Years after a heroin addiction, a completely rehabilitated 38 year old man begins to feel the urge to shoot a needle again. The feelings of immortality, the sense of being atop the world, and the illusion that anything is possible all crowd his conscience. He craves the euphoria and the days when he could escape the stress of the working world. Everything begins to remind him of those days, from the shoddy, deserted street of his local dealer to the red brick building where he used to hide his needles. His mind begins to feel impaired, his vision swirls, and his cravings deepen. He doesn’t understand why he feels this way—he was done, the drug was out of his system, he was healthy again. Weeks later, he relapses and doctors are shocked. The last time he felt like this was over 18 years ago. The withdrawal stages had passed. Was the drug not removed from his memory and his brain?
The “sleeper effect,” discovered by Yale’s Carl Hovland, is a psychological trend which first found its way into social application through World War 2. The original context of the effect is that information coming from a discredited source becomes significantly more accepted when enough time passes that a subject cannot clearly remember the origin of the source. For example, a study was conducted on two groups of students who read an article on nuclear power. One group was told the source was an American Scientist, whereas the other was told that a Soviet Newspaper was the publisher. In the short term, the two groups showed a very different attitude in regards to the article. However, a few weeks later, when the origin of the paper was not as clearly remembered, both groups showed the same attitude toward the article. The memory of the article subconsciously lingered in the brains of the subjects as an influence while the source of information was slowly forgotten. Thus, the sleeper effect is noted as being the lingering influence of a given subject that goes unnoticed in day-to-day life but still has cognitive effects on behaviors and decision making.
The sleeper effect can be altered and reapplied in the context of drug addictions. For example, even when an individual is thought to have completely overcome dependency on a drug and its effects, the memory of the drug and its influence is never completely eradicated. The same negative effects that impaired users can show up years after stopping the use of drugs because the drug will always be in the back of the persons’ mind. When people are reminded of their former addictions, environmental triggers that evoke memories seem to wake up the “sleeping” addiction. Neuronal connections are reactivated and chemicals are released in the brain, effecting cognitive changes in vision, coordination, and other processes that the drug would normally alter. Yale researchers discovered that when patients reach this stage, it is often an accurate indicator of a relapse.
With all of this in mind, the sleeper effect has great implications for alcohol, the most accessible and abused drug today. Alcohol and alcoholism are studied in depth at the Yale Center for Translational Neuroscience of Alcoholism. The center use techniques such as functional Magnetic Resonance Imaging (fMRI), Positron Emission Tomography (PET), and methods involving psychopharmacology to study alcoholism and its effects on the brain. Dr. John H. Krystal, Professor of Clinical Pharmacology and the deputy chairman for research, explains the sleeper effect in the context of alcohol.
“First, people who are most prone to alcoholism are thrill-seekers, those who want immediate satisfaction,” explains Krystal. “However, there is also a genetic predisposition, a heritability that is associated with drinking.” According to Dr. Krystal, neural circuits in our brain learn to associate different feelings with alcohol consumption. For instance, drinking relieves stress and makes the drinker more carefree and outgoing. This positive reinforcement tells the brain that to relieve stress and to feel the relaxation that is a result of becoming drunk, one must consume alcohol. Similarly, to feel high, attain euphoria, and undergo psychedelic experiences and illusions that tease the strings of the mind, drug addicts find it necessary to shoot a needle or light up a joint.
Once an addiction forms, dependence is established between the user and the substance. The longer the abuse continues, the stronger the neuronal connections become. However, at the same time, the abuser can start to develop tolerance to the effects of the substance. For example, once an alcoholic has been drinking for enough years, his or her body will not react as heavily to the same amount of alcohol. Also, the negative feedback receptor in the brain, a signal that tells someone to stop drinking, is activated much later in the drinking process. Thus, after many more drinks, one begins to feel sick and nauseous, which are some of the body’s different negative feedback mechanisms, and decides to quit for the night. Similarly, users of marijuana will become tolerant to getting “high” and will need to smoke much more of the plant to achieve the same effects.
The essence of the sleeper effect comes into play once a drug abuser has been rehabilitated from the addiction. Dr. Krystal likened the human mind to a computer options menu. When decisions are made, we subconsciously have our own drop-down menus of what action we will choose to take. The problem is, once the neuronal connections that are associated with drugs or alcohol have been created in our brain, they can never be removed. Their importance is bumped down the list—a drug which used to be the primary choice in a daily course of decisions may be pushed to the bottom and often not regarded, but it can never be forgotten. When signs and situations arise that remind people of times when they used the drug, or when the former addict feels extremely stressed or in mental states he used to experience during his period of drug abuse, the drug is shifted up the menu and becomes more appealing and desirable. The need to use the drug can be awoken by anything that triggers memories, in essence activating the neuronal circuitry associated with the drug use, and thus creating a need to return to former habits. This triggering can also artificially create cognitive effects that parallel those of the drug, such as reduced learning and memory impairment. These symptoms are fabricated in our own minds—chemicals are released that mimic the effects of the drug upon the recollection of its memory. This can occur months after quitting or years afterward. People can never fully stop thinking about the drug because it is out of their control whether an environmental factor stimulates the receptors in their brains. “People are vulnerable to becoming conditioned to withdrawal-like effects, even years after an addiction has passed,” explains Dr. Krystal. We can almost call it a mental reflex, something that is immediate and uncontrollable. In essence, what we perceive and what goes on in our minds is often out of our control. A way to erase the memories of drugs and their associated mental states has yet to be discovered —our minds have recorded and stored our experiences, and the best we can do is push them down our daily lists. Ultimately, neuronal connections that are established can never be destroyed completely. An addiction can be put to sleep but never truly forgotten.