Dual Diagnosis
Useful Links
If you’ve arrived at this page, there is a good chance you’re trying to make sense of something that feels very complicated. Addiction and mental health are both complex areas in their own right, and when the two exist together, it can make the whole situation feel even harder to understand.
You’re not alone in that confusion, as dual diagnosis is one of the most misunderstood areas in addiction and mental health care. Sometimes, it can feel as though the information available feels so clinical that it doesn’t actually help.
On this page, we aim to break down what dual diagnosis really means, why it develops, how it’s assessed, and how it’s treated in the UK.
What does dual diagnosis mean?
Dual diagnosis is a term used when someone is living with both a mental health condition and a substance use disorder at the same time. This means having two diagnoses: a mental health condition and a substance use disorder, also known as co-occurring disorders.
The problem here lies in how they can interact with each other in a bidirectional way. This means that one can exacerbate the other and vice versa, making treatment a lot more difficult than if only one were present.
If you were to be diagnosed with a dual diagnosis, a clinician would need to identify a recognisable mental health disorder alongside a substance use disorder.1
This distinction matters because there needs to be a diagnostic threshold that is met. For example, casual substance use alongside low mood, while something to definitely keep an eye on, isn’t clinically classed as a dual diagnosis. Identifying a dual diagnosis can be challenging because substance abuse often masks underlying mental illnesses.
Clearing up the dual diagnosis literature
If you’ve been reading about this topic online, you may have come across several terms that frequently appear when discussing dual diagnosis. They are:
Co-occurring disorders – Means exactly the same as a dual diagnosis and is one of the most widely used terms in clinical literature.1
Dual disorders – Another term used to describe the co-occurrence of psychiatric and substance use disorders, often used in clinical and research settings.
Comorbidity – This is a wider medical term for any two or more conditions that exist together. It’s accurate but less specific to addiction and mental health settings.
Complex needs – This is another term you’ll run into quite a lot when researching this topic, and it tends to describe people whose needs span across multiple areas. In fact, it doesn’t always need to be mental health or substance use-related; it could also be issues with housing or the criminal justice system. You may see this appear due to how complex issues are heavily linked with substance abuse and mental health issues, meaning the term frequently gets used alongside dual diagnosis. It’s a larger label and doesn’t carry the same clinical precision.
In clinical language, you may also see the term ‘psychiatric disorders’ used to refer to mental health conditions, especially in the context of dual diagnosis.
It’s worth clearing this up before we proceed, because some of these words may be used interchangeably throughout this piece and throughout the internet.
What causes a dual diagnosis?
A common idea amongst many is that one condition simply causes the other. In reality, this idea is less straightforward, in that mental health conditions and substance use disorders share roots that run in different directions.
Evidence suggests that shared risk factors, such as trauma, genetic predisposition, and social isolation, contribute to the development of both psychiatric problems and substance use disorders. Adolescents and young adults are at greater risk for developing co-occurring disorders, as early substance use can interfere with brain development and increase vulnerability to both mental health and substance use issues. Early substance use is a significant risk factor for both psychiatric problems and substance use disorders, especially when combined with traumatic life events such as sexual abuse.
Below, we look at some of the aspects that can cause a dual diagnosis.
The self-medication cycle
One of the most recognised patterns behind a dual diagnosis is the theory of self-medication.3
This is where you begin using a substance to manage symptoms of a mental health condition. For example, alcohol might dull anxious thoughts for a few hours and drugs like cocaine might lift you out of a depressive episode long enough to get through the day. The issue here though is that this relief doesn’t last and the substance in use slowly starts to make the original symptoms worse.3
Take alcohol as an example. It may put a temporary stop to mental health symptoms but it’s still classed as a depressant. When it wears off it can deepen the low mood that you may have been trying to escape from.
Come-downs from stimulant drugs like cocaine can cause rebound anxiety that presents even worse than it was before.
We can see here that what begins as a coping strategy then turns into something that only worsens the situation.
