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How Mental Health Comorbidities Impact Diagnosis and Treatment

What is comorbidity?

As different types of chronic illnesses are beginning to arise, so are the possibilities of gaining comorbidity. Comorbidity is the “co-occurrence of 2 or more chronic health conditions,” [1]. It often comes in the form of either medical or mental disorders, and it has been reported that some may contract both a mental and medical disorder at the same time. This can happen naturally, or with the aid of substance abuse or social disadvantage. It is also reported that “mental disorders may precipitate the onset of physical conditions” because they can lead to physiological stress, and it can also go the other way around where medical conditions can cause patients to develop emotional and mental stressors [1].

Either way, comorbidity can cause three major shifts that can be seen within clinical practices. One is that the frequency of comorbidity is increasing. Two is that this increase makes it harder to detect and treat the original disorder, which can make successful treatment outcomes become lower. Third, comorbidity can cause the original disorder to amplify quicker, which means that symptoms can be recognized earlier on. It becomes a lot trickier to diagnose someone when they are displaying symptoms of multiple disorders, and this, often, can lead to getting the wrong treatment. Below, we will discuss some disorders that can greatly be affected by comorbidity.

Comorbidity Within Social Anxiety Disorder

“Occurring in as many as 90% of patients” with social anxiety, comorbidity can affect the diagnosis of a patient, further throwing off how they are treated by medical professionals [2]. Social anxiety disorder (SAD) is defined as “persistent and marked fear/anxiety about one or more social or performance situations in social settings,” [2]. This can negatively affect a person’s ability to function within “social activities, relationships, work, and academic functioning,” [2].

It is common for SAD to first become present during adolescence, and it can grow from there if not treated properly. This correlates with the fact that SAD often develops within a person before a comorbid disorder does. Often, this comorbid disorder can develop as “subsequent major depression (MD) and alcohol use disorder (AUD),” [2]. Developing these additional disorders can cause patients with SAD to have “increased symptom severity, treatment resistance, and decreased functioning (such as missed days at work or dropping out from school), and they also have higher rates of suicide when compared to ones without comorbidity,” [2].

These increases in symptoms can make it harder for clinicians to properly diagnose their patients. Therefore, these professionals can either fail to notice the comorbid symptoms, or they could interpret the patient’s heightened symptoms as resistance to what may be an inadequate treatment.

Comorbidity With Borderline Personality Disorder

Bipolar personality disorder (BPD) can be recognized as “a 1-year pattern of immature personality development with disturbances in at least five of the following domains: efforts to avoid abandonment, unstable interpersonal relationships, identity disturbance, impulsivity, suicidal and self-mutilating behaviors, affective instability, chronic feelings of emptiness, inappropriate intense anger, and stress-related paranoid ideation,” [3]. Those with BPD can be diagnosed as early as eleven years old.

There are three components of BPD that can be observed, including “an interiorized component (identity disturbance, stress-related paranoid ideation, chronic feelings of emptiness, and efforts to avoid abandonment), an emotional component (affective instability and inappropriate, intense anger), and an externalized component (impulsivity, suicidal and self-mutilating behaviors, and interpersonal relationships instability),” [3].

In some cases, BPD and SAD can be seen together in one person. Although the change of this happening only goes up to 21%, it is still important to note. It has been observed that among these patients there are “higher symptom severity, higher rates of other anxiety disorder comorbidities, and lower functioning than those without mood disorder comorbidity,” [3].

Comorbidity Within Attention Deficit Hyperactivity Disorder

Attention deficit/hyperactivity disorder (ADHD) is often paired with substance use disorders (SUD), usually beginning at an early age. It is noted that these patients with ADHD and SUD “show more complex and chronic patterns of substance use, including more poly-substance use, than adults with SUD without comorbid ADHD,” [4].

Adults with ADHD and SUD are at risk of being misdiagnosed, or underdiagnosed. According to previous texts, ADHD had to be diagnosed separately from other disorders. SUD can also cause adult patients to forget or have trouble remembering past symptoms of ADHD. It is often shown that “if an individual with SUD was not diagnosed with ADHD as a child, it is less likely that the behavior as an adult will be linked to ADHD because these are associated with intoxication, withdrawal or the (interpersonal) consequences of substance abuse,” [4].

