Depression is a very complex disease. The word depression itself is a blanket term. It can be used to refer to one of the various types of diseases ranging from clinical/ major depression to postpartum depression to Seasonal Affective Disorder. Depression can be caused by a number of physiological and psychological factors and these effects vary from person to person. The exact mechanisms by which depression functions are unknown, however, certain neurotransmitters (chemical messengers that transport information from the brain to the body) have been found to play an important role in certain depression diagnoses. For example, the neurotransmitter serotonin is involved in regulating many bodily functions such as sleep, aggression, and mood. Research has found that inadequate serotonin levels can yield depressive symptoms in certain individuals.
Anti-depressant medications have been one of the leading depression treatments and they work by modulating neurotransmitter levels in the body. Unfortunately, many anti-depressant medications can take weeks before showing positive results and may yield unpleasant side effects such as reduced fertility, loss of effectiveness over time and impaired blood clotting ability.
It has been recently discovered that ketamine, when administered in small doses, helps temporarily suppress depressive moods and has potential to be a future anti-depressive treatment. Scientists have documented ketamine’s ability to curb feelings of depression, elevate patients’ moods within hours and have longer-lasting effects than other anti-depressants. Various researchers are conducting studies to fully understand exactly how and why ketamine works as an anti-depressant, however, we will focus on one study currently investigating ketamine’s activity in a part of the brain called the lateral habenula, to explain why it works so fast.
This study investigates how ketamine affects the lateral habenula, a region of the brain, via N-methyl-d-aspartate synapses. The lateral habenula is a subsection of the habenula, containing reward-negative neurons. Excessive neuronal firing (known as burst firing) in the lateral habenula is known to lead to depressive feelings. N-methyl-d-aspartate is a biological molecule necessary for lateral habenula neuronal firing. Ketamine has the ability to block the NMDA sites, thus reducing the burst firing in the lateral habenula and depressive feelings. This first study was conducted on two groups of rats, one group of genetically-induced depressed rats and a control group of non-depressed rats. It was noted that the lateral habenula of each of the depressed rats showed burst firing and resultantly, additional NMDAR activity. Once the ketamine was administered, the genetically-induced depressed rats began to act like the non-depressed rats in the control group.
As stated earlier, there is still tons of research that must be conducted to determine if ketamine can become a regular treatment option for depression. There is much controversy over the ethics and safety concerning the drug’s usage, given its reputation as a party drug, but the appropriate authorities are currently investigating these concerns.
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