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mental effects if heroin
December 6, 2018

How Heroin Affects Behavior

Heroin is an illicit synthetic opiate chemically derived from morphine. The Schedule 1 drug is outlawed in every form in the US, but is sometimes prescribed abroad to treat severe pain after more conservative options have been exhausted. In the past two decades, heroin’s popularity exploded—undergoing a radical transformation from moderately used street-drug to ubiquitous killer. According to the Centers for Disease Control and Prevention (CDC), heroin use tripled between 2003 and 2014, with heroin-related deaths experiencing a five-fold increase since 2000. 

Heroin is feared by public health authorities and despised by law enforcement agencies for the culture of death and crime it produces. Although heroin overdoes are an increasingly common reason for emergency room (ER) visits and extended hospital stays, the long-term behavioral impact of the drug on users is even more disturbing.


Heroin addiction is associated with a broad spectrum of behavioral dysfunction. Once heroin use becomes the priority in a person’s life and hijacks rational thought processes, unfavorable changes inevitably follow. People caught in the grips of heroin addiction often prioritize the drug at the expense of important relationships and commitments—personally and professionally. In many cases, heroin addiction follows a predictable pattern that begins with discreet, occasional use and quickly progresses to obvious behavioral symptoms including:

  • Theft of money or valuables
  • The visible presence of drug paraphernalia
  • Lying, elusiveness and withdrawal
  • Obvious personality changes
  • Use of heroin slang and drug culture terms

Heroin is a powerful, debilitating narcotic capable of dramatically impacting mood. Like other opiates, heroin effectively rewires a user’s brain by making it dependent on the “feel good” chemicals it unleashes in the brain’s pleasure and reward center. The primary neurochemical mechanism involved in this process is the neurotransmitters dopamine and serotonin—both of which are known for inducing euphoric states. By artificially flooding the brain with addictive chemicals, heroin almost always creates a backlash. Smitten by the intoxicating pleasures of the drug, users require more frequent use and higher doses to duplicate the initial high. And so begins a vicious, extremely destructive cycle.     

Many heroin users suffer from a debilitating battery of personal, professional and legal consequences as a result of their addiction, even in its early stages. School performance, career or job productivity, and social and romantic relationships all suffer from the onslaught of negative changes triggered by the deadly narcotic. The impaired judgment, impulsivity and diminished cognitive function associated with heroin use create a climate of instability and irresponsibility that has long-lasting, and sometimes permanent, consequences—not only for heroin addicts, but also for family and friends. Whatever short-term benefits are gained by the expensive, highly unpredictable opiate, are overshadowed by the disastrous effects.  

Heroin systematically destroys young, still-developing minds prior to full cognitive development, derails successful careers, alienates families, and sabotages the health and happiness of those dependent on its intense, fleeting high. It’s irrational influence on behavior and judgment-clouding side-effects are overwhelming. For example, heroin is frequently smuggled into prisons where it is abused by those already convicted of drug-related offenses, or used as an escape mechanism by those already suffering from trauma, chronic physical pain or co-occurring mental health disorders such as anxiety and depression.


Heroin’s terrible behavioral impact is frequently the result of damage and/or structural changes to the following brain regions, structures and functions:

  • The prefrontal cortex (PFC)—described by brain scientists as the “human supercomputer,” this delicate, complex brain region is responsible for a number of key cognitive functions including planning, reasoning, decision-making, judgment and impulse-control. These abilities, also known as “executive functions,” are vital to healthy adult functioning and significantly damaged by chronic heroin use.   
  • The medial temporal lobe—one of the first structures to be damaged by chronic heroin use, the medial temporal lobe is responsible for auditory perception and the conscious memory of facts and /or events. A heroin-damaged medial temporal lobe results in accelerated aging and significant cognitive impairments. In some cases, the medial temporal lobe of a heroin-damaged individual resembles that of a much older person.
  • The hippocampus—a delicate brain region usually impacted by accidents and hard falls—the hippocampus regulates critical aspects of learning and memory. Once damaged, a number of professional, academic and autonomous functions are significantly impacted.
  • White and gray matter—the human brain and central nervous (CNS) are comprised of a complex network of neurons, axons, receptors, clefts and hormonal systems. Although sturdy and capable of self-regeneration to a certain extent, it was not designed to endure a constant bombardment of potent opiates. Mounting empirical evidence implicates heroin in the disruption and death of both white and gray matter—key components of healthy cognitive function. White matter is often referred to as the “subway of the brain,” responsible for connecting different regions and allowing smoothly transmitted electrical signals, while gray matter helps control sight, hearing, muscle movement, speech and emotion. The progressive deterioration and destruction of both associated with heroin addiction is devastating.

It is difficult, if not impossible, to determine exactly how long the behavioral impact of heroin lasts; however, neuroscientific research has conclusively proven that brain dysfunction associated with heroin addiction is long-lasting. In multiple randomized, controlled studies, subjects suffered from cognitive deficits and other symptoms of brain damage for a period of at least three years following abstinence. In effect, this means that abnormal behaviors and negative personality changes persist well beyond the timeframe involved in active heroin addiction. In cases involving excessive and prolonged exposure spanning years, the damage may be permanent. Regardless of the severity of damage and number of years lost to active addiction, professional, medically managed detox and rehabilitation treatment are essential for preserving cognitive function and optimizing long-term recovery outcomes.  

For more about heroin addiction and recovery, check out these related articles:


Journal of the American Chemical Society. Development of a Clinically Viable Heroin Vaccine. June, 2017.

The Lancet. Feasibility, safety, and efficacy of injectable heroin prescription for refractory opioid addicts: a follow-up study. October, 2001.

International Journal of Drug Policy. Exposure to fentanyl-contaminated heroin and overdose risk among illicit opioid users in Rhode Island: A mixed methods study.  August, 2017.

Frontiers in Neuroscience. Abstinent Heroin Addicts Tend to Take Risks: ERP and Source Localization.  Dec, 2017.