Shared risk factors
Research shows that mental health conditions and substance use disorders share underlying risk factors, meaning both can develop from the same source without one directly causing the other.4
Trauma is one of the most significant, with people who have experienced childhood adversity or abuse carrying a higher risk of developing both.4
Genetic predisposition, chronic stress, poverty, and social isolation all contribute too, which makes mental health conditions more likely to develop and substances more likely to be reached for.
Substances can mimic mental illness
Another complication in dual diagnosis is that certain substances can produce symptoms that look very similar to psychiatric conditions, and this can happen both during intoxication and during withdrawal.
Here are some examples:
Heavy cannabis use has been linked with episodes of paranoia or induced anxiety that resemble psychotic symptoms.5
Cocaine withdrawal can produce depressive symptoms that closely mirror a major depressive episode.
Alcohol withdrawal can cause severe anxiety, and in some cases can lead to hallucinations.
Because of this overlap, it is not always immediately clear whether symptoms are being caused directly by the substance, whether they existed before substance use began, or whether both conditions are present at the same time.
This question becomes central when clinicians begin the assessment process, which is why careful timing and observation are so important when diagnosing dual diagnosis.
Substance-induced vs primary mental health disorders
If you or someone close to you has been assessed for a dual diagnosis, you may have heard the terms “substance-induced” and “primary disorders” being used. Getting the distinction between these two right is one of the most important parts of the diagnostic process, and it’s one that is frequently missed. Psychiatric research interviews are often used to improve diagnostic accuracy in dual diagnosis cases by helping clinicians differentiate between primary psychiatric conditions and symptoms caused by substance use.
Drug dependence can further complicate the differentiation between substance-induced and primary mental health disorders, making accurate diagnosis and effective treatment planning more challenging.
What substance-induced means
Conditions that are referred to as ‘substance-induced’ mean that a mental health disorder has developed as a direct result of substance use. Drug abuse can directly lead to the development of substance-induced mental health conditions. This term can also be used if mental health issues have arisen during intoxication or during withdrawal.6
The examples we covered in the previous sections, like cocaine induced anxiety or cannabis induced psychosis, fall under this category.
Its also worth noting that they differ from primary conditions, in that they have a clear timeline tied to use. In some cases, they’re expected to improve once the substance is removed from the system.
Why assessment timing matters
It’s worth noting that if a person is suffering from a substance-induced mental health condition, the assessment will not take place until a period of abstinence has taken place. This is because the symptoms can closely match those of primary mental health conditions, meaning there’s a real risk of misdiagnosis.
Waiting a period of time gives clinicians time to see which symptoms continue once the chemical effects have calmed down.
Basically, if symptoms are substance-induced, they may resolve once the substance is cleared and the brain has time to stabilise. If they are primary, they are likely to persist and will need their own targeted treatment alongside any addiction support.
When symptoms persist: PAWS and protracted issues
Post-acute withdrawal syndrome, known as PAWS, refers to symptoms that can continie for weeks or months after the acute withdrawal phase has ended.9
Symptoms can include:
Persistent low mood
Anxiety
Sleep disturbance
Difficulty concentrating
Emotional instability
What makes PAWS particularly tricky is that these symptoms overlap heavily with conditions like depression and generalised anxiety. So it can be hard to know whether what you’re experiencing is a lingering withdrawal effect or a primary condition that needs its own treatment.
This is why ongoing clinical review matters so much in dual diagnosis care. A one-time assessment at admission is rarely enough to build a full picture, and treatment plans need to be adjusted as the brain continues to recover. Treatment resistance is common in dual diagnosis cases, as symptoms may persist even after withdrawal, making it more challenging to achieve stable recovery.
Common dual diagnosis pairings
Dual diagnosis can involve almost any combination of mental health and substance use conditions, but certain pairings do appear more frequently in clinical settings. Common co-occurring disorders include various combinations of mental health conditions such as depression, anxiety, bipolar disorder, and schizophrenia, alongside addictive disorders like alcohol dependence, drug addiction, and behavioural addictions.
