Are mentally ill people more likely to be violent? That is certainly the impression you could get from media reports, crime shows and the exaggerated stories of some. A typical horror story often begins with a ‘mentally unstable’ individual launching into a series of heinous violent crimes.
Although these kinds of stories chill our blood on a hot day, they do not actually represent the facts. I have mentioned in past columns that the mentally ill are in reality more likely to be the victims of violent crime than the perpetrators.
One study out of Sweden sought to definitively answer this issue when it comes to individuals with bipolar disorder – one of the illnesses characterized by shifts in mood states between the lows of depression and the reckless, agitated highs of mania. Some feel this condition is likely to contribute to violence.
In this study, researchers gathered comprehensive, population-wide data by analyzing hospital discharge records between 1973 and 2004. They compared the data of 3,743 individuals diagnosed with bipolar disorder on at least two occasions with over 37,000 unaffected people from the general population and just over 4,000 unaffected full siblings.
Information was cross-referenced against a database of convictions for violent crimes in that country. The prevalence of violent crime was 8.4 percent for patients, 3.5 percent for the population controls and 6.2 percent for siblings. When adjusted for relevant demographic factors, the odds ratio for patients was 2.3 compared with the population and 1.6 compared with siblings.
The interesting part of this study is that patients who did not have co-existing substance abuse also did not have a significantly increased likelihood of violence. When the data was analyzed while only comparing those with substance abuse to the controls, the odds ratios were much higher – 6.4 compared to the population and 2.8 compared to siblings.
Similarly, when the population and sibling control groups were analyzed based on their own substance abuse, the rates of violent crime were much higher – 33 percent for the general population and 42 percent for the sibling group.
So – although bipolar disorder does involve the manic mood state with impulsive behaviours, recklessness and feelings of agitation, the real danger for increased violence is associated with substance abuse rather than the mood state itself.
That said, substance abuse is much more common among individuals with bipolar disorder than it is in the general public.
Substance abuse screening and assessment is an important part of the ongoing treatment of anyone with a psychiatric problem. Many people try to self-medicate with drugs or alcohol and these can do a lot of harm – making symptoms of the disorder worse and can even increase the likelihood of violence in some patients. When there is a substance abuse issue co-existing with a mental illness, it is critical to deal with both issues.