How Do Drugs Hijack Your Brain?

Smaller gray matter volumes are linked to likelihood of certain drug addictions.

Posted May 18, 2015

Wikimedia Commons/Public Domain
Source: Wikimedia Commons/Public Domain

Over the years, I’ve witnessed a handful of close friends destroy their lives because of an addiction to drugs. Of all the various drugs my peers have used, heroin and crystal meth (methamphetamine) seem to have the uncanny ability to get inside someone’s brain and hijack their pragmatic decision-making ability.

Has the free will of someone you know ever been hijacked by a drug to the point that it destroyed his or her life? Does an addiction to a substance currently dictate your life and cause you to be impulsive and make reckless or self-destructive decisions? 

Amphetamine-type stimulants are the number two most widely used illicit substance in the world and have become a significant public health problem.

I’ve often wondered why some drugs, like crystal meth, have such a strong effect on certain people and not others. I’ve never tried crystal meth, but have spoken at length with friends who've become addicts and asked them to describe what it feels like when the drug takes control of their brain. Often, they will describe the feeling of "jonesing" or craving the drug as if they're possessed and the drug has literally taken hold of their free will and drives them to risk everything to stay high for as long as possible.

How do amphetamine-like drugs, such as crystal meth, rewire the brain in a way that hijacks a person's decision-making ability, increases impulsivity, and drives certain users to risk everything in their life just for another fix and to get high again?  

Neuroscientists in Germany may have the answers. Recently, researchers from the University of Bonn identified why some of us are particularly vulnerable to becoming addicted to amphetamines. The cause may be linked to structural changes that occur in the amygdala, striatum, and prefrontal cortex which are also known as the “fronto-striato-limbic” brain regions during recreational use of these drugs. 

The May 2015 study, "Smaller Amygdala and Medial Prefrontal Cortex Predict Escalating Stimulant Use,” was published online in Brain: A Journal of Neurology.

Wikimedia Commons/Public Domain
Source: Wikimedia Commons/Public Domain

Some People Are More Vulnerable to Having Their Brain Hijacked by Drugs

The German researchers found that occasional users of amphetamines who went on to increase their drug use and become addicts showed brain structural differences after they started using the drugs. People who didn't increase their drug use also didn't show these changes in brain structure. 

The drug literally appeared to target the regions of the brain responsible for executive function, restraining impulsivity, and decision-making and caused them to atrophy. It's as if the drug systematically hijacked the person's brain and programmed an auto-pilot setting of a target behavior to seek another drug fix like a heat-seeking missile. 

For this study, the German researchers, led by Dr. Benjamin Becker, scanned the brain structure of 66 participants who occastionally used drugs in an attempt to provide the first evidence showing how volumes of fronto-striato-limbic regions of the brain changed over a two year period. 

In two separate experiments, they scanned the brain structures of all 66 participants and then measured the volumes of fronto-striato-limbic regions. These brain areas directly affect decision-making and impulsivity.

The participants of the study were all of comparable socio-economics, neurocognitive performance, and previous history of drug experimentation. After taking a brain scan, the researchers monitored the participants after 12 months and then again after 24 months to see whether their drug use had declined, stayed the same, or increased.

When the researchers compared the brain scans of all the occasional drug users, they specifically found reduced “fronto-striato-limbic” brain volume in all the individuals who had started as occasional users but went on to increase their drug intake and became addicts over the two-year period.

Those who became addicts seemed to have a built-in vulnerablility that allowed the drug to shrink specific gray matter volumes, while those who were able to use the drugs in moderation—or decreased their drug use over time—were immune to these changes in brain structure. 

Conclusion: Changes in Fronto-Striato-Limbic Brain Volume Allow Amphetamines to Hijack Decision-Making in Some Users

The findings of this research indicate that smaller brain volumes in fronto-striato-limbic regions are linked to impulsivity and decision-making that can hijack a person’s brain and make him or her vulnerable to becoming addicted to amphetamine-type stimulants.

Hopefully, reading this blog post will give anyone who has never tried these drugs a "healthy fear" about the potential power of amphetamines to hijack your brain. If your brain is vulnerable to structural changes in gray matter volume, odds are that recreational use will lead do addiction. Although this study doesn't examine opioid or heroin use, these drugs may hijack the brain in a similar way. 

In order for more effective early interventions of addiction, the researchers believe it’s essential to label more specific biomarkers that can be used to identify people who are more vulnerable to drug addiction. In a press release, Benjamin Becker said, "prospective longitudinal studies in occasional users are of great importance to determine biological vulnerability markers, which can help to identify individuals at greatest risk of developing an addiction."

Becker concluded, "these findings indicate that individual differences in fronto-striato-limbic regions implicated in impulsivity and decision making could render individuals vulnerable for the transition from occasional to escalating stimulant use."

If you'd like to read more on this topic, check out my Psychology Today blog posts:

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