Question
What is the prevalence of depression after traumatic brain injury?
Answer
Depression is common after TBI, with about half of individuals experiencing a mood disorder or symptoms of mood disorders post-TBI. These symptoms can be attributed to pre-frontal cortex damage during a TBI, as it is responsible for many executive functions such as attention, flexibility, impulse inhibition, and decision-making.
Additionally, the pre-frontal cortex is involved in emotional responses and is connected to other brain areas responsible for controlling hormones such as serotonin and dopamine. When the pre-frontal cortex is damaged, abnormal functioning can lead to mental health concerns such as depression.
Abnormal function in the pre-frontal cortex may be due to a deactivation of the lateral and dorsal pre-frontal cortexes. These areas control working memory, error detection and correction, and increased activation in the ventral limbic and paralimbic structures, including the amygdala. The amygdala is a structure that regulates emotions such as fear and aggression.
The risk for depression after a brain injury is higher than in the general population, with approximately 25 to 50% of persons with a TBI experiencing major depression within the first year of injury. And over 60% of individuals will experience depression within the first seven years of injury. There is a long-term struggle with mood disorders after a TBI. Healthcare professionals, friends, and families should screen individuals with TBI for depressive symptoms.
Early onset depression seems to have more of a neuroanatomic source. In contrast, later onset is due to the realization that the individual's difficulties are permanent and their life has changed. It is more of a reaction to their deficits. These differences could influence the interpretation of the timing and methods of depression screenings. Early screenings may capture neurobiological sources of depression, but they may miss the later onset depression.
Considering premorbid conditions like addiction, social support, and demographics is essential. If an individual has social support after they experience a TBI, this social support can screen them for depressive symptoms so they can get assessed and treated accordingly. If an individual is experiencing social isolation, they may not have the social supports to screen them for depression, which may go undiagnosed.
Many comorbid conditions are happening simultaneously, including social isolation and changes in personality, lifestyle, and occupation. Therefore, the person's social connections may change.
Spousal and familial concerns are also common after TBI. Individuals may feel socially isolated because of functional changes. For example, they may have differences in cognition and physical status and cannot participate in conversations or social events.
Addiction is a common comorbid issue in individuals with TBI. More than 60% of TBI patients have a history of drug and alcohol abuse after the initial injury for various reasons. This includes trying to self-medicate to reduce their TBI-induced chronic pain or mental health conditions, like escaping from the reality of their diagnosis, especially if the injury happened in a traumatic situation such as a car accident or military service. Using drugs and alcohol may result in the body developing a tolerance for these substances, and withdrawal is complicated because TBI symptoms are exasperated.
Lastly, homelessness is another comorbid condition. More than half of the homeless people or people living in precarious housing situations have had TBI at one point in their life, and this rate exceeds the general population. According to a meta-analysis conducted in Canada and the US, TBI and depression can cause neurological and psychiatric conditions, resulting in homelessness. At the same time, living on the streets can subject an individual to an unsafe environment where assault and aggression are more likely, resulting in a risk for further injuries.
This Ask the Expert is an edited excerpt from the course, Depression After Brain Injury, by Jasleen Grewal, Registered Occupational Therapist, PhD Candidate, University of British Columbia, Julia Schmidt, PhD, BSc (Occupational Therapy).