The prevalence of dual diagnosis is significant, with studies indicating that a large percentage of individuals with mental health disorders also have substance use disorders. Roughly 50% of people with a substance use disorder experience a mental illness at some point.
Below, we take a brief look at the most common ones seen.
Depression and alcohol or drug use
As covered in the self-medication section, alcohol and depression are tightly connected. Depression is a mood disorder, and alcohol use disorder is one of the most common co-occurring conditions seen in dual diagnosis cases. The short-term numbing effect is what draws people in, but the rebound on mood creates a loop that strengthens both the drinking and the depression.10
Stimulants like cocaine can become tied to depression in a different way, with the post-use crash reinforcing compulsive re-dosing as you chase relief from the low that follows each session.
Anxiety and alcohol or benzodiazepines
Alcohol and benzodiazepines both act on the central nervous system in ways that can temporarily reduce anxious feelings. Anxiety disorders are among the most common co-occurring mental health conditions with substance use. The body adapts quickly though, meaning higher amounts are needed for the same calming effect. Withdrawal from both can then produce rebound anxiety that is significantly more intense than the original symptoms.
PTSD and substance use
People living with trauma responses, including flashbacks and hypervigilance alongside persistent sleep disruption, may use substances, like alcohol to dampen these experiences.12 The complication is that substance use can interfere with trauma processing, keeping you locked in a loop where neither condition improves.
Bipolar disorder and substance use
The relationship between bipolar disorder and substance use is well established. Bipolar disorder is a mental disorder that frequently co-occurs with substance use, making dual diagnosis common in these cases. During manic episodes, impulsivity and risk-taking behaviour can lead to heavy drug or alcohol use. During depressive episodes, substances may be used to self-medicate in the same way described earlier on this page.13 This back-and-forth makes bipolar disorder one of the more complex conditions to treat alongside addiction, because mood states can change the pattern of use entirely.
ADHD and substance misuse
ADHD is increasingly being recognised as a risk factor for substance and alcohol misuse, particularly stimulant use. Prescription medications used to treat ADHD, such as stimulants, can themselves be subject to misuse, contributing to dual diagnosis. The link between the two is thought to relate to how ADHD affects impulse control and the brain’s reward system, making substances feel more immediately rewarding.
Psychosis and substance-induced psychosis
This is the most clinically urgent pairing. Psychotic disorders, such as schizophrenia, are often complicated by substance use, which can induce or worsen psychotic symptoms. As outlined earlier, psychotic symptoms can develop during heavy use of cannabis or stimulants, and they require immediate clinical attention.5 Any episode of psychosis linked to substance use should be treated as a medical emergency.
If you or someone around you is experiencing hallucinations, severe paranoia, or a noticeable detachment from reality during or after substance use, call 999 straight away. Acting quickly in these situations can prevent the episode from escalating and ensure the right medical support is in place.
How do I know if I’m suffering from a dual diagnosis?
Recognising a dual diagnosis is not always straightforward, especially when both conditions have been present for a long time. Mental health problems such as depression, anxiety, bipolar disorder, or schizophrenia often coexist with substance use, making recognition and diagnosis more complex. The signs can be easy to rationalise or brush off, particularly if you’re still managing to function at work or maintain relationships on the surface. Some common signs of dual diagnosis include sudden mood changes, withdrawal from family and friends, difficulty managing daily tasks, and changes in sleeping or eating patterns.
Denial is a common issue in both substance abuse and mental health disorders, which can further complicate the recognition of a dual diagnosis.
For you
One of the clearest indicators is noticing that your mental health symptoms get worse during or after substance use. Negative symptoms, such as lack of motivation or emotional flatness, may also worsen in this context, especially for those with severe mental illness. If low mood deepens in the days following drinking, or if anxiety spikes become more frequent alongside stimulant use, that connection is worth paying attention to.
