Generally, posters presented at conferences seldom get due attention. But a poster authored by 11 scientists from U.S. and two from U.K. at the 54th Annual Meeting of the Society of Nuclear Medicine (SNM) on June 4, this year received well deserved publicity, when Dr Henry N. Wagner Jr., past president of SNM named a brain PET (Positron Emission Tomography) image that showed the correlation between radiotracer uptake and aggressive behaviour in men as the ‘SNM 2007 I mage of the Year.’
Dr Wagner, a specialist physician who has been delivering ‘The Highlights Lectures,’ summarising trends in molecular imaging and nuclear medicine since 1977, chose the image from more than 2,000 studies including scientific presentations and posters from the 2007 meeting at Washington DC.
Brain enzyme levels
Monoamine oxidase A (MAO A) is a brain enzyme. Researchers at the U.S. Department of Energy’s Brookhaven National Laboratory (BNL) showed that healthy men with lower levels of this enzyme exhibited more aggressive personality traits.
The researchers chose normal healthy males with non-violent backgrounds as the subjects and administered the standard, Tellegen and Waller Multidimensional Personality Questionnaire to measure their verbal and nonverbal intelligence, depression, and personality traits (Dotmed.com, June 21). Questions such as whether they frequently lost their temper? Or whether they enjoyed watching violent movies? measured their aggressiveness.
Radiotracer used
The researchers gathered PET scans from each subject using clorgyline, a carbon-11 based radiotracer that binds to brain MAO A and measured the enzyme levels in their brains quantitatively.
More aggressive men had lower clorgyline uptake; less aggressive men had higher uptake. Of the 240 questions, only those about having a short temper, vindictiveness and enjoying violent movies were related to MAO A levels.
They did not find any correlation between clorgyline uptake and depression or negative emotions.
SNM 2007 Image
The SNM 2007 Image of the Year is a series of four images, one providing a view of the human gene with high and low concentrations of MAO A; another, a brain PET scan; and two images of human aggression.
According to Nellie Alia Klein, an assistant scientist at the Brookhaven National Center for Translational Neuroimaging at BNL, the study is an example of how scientists are beginning to investigate the complex relationships between an individual’s biology and his behaviour towards others.
Study of MAO A levels in relation to violent and aggressive behaviour has been a research topic for over two decades. MAO A plays an important role in metabolising neurotransmitters that affect human behaviour, and the gene that regulates MAO A activity has already been associated with aggressive and violent behaviour, Brian Casey quoted Alia-Klein (AuntMinnie.com, June 6)
The study team is indebted to Joanna S. Fowler,an SNM Member, a member of the National Academy of Sciences and a senior chemist at BNL, who developed a method to tag the MAO A enzyme and study its activity in the brain by using a PET camera.
Aggression amount
Interestingly, the amount of MAO A activity in the brain of 27 healthy men corresponded to the amount of aggression, they reported in the questionnaire.
“The less MAO A they had in the brain, the more they answered ‘yes’ to statements about taking advantage of others and causing them discomfort” said Alia-Klein.
“Our findings corroborate the relevance of brain MAO A in aggressive personality’ she clarified. “If this model of understanding is tested on individuals who engage in violent behaviour (such as domestic violence), it should show promise in the future for pharmacological intervention against abnormal violence” Alia-Klein claimed.
K.S. PARTHASARATHY
Former Secretary, AERB
ksparth@yahoo.co.uk
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