Contemporary Neuroscience and Addiction
Dr. Tim Koeltzow, left, with psychology major Brent Baker. Koeltzow began his neuroscience studies in the 1990s. Although he is interested in all areas of psychology, his primary focus is on the biological basis of behavior and mental processes.
In the 1970s, the same decade President Richard Nixon declared a “War on Drugs,” cocaine, a powerfully addictive stimulant, gained widespread popularity and was considered the champagne of illegal drugs. By the mid-1980s and the early 1990s, crack cocaine use became rampant, especially in major U.S. cities. “Crack cocaine is delivered immediately to the brain, leaving people feeling as if they want and need more,” said Dr. Tim Koeltzow, associate professor of psychology at Bradley.
Ten years ago, Koeltzow began investigating the increased vulnerability to substance abuse for adolescents with ADHD. There may be three distinct reasons why ADHD might be linked to substance abuse: (1) individuals with ADHD may take drugs to self-medicate the symptoms; (2) the drug treatment may paradoxically promote drug craving; and (3) the impulsive nature of those with ADHD may simply lead them to make bad decisions in terms of drug usage.
To address the second possibility, Koeltzow utilized a rat model with certain features of ADHD and delivered equal doses of the drug Ritalin either continuously or multiple times a day. His research indicated that taking the drug multiple times a day promoted subsequent cocaine-seeking. “If the drug was given continuously, the dopamine levels were only modestly elevated but enough to block irrelevant events from demands on attention. It appears that dopamine synapses adapt to the continuous presence of Ritalin, which actually leads to a diminished sensitivity to cocaine. This finding means that individuals taking sustained-release medications should actually be at reduced risk of addiction.”
Stress is also a factor that promotes substance abuse and relapse though Koeltzow notes there may be an important distinction between good stress and bad stress: “Initially, something may prove stressful, but just as we gather strength in subsequent physical workout sessions, so can we become impervious to subsequent stressors.”
To assess the impact of stress on drug taking and subsequent drug usage, Koeltzow studied rats reared in an enriched environment versus those reared in a standard cage. Environmental richness may include novel objects, tunnels and running wheels. He found the response to cocaine for those reared in an enriched environment was attenuated, and they were less likely to be addicted to cocaine versus those housed alone. This situation may ultimately provide insight into the mechanisms by which some people show resilience to stress or protection from addiction.
Individual responses to threat, according to Koeltzow, are a function of environmental variability times the interaction of genetics and environment. Understanding how genes and environment interact to promote addiction is a key focus of contemporary neuroscience.
Koeltzow cautions against the idea that enrichment is always good or will be the main focus of future treatment. “What we are finding in the lab is that if rats are exposed to the novelty of an enriched environment for the first time when they are also exposed to cocaine, we see an increase in the long-term sensitivity to cocaine,” he said. “Clearly, the effect of drugs has something to do with the context in which drugs are taken. We need to further study how novelty and the environment interact with drug actions, particularly in the prefrontal cortex.”
Koeltzow is representative of Bradley’s faculty in his student-centered focus in building strong foundational skills. “The primary objective of my lab is to encourage students to solve problems or do something that no one has ever done before,” he said. “That work might be designing, analyzing, or interpreting a new experiment and then presenting at a national conference or publishing a paper.”
Koeltzow’s hope for his students is to serve humankind and, ultimately, all organisms to the best of their ability. “One day, I hope that just as we can test insulin levels to detect diabetes, we have biological diagnostics that measure the physiological parameters indicative of mental health.”
By Susan Andrews
Photography by Duane Zehr