Science has come a long way in helping us understand the way the brain changes in addiction. In this section, we will provide updates of current research on addiction, recovery, and the brain.
First, a few key points to understand about the brain and addiction.
Some characteristics of addiction are similar to other chronic diseases.
Just as cardiovascular disease damages the heart and changes its functioning, addiction changes the brain and impairs the way it works. Below is an image of the brain (left) and the heart (right).
These images show how scientists can use imaging technology to measure functioning of the brain and heart. Greater activity is shown in reds and yellows, and reduced activity is shown in blues and purples. Both the healthy brain and the healthy heart show greater activity than the diseased brain and heart, because both addiction and heart disease cause changes in function. In drug addiction, the frontal cortex in particular shows less activity. This is the part of the brain associated with judgment and decision-making (NIDA).
Addiction is similar to other chronic diseases in the following ways:
- It is preventable
- It is treatable
- It changes biology
- If untreated, it can last a lifetime
Drugs of misuse trick the brains reward system.
The brain can experience pleasure from all sorts of things we like to do in life; eat a piece of cake, have a sexual encounter, play a video game. The way the brain signals pleasure is through the release of a neurotransmitter (a chemical messenger) called dopamine into the nucleus accumbens, the brains pleasure center. This is generally a good thing; it ensures that people will seek out things needed for survival. But, drugs of misuse such as nicotine, alcohol, and heroin also cause the release of dopamine in the nucleus accumbens, and in some cases, these drugs cause much more dopamine release than natural, non-drug rewards.
Below is a picture (helpguide.org) of the brain and the nucleus accumbens, in addition to some other brain regions that are affected by addition.
And, here is a picture from our own research of the brain activated by alcohol (Gilman et al., 2008). The nucleus accumbens is activated.
Addictive drugs can provide a shortcut to the brains reward system by flooding the nucleus accumbens with dopamine. And, addictive drugs can release two to 10 times the amount of dopamine that natural rewards do, and they do it more quickly and more reliably (helpguide.org).
Over time, drugs become less rewarding, and craving for the drug takes over. The brain adapts to the effects of the drug (an effect known as tolerance), and because of these brain adaptations, dopamine has less impact. People who develop an addiction find that the drug no longer gives them as much pleasure as it used to, and that they have to take greater amounts of the drug more frequently to feel high. There is a distinction between liking and wanting the drug; in time, the liking decreases and the wanting increases. Over time, people use the drug simply to feel normal. They continue to seek and take drugs despite the tremendous problems caused for themselves and their loved ones.
The Brain Can Recover- but it Takes Time!!
How the brain recovers from addiction is an exciting and emerging area of research. There is evidence that the brain does recover; in the image below shows the healthy brain on the left, and the brain of a patient who misused methamphetamine in the center and the right. In the center, after one month of abstinence, the brain looks quite different than the healthy brain; however, after 14 months of abstinence, the dopamine transporter levels (DAT) in the reward region of the brain (an indicator of dopamine system function) return to nearly normal (Volkow et al., 2001).
There is limited research on the brains recovery from alcohol and marijuana use. However, recent studies have shown that some recovery does take place. For example, one study found that adolescents that became abstinent from alcohol had significant recovery with respect to behavioral disinhibition and negative emotionality (Hicks et al., 2012). Lisdahl and colleagues posit that this could mean that some recovery is occurring in the prefrontal cortex after a period of abstinence. Furthermore, other research has found that number of days abstinent from alcohol was associated with improved executive functioning, larger cerebellar volumes and short-term memory. While promising, this field of research is in its infancy and there have been conflicting results that instead show minimal to no recovery from cognitive deficits. This is especially true for studies evaluating the brains recovery from marijuana use, specifically IQ. On the other hand, some studies have shown that former marijuana users demonstrate increased activation in parts of the brain associated with executive control and attention. Whether this is associated with the compensatory response or brain recovery has yet to be determined.
What is clear is that alcohol and marijuana do have neurotoxic effects and, to some degree, this damage can be reversed. There is minimal evidence on how we can improve brain recovery from substance use, but emerging literature suggests that exercise as an intervention may improve brain recovery. Physical activity has been shown to improve brain health and neuroplasticity. In previous studies of adults, physical activity has improved executive control, cerebral blood flow and white matter integrity. While none of these interventions have been done in adolescent alcohol or marijuana users, this approach is promising and should be investigated further.