Alcohol, substance misuse causes brain changes, reducing ‘cognitive flexibility’

Substance misuse affects ‘cognitive flexibility’

People have the capacity to adapt their thinking to change their behavior. A term for this is cognitive flexibilityTrusted Source.

As noted by the authors of this study, cognitive flexibility allows people to adapt their actions based on their environments to achieve favorable outcomes.

N​on-study author Ben Spielberg, a neuroscientist, and CEO of Bespoke Treatment, explained more about the importance of cognitive flexibility to Medical News Today:

“Cognitive flexibility is a complex phenomenon that typically refers to the ability to shift one’s mental focus and adapt to new obstacles, goals, and patterns. Being able to think and act effectively in response to changes in stimuli, environments, and surprises signifies a healthy level of cognitive flexibility. Cognitive flexibility is important because our environment is rapidly changing, and when our thinking patterns remain rigid and fixed, we become unable to adapt to our environment.”

Authors of the current study note that the use of certain drugs and alcohol has been linked to reduced cognitive flexibility.

Study author Dr. Jun Wang with the Texas A&M University School of Medicine stated that this study aimed “to explore why addictive substance use reduces cognitive flexibility.”

How cocaine and alcohol affect cognition

T​his study utilized mice and rats to look at the influence of cocaine and alcohol on cognitive flexibility and then look at the underlying mechanisms involved.

To test cognitive flexibility, researchers used reversal learning tasks. This involves tasks where the outcomes and actions are reversed from what they were before.

Among rats and mice exposed to cocaine, they found impairments in cognitive flexibility.

Looking at the brain pathways affected by cocaine, they found that cocaine aids in inhibiting specific neurons called striatal cholinergic interneurons (CINs).

Researchers knew from previous data that continued exposure to addictive substances makes the activity of direct-pathway medium spiny neurons (dMSNs) more potent. They found that cocaine exposure appeared to strengthen inhibitory signals from direct-pathway medium spiny neurons (dMSNs) to striatal cholinergic interneurons (CINs). Their research further supports that alcohol has a similar influence.

Study authors also found that cocaine exposure decreased CINs firing to an area of the brain called the dorsomedial striatum (DMS). This area of the brain is critical for cognitive flexibility.

The data provides insight into some of the potential mechanisms behind why addictive substances inhibit cognitive flexibility. The discovery of these mechanisms may be useful in developing therapeutics to treat substance use disorders.

Dr. Wang explained a little more about the neural pathways the team studied to MNT:

“The mechanisms underlying reinforcement-induced reduction of cognitive flexibility is not clear. This research found that dMSN activation by substance use reduces CIN function, reducing flexibility via a collateral projection from dMSNs to CINs. In another word, dMSN-to-midbrain mediates reinforcement, whereas dMSN-to-CIN reduces cognitive flexibility.”

Spielberg noted that while substance misuse “is linked to impulsivity at initial stages (e.g., before physiological dependence kicks in), the brain switches to a compulsive pattern once one becomes dependent on the drug.”

“In this study, we see how some of that switch between impulsivity and compulsivity takes place — neurons are sending signals to release high levels of dopamine, which then inhibits other deep structures that enforce cognitive flexibility. As this cycle of behavioral abuse continues, the structures continue to inhibit cognitive flexibility, thus leading to a negative feedback loop,” Spielberg added.

More research on the impact of substance use on the human brain needed

The main limitation of this study is that researchers conducted the study in rodents, which can not immediately translate to work with humans.

Further research is needed to understand how alcohol and cocaine influence pathways in the human brain. For example, it is unclear what levels of alcohol or cocaine intake impair cognitive flexibility. Dr. Wang explained to MNT:

“This paper reveals an innate circuit that mediates reinforcement-induced cognitive flexibility. But we have not explored at what levels of alcohol or cocaine use will reduce cognitive flexibility. It is generally believed that alcohol or cocaine use disorder, which is defined as compulsive alcohol or cocaine use despite negative sequence, will induce [persistent] changes at dMSN-to-CIN transmission and thus reduce CIN function and consequently cognitive flexibility.”

T​his study adds to growing evidence on the impact of addictive substances.

People living with addiction or substance misuse can seek help from several resources to curb the potentially detrimental effects of addiction.

Addiction treatment can involve long-term management and learning new behaviors that challenge old habits.

People seeking help with addictions can also benefit from therapy that helps them change their thinking and actions.

Spielberg explained some of the aspects of addiction recovery to MNT:

“Once someone has medically detoxicated from substances, the current standard of care involves a community-based treatment program such as a Partial Hospitalization Program (PHP) or Intensive Outpatient Program (IOP). It’s important to note that many people with substance abuse disorder also suffer from an additional underlying mental health diagnosis, which must be addressed in treatment. These diagnoses are typically a combination of PTSD, depression, anxiety, OCD, ADHD, and bipolar disorder.”