Introduction

Schizophrenia is a multifaceted and challenging disease that is further compounded by the presence of various comorbidities. It is one of the most disabling psychiatric disorders that patients may experience, and it affects more than 3.2 million people in the United States. The economic burden of schizophrenia is approximately $155.7 billion per year.1 

Psychiatric Comorbidities

The top 3 most common psychiatric comorbidities in patients with schizophrenia are:

  • Depression: Affects 50% of patients with schizophrenia2  
  • Substance use disorder: Affects 47% of patients with schizophrenia2
  • Anxiety disorders: Includes panic disorder (15%), compared to 2.0% to 5.1% in the US general population,2 obsessive-compulsive disorder (OCD; 23%), compared to 2.3% in the US general population,2,3 and posttraumatic stress disorder (PTSD; 29%), compared to 7.8% in the US general population.2

These comorbidities significantly complicate the treatment and management of schizophrenia, necessitating a comprehensive and integrated approach to patient care. A recent study by Lu et al analyzed large-scale real-world data to identify comorbidity patterns in patients with schizophrenia. The study found that anxiety, PTSD, and alcohol and substance use disorders were significantly more common in patients with schizophrenia before their diagnosis.1

Impact of Psychiatric Comorbidities

Most psychiatric comorbidities have been shown to negatively influence patient outcomes. The presence of depressive symptoms in patients with schizophrenia is associated with diminished quality of life, poor functioning, and increased risk of suicide, psychotic relapse, and psychiatric hospitalization.4,5 Substance abuse disorders in patients with schizophrenia have been implicated in worsening positive symptoms, increased risk of psychotic relapse, and poorer physical and mental health.2 Comorbid anxiety disorders are linked to worse initial outcomes in first-episode psychosis, while OCD and PTSD have been associated with more symptoms and worse functioning.5 individuals with psychiatric and physical comorbidities are believed to have worse symptoms and greater functional impairment compared to the general population.6

Treatments

Given the negative impact of these comorbidities on patients, it is crucial to manage them effectively. It has been suggested that symptoms of depression, anxiety, and OCD reflect different subtypes that may underlie the pathogenesis of schizophrenia.4 Clinicians can personalize interventions based on individual patient characteristics with the recognition that there may be subgroups with differing responses to comorbidities. Treatment strategies may include adjusting medication regimens, incorporating targeted psychotherapy, or addressing specific comorbid conditions to improve remission outcomes.5

Conclusion

People with schizophrenia often have comorbid medical and psychiatric comorbidities that contribute to disparities in morbidity, mortality, and social and occupational functioning.6 Managing these comorbidities is vital for improving patient outcomes and quality of life. Properly addressing these coexisting conditions can enhance remission rates and significantly uplift the lives of individuals with schizophrenia.

References:  

  1. Lu C, Jin D, Palmer N, et al. Large-scale real-world data analysis identifies comorbidity patterns in schizophrenia. Transl Psychiatry. 2022;12(1):154. doi:10.1038/s41398-022-01916-y  
  2. Buckley PF, Miller BJ, Lehrer DS, Castle DJ. Psychiatric comorbidities and schizophrenia. Schizophr Bull. 2009;35(2):383-402. doi:10.1093/schbul/sbn135 
  3. Obsessive-compulsive disorder (OCD). National Institute of Mental Health. Accessed October 25, 2024. https://www.nimh.nih.gov/health/statistics/obsessive-compulsive-disorder-ocd 
  4. Abdullah HM, Azeb Shahul H, Hwang MY, Ferrando S. Comorbidity in schizophrenia: conceptual issues and clinical management. Focus. 2020;18(4):386-390. doi:10.1176/appi.focus.20200026  
  5. van Dee V, Kia SM, Winter-van Rossum I, Kahn RS, Cahn W, Schnack HG. Revealing the impact of psychiatric comorbidities on treatment outcome in early psychosis using counterfactual model explanation. Front Psychiatry. 2023;14:1237490. doi:10.3389/fpsyt.2023.1237490  
  6. Rosenfeld LC, Wang P, Holland J, Ruble M, Parsons T, Huang H. Care management of comorbid medical and psychiatric illness: a conceptual framework for improving equity of care. Popul Health Manag. 2022;25(2):148-156. doi:10.1089/pop.2021.0366