Platelet monoamine oxidase activity in association with adolescent inattentive and hyperactive behaviour: A prospective longitudinal study

Platelet monoamine oxidase (MAO) activity is a peripheral marker of central serotonergic activity, and has been associated with psychiatric vulnerability. This longitudinal investigation studied the relationship between aggressive and hyperactive behaviour and platelet MAO activity in adolescents at age 15 and 18 years. The psychological data were obtained from teachers by using the Hyperactivity Scale (af Klinteberg, 1988) and, at the age of 18 years, the teacher-report version of the SNAP-IV. Female subjects had significantly higher platelet MAO activity levels than males, and regular smokers had significantly lower MAO activity levels than nonsmokers. Low levels of platelet MAO and smoking at the age of 15 years were independently associated with Motor Restlessness and Inattention symptoms at the age of 18 years. These longitudinal data suggest that specific aspects of hyperactivity and attention deficit are associated with platelet MAO activity independently of smoking.