves the body, then use again. The brain’s reward system also dulls to everyday pleasures, so food, company and the things a person used to enjoy stop registering. Recovery, in part, means giving that system time to recover too.
The mental health conditions most often linked to addiction
Several conditions show up again and again alongside substance use. The most common include depression, anxiety disorders, bipolar disorder, post-traumatic stress disorder and, less often, schizophrenia.
- Depression: Substances can offer a brief lift, but they deepen low mood over time and raise the risk during withdrawal.
- Anxiety: Alcohol and sedatives can quiet a racing mind for an hour or two, then leave anxiety worse than before.
- PTSD and trauma: Drugs and alcohol may bury painful memories temporarily, but they tend to make flashbacks and emotional swings harder to manage.
- Bipolar disorder: Substance use can trigger or intensify both the high and the low phases, and can interfere with medication.
Knowing which condition is in play matters, because it shapes the treatment. Reading more about the psychological effects of drug addiction can help families understand what they are seeing, and why willpower alone so rarely settles it.
Why treating only one side usually fails
Here is the trap that catches so many people. Treat the addiction on its own, and the untreated depression or anxiety is still there waiting, ready to pull the person back. Treat the mental health condition on its own while active substance use continues, and progress keeps slipping away.
This is the reasoning behind integrated, or dual diagnosis, treatment. Rather than running two separate programmes that barely speak to each other, integrated care manages both conditions together, under one roof, by people who understand how they interact. NIMH describes this approach as combining mental health and substance use treatment so a person receives coordinated care in one place. It tends to hold up better over time precisely because nothing important is left unattended. You can read more about how dual diagnosis treatment in drug rehab works in practice.
The part trauma often plays
For many people, the story starts long before the first drink or drug. A difficult childhood, abuse, loss, violence: experiences that leave a mark the body remembers even when the mind tries to move on. Substances become a way to mute feelings that seem too big to face.
The problem is that numbing is not the same as healing. The trauma does not go anywhere. It waits, and over time it usually gets harder to process, not easier. Trauma-informed therapy, done alongside addiction treatment and at a pace the person can manage, gives someone a safer way to face what happened. The aim is not to erase the past. It is to take away its power to drive the next relapse.
How to recognise co-occurring disorders
Spotting a dual diagnosis is not always straightforward, partly because the signs blur together. Some patterns worth paying attention to:
- Sharp mood swings, calm one day and deeply anxious or low the next
- Pulling away from family, friends and things they used to care about
- Changes in sleep, appetite or energy that do not settle
- Repeated attempts to stop using that keep falling apart
- Using substances mainly to cope rather than to socialise
That last point is telling. When someone tries again and again to stop and cannot, it often means something deeper is driving the use. A proper assessment by professionals who understand both addiction and mental health can untangle what is really going on, which is where treatment should start rather than guesswork.
Treating the whole person, not just the habit
Recovery from co-occurring disorders is about more than stopping the substance. It means tending to the mind, the body and the relationships that addiction has worn down. Good treatment usually blends medical care, structured therapy and practical support for daily life.
At Freeman House Recovery, an inpatient programme of 28 days or longer combines medically-assisted detox, individual and group therapy, psychiatric assessment, trauma counselling and evidence-based approaches such as cognitive behavioural therapy and dialectical behaviour therapy. Alongside these run the quieter supports that help a brain and body settle: yoga, meditation, fitness, time in nature and proper rest. The point of the whole picture is to rebuild a person, not just remove a substance. Detox is only the first step, and going through it safely matters, which is why supervised detox should never be attempted alone at home.
Why reaching out early changes things
The longer a mental health condition and an addiction go untreated, the more tangled they become and the more they cost: relationships, work, health, sometimes years. Reaching out at the first real signs of distress, rather than waiting for a crisis, gives treatment far more to work with.
Early help also protects the things still standing. A job, a marriage, a relationship with children: these are easier to hold onto when the problem is addressed before it has taken everything over. And every honest conversation about mental health, in a family or a community, makes it a little easier for the next person to ask for help instead of hiding.
The support around recovery
Almost nobody recovers from co-occurring disorders alone. Family, friends, counsellors and peers who have walked the same road all play a part. Group therapy offers the relief of being understood by people who get it without explanation. Family involvement helps rebuild the trust that addiction so often damages, which is why family support in addiction recovery matters as much as anything that happens in a therapy room.
Recovery does not end when someone leaves a treatment centre, either. Ongoing therapy, support groups and a relapse-prevention plan keep a person steady through the return to everyday life. Structured aftercare is one of the strongest protectors against relapse, because it keeps support in place exactly when old patterns try to creep back.
Frequently Asked Questions
What is a dual diagnosis?
A dual diagnosis means a person has both a substance use disorder and a mental health condition, such as depression or anxiety, at the same time. The two conditions interact, so treating them together tends to work better than treating either one on its own.
Which comes first, the addiction or the mental illness?
It varies. Sometimes a mental health condition leads someone to self-medicate with substances. Sometimes heavy substance use triggers or worsens a mental health condition. Shared causes like genetics and trauma can also set off both. Treatment does not depend on solving that chicken-and-egg question, it depends on addressing both conditions.
Can co-occurring disorders be treated?
Yes. Both addiction and mental health conditions are treatable health conditions. The World Health Organization notes that effective treatment options exist for mental disorders, even though many people never receive care. Recovery is ongoing rather than a one-time fix, but with the right support people manage both conditions and rebuild stable, meaningful lives.
Why can’t someone just stop using on their own?
When addiction sits on top of an untreated mental health condition, stopping is far harder than willpower alone can manage. Withdrawal can worsen anxiety and depression, and the underlying condition keeps driving the urge to use. Professional, integrated treatment addresses both at once, which is why it holds up better.
Where to find help
If you recognise yourself or someone you love in any of this, please know that struggling with addiction and a mental health condition is not a character flaw. It is a health condition, and it can be treated. You do not have to have it all figured out before you reach out.
In a crisis, the South African Depression and Anxiety Group runs free helplines, including a 24-hour Suicide Crisis line on 0800 567 567 and a Substance Abuse line on 0800 12 13 14. For inpatient dual diagnosis care, Freeman House Recovery offers a private, holistic programme in the Magaliesberg at Hartbeespoort. You are welcome to call us on +27 12 1111 739 or email info@freemanhouserecovery.com for a confidential conversation about what would help. There is no pressure, just a place to start.
