How does lithium help stabilise mood? An introduction to bipolar disorder and circadian rhythms
Lithium, a hugely reactive metal, has entered in to the medical scene in the past 50 years for something rather unexpected. Its one outer shell electron allows it to react violently with substances as common as water due to it being easily oxidised, however through extensive research and clinical trials, it has been found to interact with chemicals in the brain. Perhaps most interesting, it affects a person’s circadian rhythm, leading to its importance medically. Although not fully understood by scientists to this day, it has been used to treat manic episodes in people suffering with bipolar disorder as a mood stabiliser and alternative to valproic acid, and can be taken in conjunction with anti-depressants and other treatments such as psychotherapy. The chemistry behind its reactions in the brain is fascinating, and its efficacy makes it a life-saving drug for many suffering with this mental illness.
Firstly, bipolar disorder, otherwise known as manic depression, is an illness causing unusual mood changes which are more extreme than those occurring in someone without it. The happy or energetic periods are known as manic episodes, and the low energy, down periods as depressive episodes. Bipolar disorder can also affect the ability of a person to think clearly and causes changes in sleep patterns, which of course are otherwise known as circadian rhythms. A human’s circadian rhythm is controlled by the suprachiasmatic nucleus (SCN) or ‘master clock’, a group of about 20,000 nerve cells in the hypothalamus region of the brain. The SCN is connected to the optic nerve at the back of the eye, therefore when light hits the retina in the morning, electrical signals are sent to this portion of the brain and converted into other signals which have a physical effect on the body. For example they induce increases in body temperature, heart rate and blood pressure, along with delaying the release of hormones such as melatonin, responsible for regulating sleep. The chemical mechanism behind this process is far more complex as it involves a Transcription Translation Oscillating Loop. The process of transcription occurs throughout the body, creating a copy of the DNA sequence to form an RNA molecule with the opposite nucleotide bases to form essentially a mirror image. As Adenine and Guanine pair together and Thymine and Cytosine together, if there is an A base on the DNA, a G one will be present on the RNA molecule and this pattern is consistent with the other bases with the exception of RNA containing Uracil bases instead of Thymine. This process occurs as RNA, unlike DNA, can exit the nucleus into the cytoplasm, where the sequence is read and translated into a form of ‘recipe’ for proteins. With regards to a person’s circadian rhythm, core clock genes are involved, and these code for proteins that bind to particular genes on the DNA in order to eit...