CRIMINALITY

MAO is linked to criminality. Low MAO-B levels can be associated with a high probability of criminal behavior. Most prison populations tend to have lower MAO levels than the general population. However, violent offenders do not seem to have lower levels of MAO than prisoners who have commited non-violent crimes. Crime rates tend to be higher with left and mixed-handers than among right-handers. Studies have found that MAO-B levels are lower among left-handers.

Lee Ellis has stated the following eight behavioral patterns that have been consistently associated with violence and property offending. The first five patterns have been linked to low MAO levels by at least three studies.

Sensation seeking
Impulsiveness and monotony avoidance and job instability
Childhood hyperactivity
Poor academic performance
Recreational drug use (especially excessive use of alcohol)
Defiance of punishment (one study supports low MAO activity)
Extraversion (two studies supportive, one non-supportive, and one supportive for males but not females)
Preference for highly varied sexual experiences or partners (no studies related to MAO activity have been found)

MAO activity is influenced by sex hormones and is lower in males than in females, which may help explain the higher crime rate of males. MAO-B levels hit their lifetime low around puberty and last for the next fifteen years. From about age thirty to eighty, MAO-B activity in both sexes double. This may help account for the age variation in crime.

Could it be possible to prevent further crime using treatment to increase MAO-B levels? Possibly. There are drugs that appear to increase MAO activity, including amphetamines, L-Dopa, corticosteroids, and epinephrine. These drugs may increase MAO levels, but there may also be unknown side effects. It is also possible that low MAO levels are not directly causing the criminal behavior. Something else involved in regulating behavior may be "malfunctioning", causing MAO levels to drop as an inconsequential result. In this case, increasing MAO to normal levels would have no effect.

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