THz therapy can be used under various neurological conditions to either ameliorate disease symptoms or rescue disease pathologies, in the same way, that physical therapy dose.
THz radiation has been shown to affect the nervous system, including the structure of nerve cell membranes, genes expressions, and cytokines level.
The nervous system is more vulnerable to exogenous stimuli of THz waves, due to its bioelectric basis of functional activity.
For example, Reukov et al. treated patients with acute ischemia stroke using infrared radiation modulated by THz frequencies (Reukov et al., 2016). THz waves (0.02–8 THz, 2.4 mW/cm2, 22.5 min) were used to stimulate the Bai Hui acupuncture point (crown) on the top of the head, which is one of the most critical areas for regulating neurovascular activity (Wang et al., 2014). Patients in the THz group regained consciousness and resolved neurological symptoms faster than those in the control group.
Improving oxygen delivery in the brain by increasing blood oxygen volume, promoting neuronal rejuvenation are all possible underlying mechanisms for the beneficial outcomes of THz radiation therapy.
In vivo, nitrogen oxides can be resonant with THz waves. Nitric oxide can regulate physiological, pathophysiological, and biochemical processes.
THz radiation primarily interacts with hydrogen bonds in biomolecules (Fischer et al., 2002), creating low-frequency intramolecular vibrations that cause protein structural changes (Cherkasova et al., 2009).
Molecular basis of the impacts of Terahertz radiation on the nervous system
Proteins and nucleic acids are critical components of the nervous system. Low-frequency resonances of biomacromolecules are generated by THz wave radiation, which affects protein spatial conformation and DNA.
In primary hippocampal neurons, the expression of synaptic-related proteins (SYN) was significantly reduced in the group that received THz radiation.
THz radiation at specific frequencies can change the permeability of nerve cell membranes (Cherkasova et al., 2020; Perera et al., 2019).
THz irradiation is thought to cause biological macromolecular interactions that regulate neuronal function.
In terms of neurotransmitter metabolisms, four rat brain regions (hippocampus, cerebral cortex, cerebellum, and brainstem) and three types of neurons-like cells (MN9D, PC12, and HT22 cells) showed significant changes in neurotransmitter content.
Glutamate (Glu) decreased significantly in hippocampal neurons, while alanine (Ala) and glycine (Gly) increased significantly.
Alanine is an amino acid that is used to make proteins. It is used to break down tryptophan and vitamin B-6. It is a source of energy for muscles and the central nervous system. It strengthens the immune system and helps the body use sugars.
Glycine is an amino acid with a number of important functions in the body. Glycine acts as a neurotransmitter, a component of collagen, and as a precursor to various biomolecules (e.g., creatine, heme), among other roles. A few studies have found supplementation with glycine can improve sleep quality, with subsequent benefits to cognitive function. High doses of glycine have been shown to improve symptoms of schizophrenia. Glycine may reduce the blood glucose response to carbohydrate ingestion. People use glycine for schizophrenia, stroke, memory and thinking skills, insomnia, and many other purposes
In excitotoxicity, nerve cells suffer damage or death when the levels of otherwise necessary and safe neurotransmitters such as glutamate become pathologically high, resulting in excessive stimulation of receptors. For example, when glutamate receptors such as the NMDA receptor or AMPA receptor encounter excessive levels of the excitatory neurotransmitter, glutamate, significant neuronal damage might ensue.
Excitotoxicity may be involved in cancers, spinal cord injury, stroke, traumatic brain injury, hearing loss (through noise overexposure or ototoxicity), and in neurodegenerative diseases of the central nervous system such as multiple sclerosis, Alzheimer’s disease, amyotrophic lateral sclerosis (ALS), Parkinson’s disease, alcoholism, alcohol withdrawal or hyperammonemia and especially over-rapid benzodiazepine withdrawal, and also Huntington’s disease.
Glutamate is a prime example of an excitotoxin in the brain, and it is also the major excitatory neurotransmitter in the central nervous system of mammals.
When the glutamate concentration around the synaptic cleft cannot be decreased or reaches higher levels, the neuron kills itself.
Increased extracellular glutamate levels leads to the activation of Ca2+ permeable NMDA receptors on myelin sheaths and oligodendrocytes, leaving oligodendrocytes susceptible to Ca2+ influxes and subsequent excitotoxicity.
In summary, Terahertz has been shown to positively impact brain function and enhance neuronal activity in the brain!