Prior to 2020, the United States and many other nations were already dealing with a severe pandemic that is only worsening due to COVID-19. Although this pandemic is far more silent than COVID--it is just as deadly and has been ravaging the US for decades. During March, when initial stay-at-home orders were given, online alcohol orders spiked up by 243% (compared to March 2019) and drug overdoses were up 11% in the first three months of 2020 and have continued to rise. On top of this, there has been a decrease in people attending substance abuse therapy and rehabilitation centers due to fear of contracting the virus.
A perfect storm of pandemic-related stress, financial hardship, and social isolation has caused people to depend more heavily on substances to escape exacerbated feelings of depression and anxiety. Why does self-medication seem so appealing right now?
This drug abuse spike can actually be connected to two different talks that we had this semester both related to reward functions in the brain. First, we had Dr. Anna Weinberg talk about how acute stress affects neural responses to rewarding stimuli. The results of her study showed that higher levels of salivary cortisol (a measurement of acute physiological stress) were correlated with reduced neural responses to feedback in the reward-sensitive delta-frequency band. This demonstrated that carrying high levels of stress seems to “numb” our brains’ response to rewarding stimuli. This could very well explain why drug overdoses have seen a sharp upturn during the pandemic. If a person is not receiving the desired rewarding feeling (or dopamine rush) from a specific drug dose, then they will continue to up their dosage until they achieve the desired effect--this vicious cycle inevitably leads to overdose without intervention.
Dr. Stiedl’s talk on optogenetic excitation in mice also points to mechanisms possibly involved in stress-related drug use. His study explored two different fibers within the laterodorsal tegmental area (LDTg), which is related to reward function in the ventral tegmental area (VTA) of the brain. Research has shown that dopamine neurons in the VTA receive additional glutamatergic and cholinergic input from neurons in the LDTg--these two different inputs seem to be involved in processing different aspects of reward.
Using mice models, Steidl and colleagues were able to show the different aspects of reward controlled by these inputs using optogenetic stimulation of the VTA neurons. Results showed that LDTg-cholinergic and LDTg-glutamatergic VTA fibers are equally important in reward function. When the LTDg glutamatergic inputs were excited in the mice, they tended to exit and re-enter the reward chamber more frequently (because stimulation was only given upon entry). Showing that this type of input is important for the reinforcement of reward via entering the chamber. When the cholinergic inputs were stimulated, the mice spent long periods of time in the reward chamber (because stimulation was given as long as the mice remained in the chamber). This showed that cholinergic inputs were crucial for rewarding the mice for staying in the chamber.
Tying this to Dr. Weinberg’s results, it is possible that stress could dampen the aspect of reward mediated by LTDg glutamatergic input. If this is the case, and an individual was not getting the desired effect by first taking the drug (i.e. the buzz wears off too quickly), it would make sense that they would continue to take the drug more and more frequently (analogous to mice exiting and entering the chamber more frequently) to get a semblance of that desired reward response. It is possible that acute physiological stress could also dampen LDTg-cholinergic input as well, making it so that continuous drug effects are weakened, but I believe this effect would still result in more frequent dosages.
In 2017, 8.5 million American adults suffered from both a mental health disorder and a substance use disorder, or co-occurring disorders (Substance Abuse and Mental Health Services Administration, 2018), yet there is virtually no media coverage of this growing problem. A similar trend has been seen with the American opioid crisis as well--tens of thousands of Americans die from opioid abuse each year yet we hear virtually nothing about this in the news. Lack of coverage surrounding overdose deaths makes it seem like overdose is a rare occurrence when it definitely is not. People need to know that it is okay to feel stressed, depressed, and isolated at this time, but self-medication via alcohol and drugs is not the only way to cope. With American COVID deaths surpassing 280,000, it’s imperative that we do everything to protect more lives, including the lives of those struggling with mental illness during this pandemic.
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