Maoa Gene Among Men and Women

In regard to differences between the genders, it is known that men tend to display more boisterous, aggressive, dominating tendencies compared to women who display more caring, nurturing, and affectionate roles. Studies have shown that males are three times more likely to have the MAOA-L variation than women. Predominately, this is because women can be heterozygous or homozygous for the gene, whilst men are hemizygous as they only possess one X chromosome, hence they are automatically at a biological disadvantage (Sabol, Hu & Hamer, 1998).

MAOA Gene in Males and Females

Notably, aggression is not always associated with just men, as high levels of aggression can be seen in females who carry the MAOA-H gene as opposed to men who carry the MAOA-L, as more activity is seen in the male amygdala region (Holz et al., 2014). Additionally, higher hippocampal activation has been associated with the materialization of fear and anger in male MAOA-L carriers and female MAOA-H carriers. This may give further evidence to suggest that negative experiences can provide stimuli for aggressive actions to progress, as this region of the brain is where memories and emotions are heightened (Denson et al., 2009).

Gender-Specific Reactions

Controversially, the MAOA-L genotype has actually been linked to observable happiness in women. A recent study proclaimed this theory, in which women's happiness levels were measured on a 'happiness scale'. The data revealed that women who possessed the MAOA-L gene were happier than those who did not, also no association between men and happiness was detected. This study is yet to be replicated, ergo the accuracy of the experiment cannot be debated (Chen et al., 2013). Conversely, women can suffer from low levels of estrogen during their menstruation period, which is linked to fluctuating MAOA levels causing psychological and emotional stress, and violent probabilities (Staniloiu & Markowitsch, 2012).

Hormonal Influences

A similar occurrence can be seen with high testosterone and low cortisol levels in males, which has been correlated with social aggression. Testosterone and cortisol are both end products contrived in the hypothalamus-pituitary-adrenal axis (HPA) and this neuropathological region of the brain is devoted to motivation and reward-seeking pathways. Hence it can be argued that a high testosterone/low cortisol ratio is a predecessor of threatening and actively seeking risky behaviors (Terburg, Morgan & Honk, 2009). This interplay of hormonal influences highlights the complexity of aggression and emotional responses, suggesting a need for further exploration into gender-specific biological pathways.

Conclusion

Overall, it can be ascertained that continuing research is needed into the female aspect of the MAOA variation as most studies to date have mainly focused on male aggression. Thereupon, clear conclusions cannot be deduced from the evidence available. As our understanding of genetic and hormonal contributions to behavior evolves, it is essential to consider both genders in research to achieve a comprehensive understanding of these complex dynamics.

References

Sabol, S. Z., Hu, S., & Hamer, D. (1998). A functional polymorphism in the monoamine oxidase A gene promoter. Human Genetics, 103(3), 273-279.

Holz, N. E., Boecker, R., Baumeister, S., Hohm, E., Zohsel, K., Buchmann, A. F., ... & Laucht, M. (2014). The impact of MAOA genotype on aggression and empathy in children. PLoS One, 9(3), e92797.

Denson, T. F., Pedersen, W. C., Ronquillo, J., & Nandy, A. S. (2009). The angry brain: Neural correlates of anger, angry rumination, and aggressive personality. Journal of Cognitive Neuroscience, 21(4), 734-744.

Chen, H., Pine, D. S., Ernst, M., & Gorodetsky, E. (2013). The MAOA gene predicts happiness in women. Progress in Neuro-Psychopharmacology & Biological Psychiatry, 40, 122-125.

Staniloiu, A., & Markowitsch, H. J. (2012). The estrogen puzzle in the female brain: Can estrogen help women retain their cognitive function? Journal of Neuroendocrinology, 24(6), 848-862.

Terburg, D., Morgan, B., & van Honk, J. (2009). The testosterone-cortisol ratio: A hormonal marker for proneness to social aggression. International Journal of Law and Psychiatry, 32(4), 216-223.