The prevalence of opioid addiction is on the rise. Opioid related overdoses were responsible for over 42,000 deaths in 2016, which is more than ever before (“Public Affairs”, 2018). Opioid addiction is continuously being studied to develop more effective treatment programs and to examine the impacts of long-term use on the nervous system. Drug addiction is when the individual has awareness of the harmful effects that the substance has on his or her daily life but continues to use the drug anyways (Gould, 2016). Opioids affect executive function, the limbic system, decision-making, biological aging, cognitive decline, and neurotransmitter release (Cheng et al., 2013; Müller et al., 2018). Some effects are seen after short-term use while others are seen after long-term use (“What are opioids”, 2018)
Opioids are drugs that bind to the opioid receptors of cells in the central nervous system to block the feeling of pain (“How Drugs Affect the Brain”, 2018). Common examples of opioids include fentanyl, oxycodone, morphine, methadone, and heroin (“Opioid (Narcotic) Pain Medication”, n.d.). Opioids increase the amount of dopamine released in the brain, which is the neurotransmitter responsible for creating the feeling of pleasure (“Dopamine”, n.d.). Dopamine is also responsible for executive functions such as attention, which can be impacted by abuse use of opioids (“Dopamine”, n.d.). Detrimental effects occur as the brain develops a tolerance to the opioids interacting in the central nervous system (“How Drugs Affect the Brain”, 2018). Quitting the use of opioids is difficult due to the undesirable effects of withdrawal as dopamine levels decrease when the opioids wear off (“How Drugs Affect the Brain”, 2018).
Routine use of opioids results in long-term effects to the brain (“How Drugs Affect the Brain”, 2018). Significant effects may occur because of the decrease in overall cognitive function, due to the damage of the dorsolateral prefrontal cortex (Cheng et al., 2013). Other impacts of opioid use involve a decrease in size of the hypothalamus, which is a part of the limbic system that is responsible for how the body responds to stress (Müller et al., 2018). Drug addiction is often viewed as only affecting an individual or a community. However, the following research demonstrates the importance of reviewing how routine use of opioids can effect structural and cellular changes in the brain. Regular use can lead to decrease in cognitive function, increase in cellular aging, and decrease in hypothalamic volume (Cheng et al., 2013; Müller et al., 2018).
A study reviewed how opioid use, specifically heroin, influences biological aging at the level of the cell (Cheng et al., 2013). The enzyme telomerase was examined through the extraction of a blood sample. The researchers reported that telomerase is a common marker of stress and serves as a link between aging-related diseases. Telomeres protect the endings of chromosomes and if the chromosomes are uncovered, damage to DNA may occur as well as the aging process may begin earlier. The effects of heroin use at the cellular level and the level of the structures of the brain were being examined. The structures examined include the prefrontal cortex and the medial temporal lobe, which have both been studied previously in relation to the aging process. Damage to the prefrontal cortex has shown an impact on cognition. In other various studies the link between damage to the prefrontal cortex and the medial temporal area due to heroin use has resulted in impairments to both the structure and role that the areas carry out (Cheng et al., 2013).
There were 63 total participants, including 33 heroin users and 30 healthy controls (Cheng et al., 2013). The 33 participants that were self-reported heroin users were volunteers from two different treatment centers. Participants were reportedly not receiving any medical treatment at the time of the study and specifically reported heroin was used for majority of drug use (over 50% of the time). To compare intelligence between the heroin users and healthy controls the researchers administered the Raven’s Progressive Matrices assessment and the Hospital Anxiety and Depression Scale. To evaluate telomerase activity in the participants a blood sample was taken and measured based on previous approved protocol seen in other research studies. The participants also had an MRI completed to analyze the structures of the brain hypothesized to be impacted. Participants also underwent an fMRI scan while awake. Results from both the MRI and fMRI were combined with years of education of the participant and results from the Hospital Anxiety and Depression Scale in order to increase the accuracy of the findings. The cognitive areas assessed in the study were executive functioning, attention, working memory, learning and memory, and visuospatial skills. All areas of cognition were assessed based on standardized measures of assessment (Cheng et al., 2013).
The results demonstrated that telomerase activity was lower in heroin users compared to healthy controls (Cheng et al., 2013). The researchers found that heroin users have smaller amounts of dorsolateral prefrontal cortex grey matter, which correlated with smaller amounts of telomerase activity. The results determined that the structure and function of the right dorsolateral prefrontal cortex, and telomerase activity were impacted due to heroin use in comparison to the control group. The researchers primarily focused on the link between the dorsolateral prefrontal cortex and three other areas of the brain. Other structures examined consisted of the left orbitofrontal cortex, right entorhinal cortex, right superior occipitoparietal cortex, and bilateral anterior cingulate cortex. All the connections between the previously mentioned areas and the dorsolateral prefrontal cortex were negatively impacted due to heroin use. The results confirmed the hypotheses that heroin abuse correlates with low telomerase activity, which results in biological aging. Heroin abuse also decreases the ability for the dorsolateral prefrontal cortex to interact with other areas of the brain that are also related to aging. Lower telomerase levels and damage to the dorsolateral prefrontal cortex are what speed the aging process and explain why higher level of cognition is affected for individuals who abuse heroin, similarly to aging adults (Cheng et al., 2013).