Another sign is using substances specifically to manage how you feel, rather than for social or recreational reasons. This could look like drinking before bed because sleep feels impossible without it, or using cocaine to push through a period of low motivation.
When a substance becomes tied to how you regulate your emotions, it suggests that something deeper is driving the use and that you may benefit from rehab.
For families and carers
From the outside, the signs of a dual diagnosis can be harder to pin down. A pattern worth watching for is when someone repeatedly returns to substance use during periods of emotional difficulty. If every stressful event or low patch is followed by a return to drinking or drug use, that may point toward self-medication rather than recreational use.
When to seek urgent help
If someone is expressing suicidal thoughts, experiencing psychotic symptoms, or going through severe withdrawal from alcohol or benzodiazepines, this should be treated as a medical emergency. Call 999 or attend A&E without delay.
If you are unsure whether a situation counts as an emergency, calling NHS 111 can help you work out the right course of action.
How dual diagnosis assessment works
A good assessment does a lot more than just confirm that two conditions are present. It builds a detailed picture of how they interact and what level of risk you’re currently facing. The assessment process also aims to distinguish between psychiatric illness and symptoms that are induced by substance use, ensuring that the right diagnosis and treatment approach are chosen. Without this level of detail, treatment can end up addressing symptoms in isolation and missing how they feed into each other.
Screening tools used in the UK
Clinicians use validated screening tools to flag where further assessment is needed. For substance use, the AUDIT and DAST are commonly used in both NHS and private settings.
On the mental health side of things, instruments such as the PHQ-9 for depression and the GAD-7 for anxiety help gauge symptom severity early on.16 These tools also assist clinicians in assessing changes in mental state associated with dual diagnosis, ensuring that both mental health and substance use issues are properly identified.
One of the most common gaps in care is when only one side is screened for, with the other overlooked entirely. A thorough screening process catches both.
Clinical history and risk assessment
Beyond screening, a comprehensive assessment reviews the full clinical history. This includes the timeline of both conditions, any previous psychiatric medication, and past trauma.^8^ These details are what help clinicians determine whether symptoms are substance-induced or primary, which directly shapes how treatment is planned.
A formal risk assessment is also carried out, covering suicidal ideation, self-harm history, and vulnerability factors such as unstable housing or domestic abuse.
Safeguarding considerations are also especially relevant if you have dependents or are in contact with children. UK clinical guidance, including NICE recommendations, is clear that these factors must be assessed alongside addiction and mental health needs.
How is a dual diagnosis treated?
One of the most common questions people ask when they first come across the term dual diagnosis is whether both conditions can be treated at the same time. The short answer is yes, and that is the approach that tends to produce the best outcomes. The best treatment for dual diagnosis is one that is tailored to the individual’s specific needs and circumstances. How treatment is sequenced depends on what is happening clinically at the point of admission. Detoxification is often a necessary first step in treating substance addiction in dual diagnosis cases.
When detox comes first
Where the physical risks of withdrawal need to be addressed first, detox becomes the immediate priority. Symptoms that can arise during alcohol detox and or other types of drug detox can be medically dangerous, with seizures and severe physiological instability both being real possibilities.18 Mental health support is still provided during this stage, but the primary focus is on getting through withdrawal safely.
When psychiatric stabilisation is the priority
If you’re experiencing active psychosis or severe suicidal ideation, psychiatric stabilisation takes precedence.19 Clinicians may prescribe medication, including antipsychotic medication, to help stabilise psychiatric symptoms during dual diagnosis treatment. The aim here is to bring you to a place where you’re able to participate in your own recovery safely. These decisions are guided by clinical judgement, with the priority being that neither condition is left unaddressed.
Why integrated treatment works best
Research consistently supports integrated treatment as the most effective approach to dual diagnosis care.20 This means that mental health and substance use are treated within the same programme, by the same clinical team. When treatment is split across different providers, important information can fall through the gaps and an integrated approach removes that fragmentation.
