A biomarker is a physical or biological difference in a particular group that identifies them from other groups . For example, researchers have identified specific biomarkers that can indicate an increased vulnerability of certain women to develop breast cancer.
A biomarker does not necessarily indicate that the person will develop a particular disorder, just that the person is at a higher risk to develop the disorder in question. Biomarkers are extremely hard to identify for psychiatric problems such as depression, bipolar disorder, addictions, and very few have been identified even though there is quite a bit of research that attempt to locate them .
However, if reliable biomarkers could be identified for disorders such as addiction these would be extremely useful in identifying people who are more vulnerable to developing a specific type of addiction and then implementing early forms of intervention. A recent study investigated the potential for specific brain biomarkers to identify an increased likelihood of addiction to stimulants .
Using Brain Scans to Predict Addiction Vulnerability
The researchers looked at two samples of occasional users of amphetamine-type stimulants to determine if any particular differences in the brain volume of the individuals would be associated with the transition from occasional use to more chronic, addictive-type usage. The participants in the study underwent structural brain imaging and then were monitored after 12 and 24 months to assess their level of drug use. The researchers found that individuals who went from occasional use to more chronic addictive type use displayed smaller volumes in the brain areas associated with decision-making at the beginning of the study, particularly in the areas of the prefrontal cortex and the amygdala . These areas of the brain are involved in such things as decision-making, the ability to control one's actions, monitoring fear or anxiety, and memory .
The researchers hypothesized that the findings suggest that smaller brain volumes in these particular regions may be associated with greater impulsivity and poor decision-making. This might make an individual more susceptible to transitioning from occasional amphetamine use to more chronic or addictive usage.
Challenges of the Study
However, even though this particular study found the relationship between brain volume and later behavior, there are a number of issues here. First, the research is correlational research and therefore it cannot demonstrate that having smaller brain volume is in these particular areas causes one to develop an addiction.
Secondly, the sample in this study could not be used to generalize people outside of the study. Far more research with different and more participants would is needed.
Moreover, the findings suggest that such things as a tendency towards impulsivity may be related to later chronic drug use. Thus, behavioral measures of impulsivity would be better predictors of later proneness to addiction than brain scans would be and these also would be quite a bit less expensive.
Finally, these types of studies are notorious for their inability to replicate. Quite a bit of follow-up research is needed to indicate the reliability of these findings.
 Hatfield, R. C. (2013). The everything guide to the human brain. Avon: MA: Adams.
 Becker, B., Wagner, D., Koester, P., Tittgemeyer, M., Mercer-Chalmers-Bender, K., Hurlemann, R., ... & Daumann, J. (2015). Smaller amygdala and medial prefrontal cortex predict escalating stimulant use. Brain, awv113.
Dr. Hatfield is a clinical neuropsychologist with extensive experience assessing and treating neurological and psychiatric disorders. His areas of expertise include neurobiology, behavior, dementia, head injury, addiction, abnormal psychology, personality disorders, statistics, rehabilitation psychology and research methodology.