The Surprising Link Between Bedwetting and Committing Homicide
In 1963, psychiatrist and serial killer profiler J.M. Macdonald proposed a "triad" of factors in adolescence that predict future homicidal behavior. The first two, cruelty to animals and obsession with fire-setting, should come as little surprise, but the third might raise eyebrows: bedwetting.
Macdonald specifically cited bedwetting past the age when most kids grow out of it as being problematic. That's roughly the age of seven.
Macdonald's triad, as the three factors are commonly called, has come under fire over the years.
"Yes, many people who commit homicide as adults had these symptoms as children, but the vast majority of children who have these symptoms do not go on to commit homicide as adults," University of New Mexico neuroscientist and psychopathy expert Dr. Kent Kiehl wrote in his book The Psychopath Whisperer.
University of Kent psychologists echoed this critique in a narrative review published in April. "The empirical research on the MacDonald triad does not fully substantiate its premise. Rather, it would appear that the triad, or its individual constituents, is better used as an indicator of dysfunctional home environments, or poor coping skills in children."
Still, the link between persistent, late bedwetting in childhood and future homicidal behavior endures. Dr. Kiehl thinks there could be a rational explanation for this.
Bedwetting is attributed to developmental delays in the neural circuits of the brain, and occasionally, that deficit is in a region of the brain called the amygdala. The amygdala enhances emotional learning, conditions us to fear, and amplifies stimuli around us. Studies have found connective and structural abnormalities in the amygdalae of criminal psychopaths.
"My hypothesis is that it's the amygdala bladder circuit that is abnormal in youth who go on to commit homicide as adults," Kiehl explained in The Psychopath Whisperer. "If that is the case, we need to revise the Macdonald Triad to indicate that the risk for future violence is present in chronic bed-wetting youth only if the circuit responsible is the one that passes through the amygdala..."