co-occurring disorder: what happens when a consumption problem and another mental disorder occur at the same time

There are people who carry two burdens at the same time: that of a consumption that got out of control and that of anguish, sadness or emotional instability that no one has been able to fully explain. Sometimes one condition is opaque to the other. Sometimes the two feed each other. When this happens, we are faced with what is clinically known as "co-occurring disorder" (also called dual diagnosis or dual pathology): the simultaneous presence of a substance use disorder and another mental disorder in the same person.

This article is not intended to diagnose or alarm. What it seeks is to offer clear information about what this coexistence means, why it occurs and what care options exist for those who experience it or for those who accompany someone who experiences it.

What does it mean to have a co-occurring disorder?

The classification systems most used in clinical practice, the Diagnostic and Statistical Manual of Mental Disorders (DSM-5-TR; American Psychiatric Association [APA], 2022) and the International Classification of Diseases (ICD-11; World Health Organization [WHO], 2019), evaluate substance use disorders and other mental disorders as independent categories. When both occur in the same person in a clinically significant way, clinical practice groups them under the term dual diagnosis.

It is a more frequent phenomenon than is usually recognized. The Epidemiologic Catchment Area Study (one of the largest epidemiological studies conducted in this field) found that people with a mental disorder had significantly higher rates of lifetime substance use disorders, and that the relationship was reciprocal: those with a use disorder also had a higher prevalence of other mental disorders (Regier et al. to the., 1990). Data from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) confirmed this trend: the co-occurrence between mood disorders, anxiety disorders, and substance use disorders is high in the general population (Grant et al., 2004).

This does not mean that every person who uses substances has another mental disorder, nor that every mental disorder leads to a substance use problem. What it does indicate is that both conditions coexist frequently enough for any serious clinical evaluation to consider them together.

Why can they coincide? The relationship does not always go in one direction

One of the most frequently asked questions is: which came first? The honest clinical answer is that it is not always possible to determine this and that, in many cases, there is not one-way causality.

There are several models that help understand this coexistence:

-Shared vulnerability: Certain genetic, neurobiological and environmental factors can increase the probability of developing both a mental disorder and a substance use disorder. It is not that one causes the other, but that both emerge, in part, from the same terrain of risk. Chronic exposure to stress, for example, affects brain systems that regulate affect and reward response in ways that may increase vulnerability to both mood disorders and sensitivity to the effects of substances (Brady & Sinha, 2005).

-Self-medication hypothesis: Some people discover, often without being able to name it, that the use of certain substances temporarily relieves symptoms that they find very difficult to tolerate: insomnia, constant anxiety, a feeling of emptiness or a persistently low mood. What works as short-term relief can, however, perpetuate or aggravate the condition over time (Khantzian, 1997). It is not weakness of character; It is a way of regulating a discomfort that has not received another response.

-Effects of sustained consumption on mental health: Chronic use of certain substances can produce or intensify symptoms of anxiety, depression, paranoia or emotional instability. In these cases, distinguishing what is a direct consequence of consumption (and which could be reduced after a period of abstinence) and what corresponds to an independent mental disorder is one of the greatest challenges of clinical evaluation (Brady & Sinha, 2005).

In many cases, the relationship between both conditions is bidirectional: each influences the other in ways that change over time.

What conditions can coexist?

Although co-occurring disorder can involve any combination of diagnoses, some coexistences are more frequently documented in clinical practice:

-Anxiety disorders: Anxiety disorders. Anxiety is one of the conditions that most frequently appears along with a substance use disorder. A person may begin using alcohol or sedatives to calm episodes of distress that they do not fully understand, seeking relief for something that does not yet have a name.

-Depressive disorders: Depression and problematic use of alcohol, opioids or other substances frequently coexist. In some cases depression precedes consumption; In others, sustained consumption worsens depressive symptoms. Identifying the sequence is part of clinical work, although it is not always possible to do so with certainty.

-Bipolar disorder: People with bipolar disorder have significantly higher rates of substance use disorders than the general population (Grant et al., 2004). Periods of intense euphoria or irritability may be associated with increased drinking, while drinking, in turn, may make it difficult to stabilize mood.

