Cocaine, alcohol abuse linked to brain changes, cognitive decline

New York, July 8 Researchers have found that addiction to cocaine or alcohol use disorders can lead to long lasting changes in the brain and also cause cognitive decline. 

The study led by a team from the Texas A&M University School of Medicine showed that these substances of abuse can detrimentally affect people's cognitive flexibility -- the ability to adapt and switch between different tasks or strategies.

Although previous research has hinted at this connection, the underlying reasons for this cognitive impairment remain elusive.

Cognitive flexibility is a crucial element in various domains of our life, including academic achievement, employment success and transitioning into adulthood.

As we age, this flexibility plays an important role in mitigating cognitive decline.

A deficiency in cognitive flexibility, however, is linked to academic deficits and a lower quality of life.

The research, published in the journal of Nature Communications, emphasises the role of the local inhibitory brain circuit in mediating the negative effects of substance use on cognitive flexibility.

Substance use influences a specific group of neurons called striatal direct-pathway medium spiny neurons (dMSNs), with projections to a part of the brain known as the substantia nigra pars reticulata (SNr).

Conversely, cognitive flexibility is facilitated by striatal cholinergic interneurons (CINs), which receive potent inhibitory signals from the striatum.

"Our hypothesis was that increased dMSN activity from substance use inhibits CINs, leading to a reduction in cognitive flexibility," said Jun Wang, associate professor in the Department of Neuroscience and Experimental Therapeutics at the varsity.

"Our research confirms that substance use induces long-lasting changes in the inhibitory communication between dMSNs and CINs, consequently dampening cognitive flexibility. Furthermore, the dMSN-to-SNr brain circuit reinforces drug and alcohol use, while the associated collateral dMSN-to-CIN pathway hinders cognitive flexibility," Wang added.

The study provides new insights into the brain circuitry involved in the impairment of cognitive flexibility due to substance use, the researchers said.