Major depressive disorder (MDD) is a severe mental disorder identified as one of the most common mental illnesses. For 50 years, there has not been a full understanding of the brain’s biology when depression occurs. To reach a conclusive outcome, 86 MDD patients were surveyed, given an MRI/PET scan, and treated with an antidepressant for 8 weeks. From such for my study, the Edinberg Handedness Inventory survey (EHI), PET Scan, and Hamilton Depression Rating Scale (HDS) were utilized to identify patient trends. The first survey used patient responses to determine the laterality of the brain. Out of the 86 patients in the study, 85% were right-handed, implying that analysis of patients would most likely represent those left-brained. With the HDS, each patient was given a number between 0 and +25 based on their response to their moods and habits. If the result was closer to 25, the severity of depression was greater. Based on the patient groupings from the HDS survey, FDG activity was analyzed in the left and right hemispheres of the amygdala. This region of the brain is brought into question due to its activity with MDD. When hyperactive, the amygdala causes .MDD symptoms.

After taking the median of the FDG activity in each group, there was little laterality between each of the hemispheres, but in the right hemisphere, it was observed that the FDG was higher in patients who had an HDS of +25....This revealed that with a severe case of MDD, the .amygdala activity was higher.

References

• Barros, C., Pereira, A. R., Sampaio, A., Bujan, A., & Pinal, D. (2022). Symmetry _ Free Full-Text _ Frontal Alpha Asymmetry and Negative Mood_ A Cross-Sectional Study in Older and Younger Adults. MDPI. https://www.mdpi.com/2073-8994/14/8/1579
• Cowen, 2018. (2018). Cortisol, serotonin and depression_ All stressed out_ _ The British Journal of Psychiatry _ Cambridge Core. Cambridge University Press. https://www.cambridge.org/core/journals/the-british-journal-of-psychiatry/article/cortisolserotonin-and-depression-all-stressed-out/766A58A46F537EA85FB5CB9AEDF33552
• De Crescenzo Franco, Ciliberto Mario, Menghini Deny, Treglia Giorgio, Ebmeier Klaus P, & Janiri Luigi. (2016). Is 18F-FDG-PET suitable to predict clinical response to the treatment of geriatric depression_ A systematic review of PET studies - PubMed. PubMed. https://pubmed.ncbi.nlm.nih.gov/27792402/
• de Kovel, C., Carrion-Castillo, A., & Francks, C. (2019). A large-scale population study of early life factors influencing left-handedness _ Scientific Reports. Scientific Reports. https://www.nature.com/articles/s41598-018-37423-8
• Denny, K. (2009). Handedness and depression_ evidence from a large population survey - PubMed. In PubMed. https://pubmed.ncbi.nlm.nih.gov/19012075/#:~:text=This%20paper%20uses%20a%20new,depressive%20symptoms%20than%20right%2Dhanders.
• Depression_ How effective are antidepressants_ - InformedHealth.org - NCBI Bookshelf. (2020). National Library of Medicine. https://www.ncbi.nlm.nih.gov/books/NBK361016/#:~:text=With%20antidepressants%3A%20About%2040%20to,within%20six%20to%20eight%20weeks
• Edlin, J., Leppanen, M., Fain, R., Hacklander, R., Hanaver-Torrez, S., & Lyle, K. (2015). On the use (and misuse_) of the Edinburgh Handedness Inventory - ScienceDirect. Elsevier. https://www.sciencedirect.com/science/article/abs/pii/S0278262615000044
• Haberling Isabelle. (2017). Cerebral Asymmetries _ SpringerLink. Springer Link . https://link.springer.com/referenceworkentry/10.1007/978-3-319-28099-8_737-1#:~:text=Cerebral%20asymmetries%20refer%20to%20structural,between%20the%20 two%20brain%20hemispheres
• He, B., & Liu, Z. (2008). Multimodal functional neuroimaging_ integrating functional MRI and EEG_MEG - PubMed. PubMed. https://pubmed.ncbi.nlm.nih.gov/20634915/
• Hecht, D. (2010a). Depression and the hyperactive right-hemisphere - PubMed. In PubMed. https://pubmed.ncbi.nlm.nih.gov/20603163/
• Hecht, D. (2010b). Depression and the hyperactive right-hemisphere - ScienceDirect. Elsevier . https://www.sciencedirect.com/science/article/abs/pii/S0168010210001707
• Herholz, K. (2014). Guidance for reading FDG PET scans in dementia patients - PubMed. PubMed. https://pubmed.ncbi.nlm.nih.gov/25391316/
• Hirschman, R., & Safer, M. (1982). Hemisphere differences in perceiving positive and negative emotions - PubMed. National Library of Medicine . https://pubmed.ncbi.nlm.nih.gov/7166043/#:~:text=Two%20experiments%20tested%20 the%20hypothesis,emotions%20by%20the%20right%20hemisphere
• Holland Kimberly. (2023, March 16). Amygdala Hijack: When Emotion Takes Over. Healthline.
• Hong, S.-B. (2023). Brain regional homogeneity and its association with age and intelligence in typically developing youth - ScienceDirect. Elsevier. https://www.sciencedirect.com/science/article/abs/pii/S1876201823000515#:~:text=Regional%20homogeneity%20(ReHo)%20is%20a,level%2Ddependent%20time%20series%20among
