About 10 to 20 percent of people suffering from depression meet the diagnostic criteria for treatment-resistant depression. Within the past ten years, scientists have discovered the important role glutamate an amino acid of the central nervous system, plays in mood regulation. Currently, ketamine has demonstrated effectiveness for a major depressive disorder (MDD) and treatment-resistant depression (TRD). However, there are emerging concerns about ketamine’s optimal dose and the frequency of administration.
What is Major Depressive Disorder (MDD)?
Major depressive disorder is debilitating and associated with frequent relapse, persistent psychosocial and functional impairment. MDD is one of the most common types of disability in the world and is associated with an increased risk of suicidal ideations. Traditional antidepressants have no effect on MDD and people aren’t able to recover, then the disorder meets the criteria for treatment-resistant.
What is Treatment-Resistant Depression (TRD)?
Treatment-resistant depression affects more than 1 percent of people in America and approximately 30 percent of all depressed people could fall into this category. TRD is a disabling disorder which is highlighted by psychosocial impairment and poor social outcomes. The pathogenesis of treatment-resistant depression is unknown, and this type fails to respond to two different antidepressant medications given at maximum dose for a period of one month.
How Long Do Antidepressants Take to Work?
Traditional antidepressants usually need a few weeks or up to a month to work and half of all patients don’t respond. The methods used in the past for treating TRD are archaic and some run the risk of causing cognitive impairment. There is an urgent need for improved, faster-acting antidepressant treatments and it is brought home by the fact severe depression can be life-threatening due to an increased risk of suicide.
Does Ketamine Infusion Therapy Work for TRD?
In a preliminary study, medical researchers discovered people suffering from TRD have experienced relief from symptoms in as little as 40 minutes after receiving an IV infusion of ketamine. While the study group was relatively small, it does add to evidence that the class of drugs ketamine belongs to has the potential to be used as a rapid, effective treatment for TRD. Potential side effects of ketamine make it impractical for standard use, but it provides a way to test the drug’s efficacy for treating treatment-resistant depression.
What Role Does Glutamate Play in TRD?
Glutamate is an amino acid of the central nervous system, it has important roles in the body’s physiological processes. The role glutamate plays in the body includes; nerve cell growth, learning and memory, nerve cell damage and death. Glutamate systems play a role directly or indirectly on mood and anxiety disorders, substance abuse, schizophrenia, and various other degenerative neurological disorders. Glutamate is important to the pathophysiology of depression and ketamine infusions provide evidence that future medications with glutamate-modulating activity could be beneficial for people with TRD.
What Age Group is Most Commonly Affected by TRD?
Refractory or treatment-resistant depression can strike someone of any age group. In older adults, depression is the second most common type of psychiatric disorder. Late-life depression, specifically in those age 65 and up, with or without adequate response to any initial antidepressant it can become treatment-resistant depression. The risk factors for late-life depression include:
- Female gender
- Severe physical illness
- Personality type (avoidant, obsessive-compulsive, introverted personality)
- Spousal death or divorce
- Previous episodes of depression
Baby boomers are just as likely as younger people to become depressed. However, TRD in baby boomers stands a better chance of treatment using ketamine infusion therapy, because if it is not covered by insurance these individuals are in a better financial position to pay out-of-pocket for it.
Based on the most recent studies done, ketamine was found to exert a rapid and sustained antidepressant effect on people with TRD. All cases of open-label studies, double-blind randomized placebo or active-controlled studies suggest the active and rapid antidepressant properties of ketamine make it an ideal and promising pharmaceutical for treating TRD and MDD.
Ketamine was found to be a valid option for TRD based on its rapid onset of action, additionally, it is effective in reducing suicidal ideations in MDD patients. Most of the studies done show ketamine is effective when administered in subanesthetic doses, but more study is needed to uncover the drugs long-term effects on treatment-resistant depression.
Ketamine infusion therapy has demonstrated its fundamental and important role in treating TRD patients. Although there is currently limited information available regarding the long-term effects of ketamine, the drug is eliciting interest and studies are ongoing. Future studies should focus on the efficacy of ketamine when compared with other depression treatment options such as combination of antidepressant medications and electroconvulsive therapy or ECT.