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Cognitive Impairment

The complex puzzle of addiction

By Jennifer T. Allen

ALCOHOL IS THE MOST COMMONLY USED ADDICTIVE SUBSTANCE IN THE UNITED STATES, according to the National Council on Alcoholism and Drug Dependence. One in every 12 adults, 17.6 million people, suffer from alcohol abuse or dependence. Several million more engage in risky, binge drinking patterns that could lead to alcohol problems. Looking into the reasons individuals become addicted to alcohol is why Dr. Mark Fillmore came to the University of Kentucky from Canada 17 years ago.
“UK was actively recruiting individuals for substance abuse research in various departments,” said Fillmore, professor in the Department of Psychology. “Psychology was one of them, and I was eager to come to the United States and Kentucky because there was a lot of interest in drug abuse research here.”
Fillmore’s research is a combination of psychology, behavioral neuroscience, biology and pharmacology. Looking at the differing ways individuals react to drugs of abuse, whether the drug be alcohol, marijuana, or some other drug of abuse, may give insight into why some people become dependent on a drug over time.
“The reason we are interested in the individual difference in how people react is because it gives us clues as to why some individuals get addicted to a drug and other individuals do not,” Fillmore said. “The problem with drug abuse is that while many individuals are exposed to drugs, like alcohol, only a few develop an addiction to it, and we need to understand why these individuals develop addiction.”
Utilizing state-of-the-art eye tracking technology, Fillmore and the graduate and undergraduate students working in his lab are able to track how much time individuals look at alcohol or drug-related images or ads. There are two devices: the first is a monitor that the subject looks at while it tracks eye movements as various images rotate on the screen; the second is a mobile device the subject wears to track eye movements while looking and walking around a room.
“One of the phenomena we have noted in addiction is that addicts or individuals who are developing substance abuse problems have a heightened attention or attraction to the visual cues for the drug. They look at liquor ads in a magazine longer; they look at a billboard that shows a brand of alcohol; or they look at a bar as they are driving down the road,” Fillmore explained.
As the subjects walk around a room, the technology tracks their eye movements and records the time spent looking at objects. “This measure is called the fixation time and individuals who have a greater risk for developing alcohol abuse will look at and be drawn to these visual cues more than someone who is a moderate drinker,” Fillmore said.
Fillmore’s lab also utilizes an advanced driving simulator that can be programmed with a myriad of driving scenarios to challenge motor skills such as information popping up on the windshield or having to make a decision between two different options. The simulator takes many factors into account such as the ability to stay in your lane and not weave, the ability to maintain a safe distance from other vehicles, and the ability to maintain a certain speed.
So, what has been learned in almost two decades of research?
Fillmore’s lab has been interested in how a drug can affect someone’s ability to react quickly to a situation or to suppress a reaction. Alcohol is commonly believed to disinhibit behavior or make an individual more impulsive. The laboratory models examine the degree to which a dose of alcohol can impair someone’s ability to inhibit an inappropriate action.
Fillmore has found that under alcohol, individuals are impaired in the ability to suppress actions.
“What is interesting is that the impairment also predicts several aspects of the individual’s behavior with respect to alcohol,”

While many individuals are exposed to drugs like alcohol, only a few develop an addiction to it, and we need to understand why these individuals develop addiction.

- Mark Fillmore

Professor in the Department of Psychology


Fillmore said. “Individuals who have greater difficulty inhibiting a reaction under alcohol tend to drink more when we give them an opportunity to consume alcohol in the lab. They are also more drawn to alcohol-related images.”
The lab also looks at how alcohol can affect generalized impulsivity in other aspects, such as drinking and driving. “We are now learning how alcohol does not just impair driving skills—we’ve known that for decades. Now we are seeing how alcohol can increase an individual’s proclivity to take risks behind the wheel,” Fillmore explained.
Looking at DUI offenders and people with repeated DUI offenses, Fillmore has found that these individuals do not report feeling the effects of alcohol as strongly as others and begin to display greater risk-taking when in a driving simulation situation under an acute dose of alcohol.
One of the major impacts of this research has been to identify impulsivity and impulse control as an important factor in developing addiction.
“For years prior to this work and similar work of my colleagues, the notion of addiction was that it was reward driven, that individuals take drugs simply because they feel good,” Fillmore said. “What we have shown is that outside of the realm of reward, these individuals also have impaired inhibitory control under the drug, which actually impairs their ability to stop ongoing behavior such as taking the next drink.”
As Fillmore and his team look to the future, they are taking their work on drug-induced disinhibition into the realm of social situations, beyond studying individuals in isolation. “We know that drug abuse is a social problem, and drugs, particularly among young adults, are used in social settings,” Fillmore said. “We also know from neuroimaging studies that individuals like drugs more when they take them in a group setting when among friends.”



Nick Van Dyke, a 5th year doctoral student in Mark Fillmore's lab, demonstrates new eye tracking technology.


Fillmore’s next step includes studying how drugs may produce greater disinhibition and greater cognitive impairments when individuals are taking them in the context of parties and peer groups. He also plans to look at how individuals on social networks begin to use drugs and how their traits influence their peers.
“We are recognizing that a major contributor to drug abuse is peer influence, particularly among young adults,” Fillmore said. “We are asking: Do particular types of traits, such as disinhibition and poor impulse control, get passed along and more expressed under drugs in group settings?”
As Fillmore’s lab embarks on the next set of questions, they continue to move closer to solving the complex puzzle of addiction.

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