Dual Diagnosis Vs Co-Occurring Disorders: What You Need To Know

When comparing the concepts of dual diagnosis vs. co-occurring disorders, it is typical to find that they share more in common than not. For instance, A dual diagnosis case is one in which two distinct psychiatric disorders are diagnosed in the same patient concurrently. The same holds true for co-occurring disorders as well.

Additionally, a dual diagnosis case will include a substance use disorder which is paired with some other type of psychiatric disorder. This holds true for co-occurring disorders, too.

As far as best practices for treatment, there are few, if any, discrepancies with co-occurring disorders vs. dual diagnosis.

Because of these strong similarities, it can become difficult or confusing to discern between the two. However, there is one fundamental concept that makes distinguishing between the two a breeze—the concept of causality.

With dual diagnosis disorders, there is some degree of causality indicated between the two existing conditions—that is, one existed before the other and, in fact, spurred the other into existence to some degree.

This is not the case with co-occurring disorders. While one very may well have developed prior to the other, there is no established causal relationship between the two conditions. The two are deemed independent of each other. It is possible that the two conditions share a similar etiology—developing from the same root cause. But the fact that one did not play a causal role in the development of the other is the key takeaway.

Development Of Dual Diagnosis Disorders

Within the realm of dual diagnosis disorders, there are certain pairs that tend to occur more “naturally” than others, and as a result, they are observed more frequently. There are a couple of factors that tend to contribute to this phenomenon. The first can be explained by examining the concept of Self-Medication.


The concept of self-medication may appear somewhat self-explanatory at a cursory glance. However, by examining it within the context of dual diagnosis disorders, you will find that it is slightly more nuanced than it may first appear. We will start with a definition.

While there is an abundance of colloquial evidence in support of the idea, this hypothesis is derived and examined primarily through clinical observations of patients with diagnosed substance use disorders.

It is hypothesized that self-medication occurs primarily as a way of coping with self-regulation vulnerabilities. The most common of these include:

  • Regulating mood or affect
  • Building or maintaining self-esteem
  • Establishing or maintaining social relationships
  • Physical or psychological self-care

Those with substance use disorder often suffer and become overwhelmed with their feelings, and sometimes seem not to feel emotion at all. This causes great internal distress, and substances of abuse help them by offering relief, helping curb painful mood-states or allowing them to feel emotions that would otherwise be suppressed. Clinical and empirical studies alike support these assertions and maintain that painful effects (moods) and distress are strong determinants in use, dependence, and relapse behaviors.

Most Common Dual Diagnosis Disorders

As you may have gleaned from above, the human brain’s reaction to substances of abuse is not haphazard. It is adaptive, and as such, logical– if unpredictable. This is why we tend to observe patterns in the pairings of dual diagnosis substance use disorders and psychiatric disorders.

The key item to remember when examining these pairs is that, as a general rule in psychopharmacology, the withdrawal symptoms that a given substance produces are equal and opposite to those produced during intoxication. Logically, the disorders that tend to accompany the abuse of these substances follow the similar patterns. Substances of abuse are desirable to those with psychiatric disorders for their ability to alleviate undesirable symptomology. When the substance is absent, those specific symptoms, which often characterize a specific disorder, are what is left.

Heroin and Depression

This pairing is one of the most logical and straightforward, based on the explanation given above. The trademark of heroin is its uncanny ability to produce strong feelings of well-being. It produces an intense euphoria, feelings of relaxation, offers pain relief, and removes anxiety. In a nutshell, heroin abuse provides peace of mind and body.

However, as they say—what goes up must come down. The withdrawal of heroin use is unpleasant, severe, and potentially life-threating. All of the good feelings associated with heroin intoxication are reversed during withdrawal. Feelings of euphoria turn to despondency; well-being turns ill; tranquility becomes angst, and general happiness turns into depression. As the pattern of use and withdrawal continues, the brain will adapt in accordance, and the depressive condition will become continuous and thus diagnosable.

Cocaine and Anxiety Disorders

This relationship, while just as common as heroin and depression, has a slightly different flavor to it as far as causality. Cocaine is a potent stimulant which causes a wide array of effects, both desirable and undesirable, during intoxication.

Some of the subjectively desirable effects include:

  • Euphoria
  • Exhilaration
  • Reduced inhibition

Some of the accompanying undesirable effects are:

  • Insomnia
  • Paranoia
  • Suspiciousness
  • Hallucinations (when taken in higher doses)

Often, during cocaine intoxication, some combination of these desirable and undesirable effects will be experienced. The user may feel energized and excited, yet suspicious of the motives of those around them.

During cocaine withdrawal, the desirable effects that initially balanced out the undesirable ones cease, yet the undesirable ones do not. In fact, they sometimes seem to be magnified. Furthermore, the high that cocaine offers is one of the most short-lived of any drug of abuse. These two factors combine to produce a very unpleasant “come down” in a very short timeframe, which prompts severe cravings and some of the highest rates of re-use of any substance of abuse.

