• Scientific Evidence
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This is one of the possible organic causes associated with mood disorders. Although it does not occur very often, studies show that people with bipolar disorder are slightly more likely to have experienced head trauma than controls in the general population (source: Surviving Manic Depression, p. 73). More often, studies that examine the association between head injury and psychiatric symptoms document an increased occurence of affective symptoms - that is, depression. This can clearly be due to either a direct brain insult itself, and/or the secondary effects of experiencing and recovering from a traumatic injury.

The degree of head trauma that can result in mood disorders appear to vary – one 1992 review article noted that trauma resulting in mania ranged in severity, including some very mild cases with brief or no loss of consciousness.(McAllister TW 1992). A comprehensive review of environmental risk factors for bipolar disorder (Tsuchiya 2003) concluded that the evidence for head injury as a risk factor for bipolar disorder is "suggestive, but inconclusive."

A letter to the editor of the 2005 edition of the Journal of Clinical Neuroscience (Mustafa et al 2005) documented an increased occurence of mania following head injury (this might be more indicative of a cause of bipolar disorder, since bipolar is distinguished from major depression by the presence of mania), and further noted that the specific area of injury most associated with the onset of mania symptoms is in the right temporal lobe, and the right orbitofrontal cortex. Mustafa 2005 cited two different studies that both found that 9% of patients who experienced a head injury and had a family history of affective disorder secondarily developed mania. This was an increase in mania occurence when compared to other brain damaged populations (for example, patients with stroke).

If a head injury is the cause of mania, it seems most likely to appear within the first five years following the trauma. One study of 490 children (Massagli et al 2004) experiencing traumatic brain injury noted an increased risk for "hyperactivity and psychiatric illness" within the first three years following the incident. Authors calculated a 2x relative risk of any psychiatric symptoms developing after brain injury for children with no previous psychiatric history. Another study of 939 adults with head injury and age-matched healthy controls (Fann et al 2004) concluded that for those experiencing head injury without a prior history of psychiatric symptoms, the greatest risk of affective disorder (note: affective disorder in this case probably means depression, not bipolar disorder) onset was within the first two years (2x increased risk with mild injury, 2-5x increased risk with moderate/severe injury). The risk for developing psychotic symptoms post-injury for those with no previous psychiatric history was 2-3x greater than the control population within first two years for those with a mild injury, and 2-4x greater (significantly greater appearance within the first 18 months following injury) within the first three years for those with a moderate/severe injury.

Remember that the appearance of psychiatric symptoms within a healthy control population is rare to begin with(for example, about 1% of the general population develops schizophrenia or bipolar disorder); therefore, saying that someone with a head injury has a 2-3x greater risk over someone in the general population of developing affective or psychotic symptoms is still a pretty small chance.

In summary, the risk for developing psychiatric symptoms (i.e. mania, affective symptoms, psychosis) following a head injury seem to be:

• Greatest within the first five years following the injury
• Greatest for those who have psychiatric disorders in their family
• Greatest for injuries to the right temporal lobe, or the right orbitofrontal cortex
• Greatest with increasing severity of injury (although symptoms may still occur following mild injury)
• Greater for those who have poor social support during their post-injury recovery (Jorge R et al 2003).

Helpful Actions:

Clearly, any person will avoid sustaining head injuries for their own best interests. However, if you or a relative does experience a head injury, and you know that you have a history of psychiatric symptoms or psychiatric disorders in your family, be aware that you may develop symptoms such as mania, depression, or psychosis. Whether these symptoms will persist or fade as you recover from the head injury is unclear; it seems that those with previous psychiatric history are more likely to experience recurrent symptoms following the injury. For others, the symptoms will be an acute occurence.

Be sure to let any doctor or psychiatrist know of head injuries that you (or your loved one) have sustained within the last five years. It may help with a correct diagnosis and treatment plan.

Making sure that someone recovering from a head injury has good follow-up medical checks, and a good network of social and family support, will both help them achieve the best recovery possible and diminish the likelihood of psychiatric symptoms.

Scientific Studies:

• Secondary mania following traumatic brain injury. J Neuropsychiatry Clin Neurosci. 2005 Winter;17(1):122-4. No abstract available
• Psychiatric illness after mild traumatic brain injury in children. Arch Phys Med Rehabil. 2004 Sep;85(9):1428-34.
• Psychiatric illness following traumatic brain injury in an adult health maintenance organization population. Arch Gen Psychiatry. 2004 Jan;61(1):53-61.
• Mood disorders following traumatic brain injury. Int Rev Psychiatry. 2003 Nov;15(4):317-27. Review.
• Neuropsychiatric sequelae of head injuries. Psychiatr Clin North Am. 1992 Jun;15(2):395-413. Review.