Polysubstance Abuse Tied to Significant Decline in Mental Function
Substance Abuse and Mental Function
All commonly abused, mind-altering substances in the U.S. and throughout the world produce their primary drug effect in a part of the brain called the pleasure center. When present in significant amounts in the pleasure center, these substances produce varying degrees of a highly pleasurable sensation called euphoria. Physical substance dependence and substance addiction are typically the end result of the changes that repeated substance exposure produces in the output of the brain’s main pleasure-generating chemical, dopamine.
Unfortunately, a repeated pattern of substance abuse triggers much wider changes in brain function. Chief among these changes is a decline in higher-level mental skills, such as the ability to learn and accurately make and retrieve memories, the ability to think logically or solve problems, the ability to exert behavioral self-control and the ability to focus and maintain attention. Doctors and researchers commonly refer to these skills as cognitive skills. Each abused substance has its particular classic impact on the brain’s basic cognitive skill set. Some of these negative effects fade over time when substance abuse ceases; however, some of the cognitive deficits associated with substance abuse may linger for years or appear in permanent form.
Polysubstance abuse can involve any combination of alcohol, illegal/illicit drugs or mind-altering prescription medications. The main recognized danger of this form of substance use is a significantly increased risk for exposure to seriously negative related outcomes such as drug overdoses, severe alteration of normal cardiovascular (heart and blood vessel) function and mental/emotional problems such as bouts of extreme anxiety and episodes of psychosis (hallucinations and/or delusions) that resemble the psychotic effects of schizophrenia and similar mental health conditions. Some people intentionally engage in polysubstance abuse; however, many affected individuals unknowingly engage in the practice when they consume drugs that contain an undisclosed combination of two or more substances.
Impact on Cognitive Function
In the study published in The American Journal on Addictions, researchers from the University of Florida, Johns Hopkins University, Columbia University and the Moffitt Cancer Center used an examination of 552 polysubstance abusers to gain a more detailed perspective on how this type of substance abuse affects basic cognitive function. All of the study participants were primarily users of cocaine and heroin; specific forms of intake for these drugs included inhalation of heroin, smoking of “crack” cocaine and injection of cocaine, heroin or a “speedball” containing both cocaine and heroin. Additional substances consumed by at least some of the individuals in the study included alcohol, marijuana and cigarettes/nicotine. In addition to assessing substance use, the researchers gathered basic education and age data for each person.
The researchers identified five distinct groups of polysubstance abusers among the study participants: “older nasal heroin/crack smokers,” “older, less educated polysubstance users,” “younger multi-substance injectors,” “less educated heroin injectors” and “more educated heroin injectors.” The members of each of these groups also consumed some combination of alcohol, marijuana and cigarettes/nicotine. The researchers concluded that all five groups of polysubstance abusers had cognitive skills that were noticeably diminished when compared to the rest of the adult population. They also concluded that, for the most part, older polysubstance abusers and relatively poorly educated polysubstance abusers had larger cognitive deficits than their younger and relatively better educated counterparts. The notable exception to this rule was “more educated heroin injectors;” these individuals experienced a greater decline in their cognitive skills than “younger multi-substance injectors.”
The study’s authors believe their work adds substantially to the evidence-based understanding of how specific combinations of polysubstance abuse affect the brain’s cognitive skill set. They also believe that their work provides future researchers with an effective example of how to clarify the complex picture of the connections between polysubstance abuse and the subsequent decline in mental abilities.