Integrated treatment also heavily relies on evidence-based therapies that are tailored to you and your current situation. Behavioural therapy, including Cognitive Behavioural Therapy (CBT) and Dialectical Behaviour Therapy (DBT), are effective for treating dual diagnosis. Therapies like the ones below are commonly used:
Cognitive behavioural therapy is used to restructure the thought patterns that connect substance use with emotional distress.21
Dialectical behaviour therapy skills can help with emotional regulation
Motivational interviewing supports engagement by helping you connect with your own reasons for change.21
Long-term recovery depends on integrated, ongoing treatment for both conditions, with professional support to address both mental health and substance use disorders together.
UK routes to support
If you’ve read this far and recognise some of what’s been described, knowing where to turn next is the most practical step you can take. Support groups, including Alcoholics Anonymous and specialized dual recovery groups, provide long-term social support for those with dual diagnosis. Group support and social support are crucial for recovery, offering a sense of community and shared understanding. Support groups provide emotional and social support that can be beneficial for individuals in recovery from dual diagnosis.
Accessing treatment for dual diagnosis can be difficult, as individuals may be excluded from mental health services if they admit to substance use problems. Additionally, stigma surrounding mental health and substance use disorders can prevent individuals from seeking help for dual diagnosis.
NHS pathways
Support through the NHS typically begins with your GP, who can make referrals to local drug and alcohol services or community mental health teams.22 You can also self-refer to local drug and alcohol services directly. NHS treatment is usually delivered in the community, with structure and access times varying by area.
Crisis support
As outlined earlier on this page, if someone is in immediate danger through suicidal thoughts, psychotic symptoms, or severe withdrawal, call 999 or go to A&E. For urgent but non-emergency situations, NHS 111 can guide you to the right support.
Private rehab for dual diagnosis
When it comes to private treatment for dual diagnosis, the most important thing is making sure the facility is genuinely equipped to treat both conditions within the same programme. This means clinical staff trained in addiction and mental health care, psychiatric support available on-site, and a treatment plan that addresses both sides from the start rather than treating them separately.20
A CQC-registered rehab centre that can clearly explain how it manages co-occurring conditions is a strong starting point. If a provider can’t answer these questions with specifics, that is worth noting before committing to treatment.
What are the next steps?
At PCP, we understand how difficult it can be to absorb all of this information in one go. This is why we recommend speaking with a specialist who can help turn what you’ve read into something clearer and more manageable.
Our team can talk you through the dual diagnosis treatment options available and answer any questions you may be carrying. From there, a comprehensive assessment helps form a plan that reflects not only your substance use, but the mental health factors influencing it.
PCP provides drug and alcohol treatment services within a safe setting at our CQC-registered facility in Luton, Bedfordshire, supporting people from across the UK. If you’re ready to take the next step, contacting us today can be the moment where things begin to feel steadier and more manageable.
FAQs
Can you treat both conditions at the same time?
Yes. Integrated treatment, where mental health and substance use are addressed within the same programme, tends to produce better outcomes than treating each one separately. Parallel treatment—where mental health and substance use issues are managed independently by different providers—has been shown to be less effective than integrated approaches.
How long does dual diagnosis treatment take?
The length of treatment depends on the severity of each condition and how long they have been present. The priority is always that treatment is guided by clinical need.
Is medication always required?
Medication may be recommended where a mental health condition requires pharmacological management or where withdrawal needs medical support. In other cases, therapy and structured support may be sufficient. The decision is made through clinical assessment and reviewed throughout treatment.
What if the person won’t engage with treatment?
This is a difficult situation for families, but pressuring someone into treatment rarely produces lasting results. You cannot force someone to remain sober, but you can support them in making positive choices and set healthy boundaries to encourage their recovery. Individuals with dual diagnosis face increased rates of relapse, hospitalization, and homelessness compared to those with either disorder alone, making ongoing support even more important. Offering information without forcing a decision and making sure they know support is available when they are ready can all help keep the door open. Remember, long-term recovery requires ongoing support and engagement for the best chance of sustained progress.