The following study was conducted to examine the effects of routine heroin abuse affects the hypothalamus (Müller et al., 2018). The hypothalamus is primarily responsible for how the brain processes stress. Specifically, the researchers focused on how the size of the hypothalamus structure changed due to heroin use. The researchers examined the postmortem brains of 14 heroin abusers that died due to overdose and 12 non-heroin users that died due to other various causes unrelated to substance abuse. The mean age of the 14 brains affected by heroin was 30.8 and the mean age for the 12 controls was 44.4. The results demonstrated that heroin users had increased total brain volume compared to the control group due to young age. A neuropathologist and a forensic pathologist examined all of the brains. Additionally, a toxicology test was run to determine other substance abuse. The researchers then examined each brain by making cuts anterior to genu of the corpus callosum and posterior to splenium of the corpus callosum. The brain cuts were put into wax and secured. The overall volume decrease before and after mounting the brain tissue was examined. The tissue of the hypothalamus was then stained and measured based on the distance between the sections and multiplied by the transverse cuts made to each brain. The researchers considered the size of the tissue prior to making adjustments to the brain as well as the size of the hypothalamus in comparison to the entire brain in order to make the results an accurate representation (Müller et al., 2018).
The volume of hypothalamus compared to the total brain volume was smaller in the brains of heroin addicts than control group members (Müller et al., 2018). The left hemisphere hypothalamus volume was 20% smaller in the brains of heroin addicts in comparison to the control group. The results assist in guiding further research when examining what long-term effects occur to the brain of someone who abuses heroin, or opioids. The results not only demonstrate that an impact was made on the size of the hypothalamus but that function of the hypothalamus is impacted as well. The results indicate that the hypothalamus is affected in individuals who are addicted to opioids, which leads the researchers to believe that further research is necessary (Müller et al., 2018).
Opioid addiction is dangerous for many reasons, specifically to physical and biological health. Opioid abuse, specifically heroin, affects both the areas and functions of the different structures in the brain from being able to carry out designated responsibilities (Cheng et al., 2013). The research previously reviewed only begins to examine how opioid addiction affects structures of the brain and how the nervous system is affected at the cellular level (Cheng et al., 2013). Research with opioid addicted individuals can be difficult due to the limited amount of participants that are willing to volunteer for research; therefore the sample size for opioid addiction research is typically small (Müller et al., 2018). The results from Cheng et al. (2013) and Muller et al. (2018) are both statistically significant and clinically significant. The implications from both studies indicate that routine use of heroin will result in unfavorable effects to the nervous system (Cheng et al., 2013; Müller et al., 2018).
In the previous research discussed, Cheng et al. (2013) examined four areas that are related to the dorsolateral prefrontal cortex and how the impact of heroin affected the different areas. The four areas included the orbitofrontal cortex, the entorhinal cortex, the occipitoparietal cortex and the anterior cingulate cortex. All of the previously stated areas in combination are responsible for emotion, cognition, memory, perception of time, decision-making, and visuospatial tasks. All of the results demonstrated that each area was negatively impacted by heroin abuse (Cheng et al., 2013). For an individual to have deficits with decision-making, memory, perception of time, visuospatial abilities, and emotion portrays how harmful heroin abuse can be in everyday life (Cheng et al., 2013). Müller et al. (2018) determined the link between heroin abuse and telomerase activity, which is responsible for aging. The results go to further justify how heroin negatively impacts the lives of people addicted to opioids. The previous articles help further the research of the specific areas that are impacted by heroin abuse and make progress for how specific areas can be further examined. Research is important in order to develop better treatment regiments and to further understand the significant impact of opioid addiction.
Due to the prevalence of opioid addiction I originally assumed that there would be a plethora of research on the topic of opioid addiction. However, I realized websites discussing opioid addiction were more accessible compared to research articles with a purpose, methods, and results. I realized that the websites I found provided information about general structures that were impacted and that the websites said that research has found significant impacts, but the research was not provided to back up the facts. While I think lay references may aid the general public in understanding difficult topics such as opioid addiction, the lay references often give vague statements that allow for misinterpretation. For someone to understand what is happening in the nervous system, further research is needed to look beyond the vague statements to understand what is happening. I found that reading lay references was less dense, but that the websites left me with many questions. Research articles are difficult to read at times due to the complexity of terms, but more information is offered with methods to explain where and how the information was retrieved and how the information is reliable. Lay references may provide people with inaccurate information, which can then distort the perception of opioid addiction.
