Eli Snyder1,2, Ryan Nakamura1,2, Miriya Ogawa1,3, Kaylin Bersamin1,4, Kyle Ishikawa2, Hyeong Jun Ahn 3, Enrique Carrazana, MD1, Kore Liow, MD1 Janette Abramowitz, MD1
1Center for Psychiatric Neuroscience, BRAIN Hawaii Pacific Neuroscience, Honolulu, HI, USA.
2John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, USA.
3Department of Quantitative Health Sciences, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI
4 Concussion and TBI Center, BRAIN Hawaii Pacific Neuroscience, Honolulu, HI, USA.
The Role of Pre- and Post-Injury Substance and Medication Use
Introduction
Depression is a common but often under-recognized complication in patients with post-concussion syndrome (PCS) following mild traumatic brain injury (mTBI). While physical and cognitive symptoms of PCS are frequently addressed, clinical strategies for predicting and managing depressive symptoms remain limited.
This blog summarizes findings from a retrospective study that examined whether substance use and antidepressant medication exposure before and after concussion are associated with increased risk of depression in patients diagnosed with PCS.
Background
Post-concussion syndrome can persist long after the initial injury and is associated with a wide range of symptoms, including headaches, dizziness, fatigue, cognitive impairment, and emotional changes. Depression is frequently encountered in this population and can significantly affect recovery, quality of life, and functional outcomes.
Despite its prevalence, there are limited tools available to help clinicians identify which PCS patients are most vulnerable to developing depressive symptoms. Understanding clinical predictors could allow for earlier screening, intervention, and improved patient care.
Study Objective
The primary objective of this study was to determine whether pre- and post-injury use of alcohol, tobacco, marijuana, and antidepressant medications is associated with an increased risk of depression in patients with post-concussion syndrome.
Methods
A retrospective chart review was conducted on 297 patients diagnosed with PCS at a neurology clinic in Honolulu between January 2020 and January 2023.
Key Methodological Details:
- Depression risk was assessed using PHQ-2 scores
- Substance use patterns were reviewed both before and after concussion
- Substances analyzed included:
- Alcohol
- Tobacco
- Marijuana
- Antidepressant medication use was also examined, including continuation or discontinuation after injury
The relationship between these variables and post-injury depression risk was statistically analyzed.
Results
Prevalence of Depression Risk
- 31% of screened PCS patients were identified as being at risk for depression following concussion
Substance Use and Depression Risk
- Pre-injury tobacco use was significantly associated with increased depression risk
- Marijuana use, both before and after concussion, was also significantly associated with higher depression risk
- Alcohol use did not show the same level of association as tobacco and marijuana
Antidepressant Use as a Predictor
- Prior antidepressant use emerged as one of the strongest predictors of post-concussion depression
- Patients who discontinued antidepressant medications after injury were at particularly high risk
- Patients who used both marijuana and antidepressants demonstrated the highest overall risk of depressive symptoms
Clinical Implications
The findings highlight several important considerations for neurorehabilitation and post-concussion care:
- Substance use history should be routinely assessed in PCS patients
- Prior exposure to antidepressants is a critical risk factor that should not be overlooked
- Discontinuation of antidepressant therapy after concussion may significantly increase vulnerability to depression
- Patients with combined marijuana use and antidepressant exposure represent a particularly high-risk group
Recommendations for Clinical Practice
Based on the study findings, the following strategies should be integrated into PCS care:
- Proactive screening for depressive symptoms in all PCS patients
- Regular assessment of substance use before and after injury
- Close monitoring of antidepressant adherence, especially in patients with a psychiatric history
- A coordinated, multidisciplinary approach involving neurology, physiatry, psychiatry, and addiction specialists
Early identification and intervention may improve outcomes by addressing psychiatric symptoms before they significantly impact recovery.
Conclusion
Tobacco use, marijuana use, and prior exposure to antidepressant medications—particularly when antidepressants are discontinued after injury—are key predictors of depression risk in patients with post-concussion syndrome. These findings underscore the importance of integrating psychiatric screening and substance use assessment into routine neurorehabilitation care.
A comprehensive, multidisciplinary approach is essential to identify at-risk patients early and provide timely interventions that support both neurological and mental health recovery.