• Hopkins, W., Dunham, L., Cantalupo, C., & Taglialatela, J. (2007). The Association between Handedness, Brain Asymmetries, and Corpus Callosum Size in Chimpanzees (Pan troglodytes) - PMC. PubMed Central. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2018751/
• Horan, L. (n.d.). Why Do Left Handed People Have More Sleep Problems_ - The Sleep Matters Club. Retrieved September 29, 2023, from https://www.dreams.co.uk/sleep-matters-club/why-do-left-handed-people-have-moresleep-problems
• Jiang, R., Westwater, M., Noble, S., Rosenblatt, M., Dai, W., Qi, S., Sui, J., Calhoun, V., & Scheinost, D. (2022). Associations between grip strength, brain structure, and mental health in _ 40,000 participants from the UK Biobank - PubMed. In PubMed. https://pubmed.ncbi.nlm.nih.gov/36076200/
• Kustubayeva, A., Kamzanova, A., Kudaibergenova, S., Pivkina, V., & Matthews, G. (n.d.). Symmetry _ Free Full-Text _ Major Depression and Brain Asymmetry in a Decision-Making Task with Negative and Positive Feedback. Retrieved September 29, 2023, from https://www.mdpi.com/20738994/12/12/2118#:~:text=Depressed%20patients%20are%20characterized%20by,of%20which%20may%20be%20lateralized.
• Lee T-S, Quek S Y, & Krishnan K R R. (2014). Molecular imaging for depressive disorders - PubMed. PubMed. https://pubmed.ncbi.nlm.nih.gov/24831591/
• Li, M., Xu, H., & Lu, S. (2018). Neural Basis of Depression Related to a Dominant Right Hemisphere_ A Resting-State fMRI Study - PMC. PubMed Central . https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6008682/
• Li, N., Zhou, R., & Zhang, B. (2022). Handgrip strength and the risk of major depressive disorder_ a two-sample Mendelian randomisation study - PubMed. In PubMed. https://pubmed.ncbi.nlm.nih.gov/36247022/
• Logothetis, N. (2008). What we can do and what we cannot do with fMRI - PubMed. PubMed. https://pubmed.ncbi.nlm.nih.gov/18548064/
• Mayberg Helen S, Lozano Andres M, Voon Valerie, McNeely Heather E, Seminowicz David, Hamani Clement, Schwalb Jason M, & Kennedy Sidney H. (2005). Deep brain stimulation for treatment-resistant depression - PubMed. PubMed. https://pubmed.ncbi.nlm.nih.gov/15748841/
• Medline Plus. (2022). PET scan_ MedlinePlus Medical Encyclopedia. Medline Plus. https://medlineplus.gov/ency/article/003827.htm#:~:text=A%20positron%20emission%20tomography%20(PET,flow%20to%20and%20from%20organs.
• Mundorf, A., & Ocklenburg, S. (2023). Hemispheric asymmetries in mental disorders_ evidence from rodent studies _ Journal of Neural Transmission. Springer Link . https://www.sciencedirect.com/science/article/abs/pii/S1876201823000515#:~:text=Regional%20homogeneity%20(ReHo)%20is%20a,level%2Ddependent%20time%20series%20among
• Neurosci J. (2007). Amygdala reactivity to masked negative faces is associated with automatic judgmental bias in major depression: a 3 T fMRI study. PMC.
• Oldenburg, S., Peterburs, J., & Mundorf, A. (2022). Hemispheric asymmetries in the amygdala_ A comparative primer - ScienceDirect. Elsevier. https://www.nature.com/articles/s41598-018-37423-8
• Packheiser, J., Schmitz, J., Stein, C., Pfeifer, L. S., Berretz, G., Papadatou-Pastou, M., Peterburs, J., & Ocklenburg, S. (2021). Handedness and depression_ A meta-analysis across 87 studies - PubMed. In PubMed. https://pubmed.ncbi.nlm.nih.gov/34298226/
• Park, Y., Jung, W., Kim, S., Hyunjin, J., & Lee, S.-H. (2019). Frontal Alpha Asymmetry Correlates with Suicidal Behavior in Major Depressive Disorder - PMC. PubMedCentral. https://www.mdpi.com/20738994/12/12/2118#:~:text=Depressed%20patients%20are%20characterized%20by,of%20which%20may%20be%20lateralized.
• Stieger, B., Wesseler, Y., Kaiser, S., Sachser, N., & Richter, H. (2022). Behavioral lateralization of mice varying in serotonin transporter genotype - PMC. PubMed Central . https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9875089/
• van der Vinne, N., Vollebregt, M., van Putten, M., & Arns, M. (2017). Frontal alpha asymmetry as a diagnostic marker in depression_ Fact or fiction_ A meta-analysis - PMC. PubMed Central . https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5524421/
• Wendt, T. (2022). The Amygdala_ Your Brain’s Fear Response Center. WebMD. https://www.webmd.com/brain/amygdala-what-to-know#:~:text=This%20means%20that%20if%20your,in%20ourselves%20and%20in%20others
• Zhao, W., Zhu, D., Zhang, Y., Zhang, C., Zhang, B., Yang, Y., Zhu, J., & Yu, Y. (2021). Relationship between illness duration, corpus callosum changes, and sustained attention dysfunction in major depressive disorder - PMC. PubMed Central . https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8250000/
• Zhu, X., Kelly, T., Curry Jr, T. E., & Lal, C. (2015). Altered functional brain asymmetry for mental rotation_ effect of estradiol changes across the menstrual cycle - PMC. PubMed Central . https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4549195/