-borderline personality disorder (BPD): borderline personality disorder (BPD). The difficulty regulating emotions and impulsivity that characterize BPD may be related to consumption as a way to reduce the intensity of discomfort. Each person experiences it differently, and that variability is part of what makes this diagnosis complex.

-Psychotic disorders: The consumption of certain substances (such as high-potency cannabis or methamphetamines) can trigger or aggravate psychotic episodes in people with previous vulnerability. In turn, some people living with a psychotic disorder may turn to substances seeking to relieve symptoms that have not received enough attention.

-Antisocial personality disorder: Research shows a consistent association between antisocial personality disorder and substance use disorders. The impulsivity, low tolerance for frustration, and difficulty anticipating consequences that characterize this disorder can favor problematic consumption patterns. As in other cases, this does not mean that every person with this diagnosis develops an addiction, but rather that coexistence is clinically relevant and deserves evaluation.

Naming these coexistences does not imply that every person with any of these diagnoses will develop a consumption problem. They are documented patterns in epidemiological research, not rules that automatically apply to each individual.

Why clinical evaluation should consider both conditions

One of the errors that most frequently hinders the recovery process is addressing only one of the two conditions. Treating consumption without exploring the emotional or psychiatric context that sustains it can leave central factors unresolved. Treating the mental disorder without considering consumption can cause treatment to progress slowly or symptoms to reappear as soon as the person faces highly demanding situations.

A rigorous clinical evaluation needs to explore both dimensions: the pattern of consumption, its onset, its evolution and the function it fulfills; but also the emotional history, present or past mental symptoms and the person's life context. A specific challenge is to distinguish, when possible, symptoms that are a direct effect of consumption (and that could be reduced with abstinence) from symptoms that correspond to an independent mental disorder that would persist regardless (Brady & Sinha, 2005).

This process requires time, sustained clinical observation and, in many cases, follow-up that goes beyond the first consultation.

Integrated care: addressing both conditions at the same time

For a long time, the addiction care and mental health systems operated separately, two different doors to what, for many people, is a single experience. The integrated care model arises precisely to close this gap: it consists of addressing consumption disorder and mental disorder within the same therapeutic process, with a team that coordinates its evaluation and intervention (SAMHSA, 2020; Mueser et al., 2003).

This may include individual psychotherapy with approaches that have shown usefulness in dual pathology (such as cognitive-behavioral therapy (CBT) and dialectical behavioral therapy (DBT)), psychiatric follow-up when the condition requires it, support groups with a dual diagnosis perspective, and, in cases that warrant it, a residential or higher intensity treatment phase.

Family support has a significant place in this process. Those around the person are also affected, and can be a real source of support as long as that support is targeted appropriately. Learning about the conditions at hand, setting boundaries that are clear and sustainable, and seeking your own professional guidance when necessary are steps that can make a considerable difference. Family therapy can offer a space to work on these dynamics without the relationship breaking down in the attempt, and respecting at all times the autonomy and process of the person receiving treatment.

Signs that suggest seeking a professional assessment

There is no single threshold that applies to all people equally. However, there are signs that can guide the decision to seek an evaluation:

• Consumption is used repeatedly to calm emotional symptoms (anxiety, sadness, insomnia, intense irritability).
• Emotional symptoms persist or worsen even in periods without consumption.
• The person has tried to reduce or stop consumption without achieving sustained success.
• The mood, behavior or perception of reality present changes that worry the person or those around them.
• Functioning at work, studies or personal relationships has been significantly compromised.

None of these signs is, by itself, a diagnosis. They are indicators that it is worth talking to someone who can evaluate the situation comprehensively.

A path that does exist

Living with a co-occurring disorder (or accompanying someone who does) can be exhausting. But it is also a condition that can be treated, and there are people who achieve significant changes when they receive care that considers everything that is happening, not just part of it.

The first step is often the hardest: acknowledging that something is wrong and seeking an honest assessment. What comes next is not linear or simple. But the path exists, and it does not have to be traveled alone.

*This article is informative in nature and is intended to disseminate evidence-based information about co-occurring disorder. It is not a substitute for an individual clinical evaluation nor does it constitute a treatment recommendation. If you or someone close to you has any of the situations described, I invite you to consult with a qualified mental health professional.*