It is important when getting diagnosed with ADHD, to go to a knowledgeable and competent diagnostician. The diagnostic process should start soon, but also when the patient is not within a phase of heavy intoxication or heavy withdrawal.

Comorbidity With Depression

Depression is a mental disorder that is “frequently accompanied by other mental disorders and various somatic diseases,” [5]. Major depressive disorder (MDD) is named “one of the most common mental disorders worldwide,” [5]. MDD is often seen with anxiety disorders and SUD. As discussed before, mental disorders can provide a gateway to physical disorders, and this is often the case with depression. Some of these disorders that can stem from depression include “diabetes, cardiovascular disease, hypertension, chronic respiratory disorders, and arthritis,” [5]. This is a result of the symptoms of depression, which can lead to “poor quality of life, worse course of the physical disorder, higher functional impairment and disability, increased service utilization and higher medical costs, and increased mortality compared to the presence of either depression or the physical disease alone,” [5]. This can be revealed as “diseases of the central nervous system (i.e. multiple sclerosis) and several neurological diseases, among them sleep disorders, migraine and epilepsy, most of them exhibiting at least 2- to 3-fold higher prevalences in depression,” [5].

Comorbidity Within Chronic Migraine

Chronic migraine (CM) is probably not one of the first disorders that you think of, and it is not as prevalent as the other disorders mentioned above. This neurological disease “can be episodic (EM; <15 headache days/month) or chronic (CM; ≥15 headache days/month for >3 months),” [6].

Chronic migraine is often comorbid with depression and anxiety. The combination of comorbid depression and anxiety linked with chronic migraines can lead to “reduced quality of life and increased overall disease burden, and can make migraine treatment more challenging,” [6]. Both episodic and chronic migraines can cause disturbances in sleep, as well as fatigue. Both episodic and chronic migraines can cause disturbances in sleep, as well as fatigue. Treatments are being studied that can potentially “reduce psychiatric comorbidities, improve sleep quality and reduce associated fatigue symptoms,” [6]. One example of this is “onabotulinumtoxinA 155 U was found to be safe and effective for chronic migraine treatment over 108 weeks, reducing headache day frequency and HIT-6 scores in people with chronic migraines regardless of the presence of symptoms of comorbid disease,” [6].

Comorbidity is not as uncommon as we may think. Often, it can be seen in those with mental disorders such as social anxiety disorder, borderline personality disorder, attention deficit hyperactivity disorder, depression, and those with migraines. It is important to seek treatment if you have any of the symptoms mentioned in this article, as these disorders can later become comorbid.


1. Walker, E. R., & Druss, B. G. (2016). A Public Health Perspective on Mental and Medical Comorbidity. JAMA, 316(10), 1104.

2. Koyuncu, A., İNce, E., Ertekin, E., & Tükel, R. (2019). Comorbidity in social anxiety disorder: diagnostic and therapeutic challenges. Drugs in Context, 8, 1–13.

3. Guilé, J. M., Boissel, L., Alaux-Cantin, S., & Garny De La Rivière, S. (2018). Borderline personality disorder in adolescents: prevalence, diagnosis, and treatment strategies. Adolescent Health, Medicine and Therapeutics, Volume 9, 199–210.

4. Crunelle, C., Van Den Brink, W., Moggi, F., Konstenius, M., Franck, J., Levin, F., Van De Glind, G., Demetrovics, Z., Coetzee, C., Luderer, M., Schellekens, A., & Matthys, F. (2018). International Consensus Statement on Screening, Diagnosis, and Treatment of Substance Use Disorder Patients with Comorbid Attention Deficit/Hyperactivity Disorder. European Addiction Research, 24(1), 43–51.

5. Steffen, A., Nübel, J., Jacobi, F., Bätzing, J., & Holstiege, J. (2020). Mental and somatic comorbidity of depression: a comprehensive cross-sectional analysis of 202 diagnosis groups using German nationwide ambulatory claims data. BMC Psychiatry, 20(1).

6. Blumenfeld, A. M., Tepper, S. J., Robbins, L. D., Manack Adams, A., Buse, D. C., Orejudos, A., & D Silberstein, S. (2019). Effects of onabotulinumtoxinA treatment for chronic migraine on common comorbidities including depression and anxiety. Journal of Neurology, Neurosurgery & Psychiatry, 90(3), 353–360.



Author: Kayjah Taylor

Editor: Lauryn Agron

Health scientist: Dora Sow

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