Again, as the rate of use increases, the brain and body begin to adapt. At this point, tolerance begins to develop, and higher doses of cocaine are required to achieve the same high as was experienced previously. In following, the withdrawal symptoms, which so happen to match criteria for an anxiety disorder, increase in intensity and duration—lasting well beyond the timeframe of withdrawal and becoming diagnosable as a dysfunction.

Co-Occurring Disorders

The primary culprit in the development of co-occurring psychiatric disorders is dysfunctional neurophysiology—malfunctions of neurotransmitters, certain brain regions, or neural circuits.

The human brain produces six primary neurotransmitters which it uses to send signals throughout the nervous system, allowing it to control all of our daily functions. The primary neurotransmitters are as follows:

  • Dopamine
  • Serotonin
  • Epinephrine
  • Norepinephrine
  • GABA
  • Acetylcholine

These neurotransmitters each have a unique effect on the neurons they bind to, and thus transmit unique signals which tell different regions of the brain how to react. Depending on which neurotransmitters interact with each brain region, a plethora of different thoughts, moods, and behaviors may be produced.

As we have mentioned, the development patterns of co-occurring psychiatric disorders vary slightly from those of dual diagnosis disorders in that there is no evidence of causality between the two. However, the fact that one did not cause the other does not mean that they are not linked etiologically.

Although it is not necessary in order to be diagnosed as such, many co-occurring disorders share etiological roots—they develop from a similar root cause. This is why, as we have discussed in regard to dual diagnosis disorders, there are distinct trends in the specific pairs of disorders that we observe.

Development Of Co-Occurring Disorders

Now, with so many different functions to carry out on a daily basis, and so few brain regions and neurotransmitters with which to produce them, it stands to reason that each neurotransmitter and brain region is responsible for more than just one function. This is, in fact exactly how the brain works, and here in lies the underlying cause of co-occurring psychiatric disorders.

Sometimes, there is a dysfunction with the production, function, or availability of one of the six primary neurotransmitters which have a cascade effect on brain function. Every function that relies on that specific neurotransmitter to work properly is affected.

Similarly, each part of the human brain serves a specific set of functions in conjunction with the others. These combinations of brain regions are referred to as neural circuits or neural pathways. When one unit of a neural circuit begins to malfunction, it affects the functionality of all of those which it connects to.

Finally, when one of these types of phenomena occurs, it is likely to cause multiple different behavioral issues as a result. When these behavioral dysfunctions reach a certain threshold and become diagnosable according to the guidelines laid out in DSM-V (the diagnostic “scripture,” so to speak), the result is a pair of co-occurring disorders.

Most Common Co-Occurring Disorders

As we have discussed, it is failures of the functional components of the brain, which produce abnormal behaviors that are then diagnosed as psychiatric dysfunction. Because of this, the most commonly paired co-occurring disorders are those that share similar symptomology, or similar abnormal behaviors. Some of the most common pairs are:

  • Anxiety disorder and Major Depressive Disorder
  • Major Depressive Disorder and ADHD
  • Bipolar Disorder and Anxiety Disorder
  • Schizophrenia and Post Traumatic Stress Disorder
  • Post Traumatic Stress Disorder and Anxiety

Each of these pairs of disorders shares common neurochemistry or neurophysiology that produces the common behaviors which define them. It is this underlying common ground that causes them to surface together so frequently.

Finally, when one of these types of phenomena occurs, it is likely to cause multiple different behavioral issues as a result. When these behavioral dysfunctions reach a certain threshold and become diagnosable according to the guidelines laid out in DSM-V (the diagnostic “scripture,” so to speak), the result is a pair of co-occurring disorders.

Treatment For Dual Diagnosis Vs. Co-Occurring Disorders

The most obvious contrast between treatment plans for co-occurring disorders vs. dual diagnosis disorders is that programs for co-occurring conditions will not necessarily include treatment for a substance use disorder. Aside from that, mental health care professionals take a similar approach for treating both.

Historically, it was common for patients to be treated by multiple healthcare professionals, each of who specialized in a specific area of dysfunction. However, more recently, it has become abundantly clear to the healthcare community that this is simply not the most effective structure for treatment.

Anyone in need of treatment for dual diagnosis or co-occurring disorders should seek a team or treatment center that is capable of treating both issues comprehensively and concurrently. This will often involve a combination of cognitive behavioral therapy, psychopharmacology, family therapy, and others in order to ensure that each component of the disorder is treated effectively; biological, psychological, and social.

Effective treatment also requires the will and dedication of the patient to engage with his or her treatment team, and work together to achieve stronger physical and psychological health. This is both a worthy goal and an attainable one.

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1 thought on “Dual Diagnosis Vs Co-Occurring Disorders: What You Need To Know”

  1. This is an excellent post. And the best descriptions of both co-occurring and dual diagnosis I’ve seen yet. It really offered clarity where other definitions and examples did not.

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