Major depression is the most common and serious psychiatric disorder in the world. Recently, the World Health Organization reported that the COVID-19 pandemic has caused a massive increase in the number of people with anxiety and depression. Although there are treatments for depression, about a quarter of patients do not respond adequately to these treatments.
Adjunct Professor Dr. Lim Lee Wei, Principal Investigator and also former Singapore Research Fellow Lee Kuan Yew, reported in 2015 that deep brain stimulation of the animal’s prefrontal cortex could improve memory function and relieve depressive symptoms. These therapeutic effects were attributed to the growth of brain cells in the hippocampus, a brain region that is known to be involved in learning and memory function. However, this technique also known as deep brain stimulation is invasive and requires surgery to implant electrodes in the brain, which can lead to side effects such as infections and postoperative complications.
A team of Hong Kong researchers led by Dr. Lim Lee Wei, Dr. Leanne Chan Lai-Hang and Professor Chan Ying-Shing has been looking for alternative ways to treat neuropsychiatric illnesses. They found that noninvasive stimulation of the corneal surface of the eye that activates brain pathways, resulted in effects similar to notable antidepressants, and also reduced stress hormones in an animal model of depression. This technique called transcorneal electrical stimulation also induced the expression of genes involved in the development and growth of brain cells in the hippocampus.
In related experiments, Yu Wing-Shan and other members of the research investigated whether this approach could also be used to treat Alzheimer’s disease, a common type of dementia without definitive cure. They found that this noninvasive stimulation in mice drastically improved memory performance and reduced beta-amyloid deposits in the hippocampus, which is one of the hallmarks of Alzheimer’s disease.
Associate Professor Dr. Leanne Chan, a senior researcher at CityU and an expert in the electrical stimulation of visual and non-visual brain targets, described this research: “Transcorneal electrical stimulation is a non-invasive method initially developed to treat disease. and it would be a great scientific advance if it could be applied to the treatment of neuropsychiatric diseases ”.
“These research findings pave the way for new therapeutic opportunities to develop new treatment for patients suffering from treatment-resistant depression and dementia, however, clinical trials must be conducted to validate efficacy and safety.” , commented Professor Chan Ying-Shing of HKUMed. and editor-in-chief of IBRO Neuroscience Reports. The application of this non-invasive eye stimulation brings new hopes to people with depression and dementia.
These significant findings were recently published in Brain stimulation i Annals of the New York Academy of Sciences. Yu Wing Shan, who was the principal investigator of these studies, and recipient of the prestigious Hong Kong PhD Fellowship, awarded by the Hong Kong Research Grants Council to the HKUMed Neuromodulation Laboratory (www.drlimlab.com), in col · collaboration with CityU in the Neural Interface Research Laboratory (www.ee.cityu.edu.hk/~lhchan).
References
WS Yu, ACK Tse, L Guan, JLY Chiu, SZK Tan, S Khairuddin, SK Agadagba, ACY Lo, ML Fung, YS Chan, LLH Chan, LW Lim. (2022) Antidepressant-like behaviors by transcorneal electrical stimulation in rat models. Brain stimulation. 15 (3): 843-856.
WS Yu, L Aquili, KH Wong, ACY Lo, LLH Chan, YS Chan, LW Lim. (2022) Transcorneal electrical stimulation improves cognitive functions in aged and 5xFAD mouse models. Ann. NY Acad. Science. DOI: 10.1111 / nyas.14850.
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