Your article “SLO County ends year with 5 homicides: Mental illness might have played a part in three of the incidents” (Dec. 31) contained careless references to mental illness and violence that seem to imply that illnesses such as schizophrenia and bipolar disorder, in and of themselves, predispose a person to violent behavior.
In fact, increased rates of violent behavior in persons with major mental illness are largely accounted for by other factors, mainly substance abuse and/or anti-social and impulsive personality traits, which are independently associated with increased rates of violent behavior. Other factors contributing to increased rates of violence in persons with and without mental illness include demographic factors such as poverty, low educational level, and exposure to violence in childhood home.
When these various factors are taken into account, there is almost no difference in violence rates between populations with and without mental illnesses such as schizophrenia and bipolar disorder.
With all due respect to Paso Robles police Lt. Ty Lewis, his reference to an “interesting fact pattern” in five cases provides no basis for statistical inference. Lewis is cited as having said that police have discovered that many murder suspects have had a mental condition at some point in their lives. While likely accurate, this comment contributes nothing to our understanding because the same is true for the general population.
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According to the National Institutes for Mental Health, mental illnesses in the form of schizophrenia, mood disorders, anxiety disorders, etc., strike 55 percent of the population over a lifetime, and this does not include substance abuse/dependence disorders. These occur in 14 percent of the general population, according to R. C. Kessler, et al., whose article “Lifetime Prevalence and Age-of-Onset Distributions of DSM-IV Disorders in the National Comorbidity Survey Replication” (World Psychiatry. 2007 October; 6(3): 168–176) reported the results of a study of more than 9,000 adults in the general population who were assessed face-to-face for mental disorders. Kessler concluded in agreement with the NIMH that about half of Americans will suffer from a psychiatric disorder at some time during their lives.
Lewis is cited as having noted that those who commit homicides exhibit extreme behavior, often with psychological factors at play. Homicide is by definition extreme behavior, and surely psychological factors are always at play when one person takes the life of another. These could include jealousy, desire for revenge, etc., but “psychological factors” do not constitute mental illness, especially as a cause of the homicidal behavior.
Regrettably, the casual references in this article to a putative link between mental illness per se and homicide (including in the title) mislead by describing only a bare correlation without the critical “unpacking” required to determine whether mental illness itself is implicated, as opposed to other known risk factors for violence, which occur also in persons without illnesses such as schizophrenic and bipolar disorder.
Incidentally, persons with major mental illnesses are at greatly increased risk for death, illness and injury from all causes: suicide, adverse effects of medication (especially over a lifetime), medical illnesses (for which they may not be able to afford adequate treatment if the illness interferes with regular employment), as well as violence perpetrated against them by others.
As a psychiatrist who has practiced for 30 years, I can assure you that these patients have a hard enough row to hoe without a newspaper, even inadvertently, promoting stigma against them.
Dr. Patricia A. Lipscomb has practiced psychiatry for 30 years. She lives in Nipomo.