Ryno Kruger and Dr. J. Dee Higley, Psychology Department
In 2014, 8.7 million teenagers in the United States reported drinking alcohol, with the vast majority engaging in binge drinking1. Due to the rise of underage drinking and alcohol abuse, it is of increasing importance to study variables that influence risk for alcohol abuse and alcoholism. To study these factors, I spent 10 weeks at the California National Primate Research facility (CNPRC).
Though alcohol consumption in human adolescents is studied via self-report surveys, there are a myriad of difficulties with self-report methodologies, including under-reporting and other inaccuracies. A nonhuman primate model is a useful means of addressing this concern. Rhesus monkeys possess a number of similarities to humans, including sharing about 97% of their genes. Further, rhesus monkeys will readily consume alcohol, with about 10-20% drinking to intoxication on a daily basis, a pattern similarly seen in humans.
The purpose of this study was to test a new method of assessing intrinsic tolerance to ethanol in adolescents in a nonhuman primate model, providing an alternative to administering alcohol. Alcohol and ketamine (a widely-used sedative in laboratory and pediatric settings) have been shown to be cross-tolerant2, and pilot data from Dr. Higley’s lab and others have shown a correlation exists between tolerance towards ketamine and inherent alcohol sensitivity.
Five alcohol-naïve adolescent rhesus monkeys were selected from a population of about 4,000 monkeys. Subjects met criteria for exhibiting high and low temperamental anxiety. Prior to alcohol-exposure, subjects were administered ketamine on four separate occasions. I recorded subjects’ recovery time from ketamine exposure on each of these occasions. Subjects were then given access to aspartame-sweetened water for one hour a day over a one-week training period. Then, subjects were given access to an aspartame-sweetened alcohol solution for two hours a day over an eight-week experimental period.
Preliminary analyses suggested a positive correlation between sensitivity to ketamine and sensitivity to alcohol.
The results seem promising in providing an alternate method for assessing sensitivity to alcohol. With a positive correlation, the use of Ketamine in predicting alcohol sensitivity is useful in determining early signs of possible future alcohol abuse or alcoholism. This positive correlation could change alcohol research to expand its boundaries due to not having to administer alcohol and thus enlarging the study population. By knowing whether an adolescent is sensitive to alcohol or not can inform parents or authorities to institute preventative measures early in life. These preventative measures can aid in halting the increase of underage drinking, and even reduce the number of individuals participating in this behavior.
Our next step will be to increase our sample size by testing a future cohort using this same methodology. By increasing the sample size, we hope to see a bigger effect size and validate our preliminary findings in a replicable way. This research is important and needs to be pursued.
- Substance Abuse and Mental Health Services Administration (SAMHSA) (2014). Behavioral health trends in the United States: Results from the 2014 National Survey on Drug Use and Health, 19-21. Retrieved from http://www.samhsa.gov/data/sites/default/files/NSDUH-FRR1-2014/NSDUH-FRR1-2014.pdf
- Dickerson, D., Pittman, B., Ralevski, E., Perrino, D., Limoncelli, D., Edgecombe, J., G. Acampora, G., Krystal, J.H., & I. Petrakis, I. (2008). Ethanol-like effects of thiopental and ketamine in healthy humans. Journal of Psychopharmacology, 24, 203-2011