Platelet monoamine oxidase activity in children with attention-deficit/hyperactivity disorder
Gordana Nedic1, Nela Pivac, Dubravka Kocijan Hercigonja
1Division of Molecular Medicine, Rudjer Boskovic Institute, Zagreb, Croatia.
Insights
Children with Attention-Deficit/Hyperactivity Disorder (ADHD) show lower monoamine oxidase B (MAO-B) enzyme activity in platelets. This finding suggests MAO-B may serve as a peripheral marker for ADHD subtypes.
Area of Science:
- Neuroscience
- Biochemistry
- Child Psychiatry
Background:
- Attention-Deficit/Hyperactivity Disorder (ADHD) is a heritable neurodevelopmental disorder.
- ADHD is characterized by impulsivity, hyperactivity, and/or inattention.
- Biochemical abnormalities in neurotransmitter systems are implicated in ADHD.
Purpose of the Study:
- To investigate platelet monoamine oxidase B (MAO-B) activity in children with ADHD.
- To determine if MAO-B activity differs between ADHD subtypes and controls.
- To explore MAO-B as a potential peripheral marker for ADHD.
Main Methods:
- Platelet MAO activity was measured using a spectrofluorimetric method.
- Participants included children diagnosed with predominantly hyperactive, inattentive, or combined ADHD subtypes (DSM-IV).
- A control group of children without ADHD was included for comparison.
Main Results:
- Children with all ADHD subtypes exhibited significantly lower platelet MAO activity compared to controls.
- No significant association was found between platelet MAO activity and gender or age.
- Platelet MAO-B activity was consistently lower across hyperactive, inattentive, and combined ADHD subtypes.
Conclusions:
- Lower platelet MAO-B activity is a characteristic finding in children with ADHD.
- This reduced activity supports the hypothesis of MAO-B as a peripheral marker in psychopathology.
- Further research is needed, considering limitations such as the small sample size of girls and the assessment of a single marker.
Abstract:
Attention-deficit/hyperactivity disorder (ADHD) is a highly heritable developmental disorder characterized by symptoms of impulsivity, hyperactivity and/or inattention, and associated with structural and biochemical abnormalities in cortical and limbic structures innervated by dopamine, noradrenalin and serotonin. The enzyme monoamine oxidase, type B (MAO-B), is expressed in platelets, and metabolizes endogenous amines. Its activity has been proposed to represent a peripheral marker of various traits and forms of psychopathology. This study evaluated platelet MAO activity with a spectrofluorimetric method in 72 boys and 12 girls with predominantly hyperactive, predominantly inattentive, and combined subtype of ADHD (DSM-IV criteria), and in 64 control children. The results showed significantly lower platelet MAO activity in children with hyperactive, inattentive, and combined subtype of ADHD than in control children. There was no significant association between platelet MAO activity and gender or age. The limitation of the study was in the small sample of girls with ADHD (N=12), and in the determination of only one peripheral marker. In line with hypotheses of lower platelet MAO activity in different types of psychopathology, children with different subtypes of ADHD had significantly lower platelet MAO-B activity than control children.
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