The importance of GABA for persistent intrusive thoughts

Persistent intrusive thoughts are a hallmark symptom of several psychiatric disorders like anxiety, depression, PTSD, and schizophrenia. Those who suffer from these disorders are often unable to "turn off" persistent memories, worries, and sometimes even hallucinations. This has been frequently attributed to a "deficient inhibitory control by the prefrontal cortex," but a recent study suggests a strong relation to the neurotransmitter GABA in the hippocampus (Schmitz et. al, 2017).

The prefrontal cortex is responsible for functions such as planning, reasoning, problem solving, memory, and personality, so it makes sense it would be involved in many psychiatric problems. Thus much research for treatment of these disorders has been focused on the prefrontal cortex. But in Schmitz et. al's study published earlier this month, they found that these persistent intrusive thoughts are associated with increased hippocampus activity. As you may be aware, the hippocampus is responsible for memory storage and emotional responses. GABA is commonly referred to the brain's main "inhibitor," as it suppresses signal transmissions between neurons. These researchers proposed that the inability to turn off these intrusive thoughts is due to hippocampus hyperactivity from dysfunctional GABAergic interneurons.

Researchers triggered reminders of unwanted thoughts and then analyzed fMRI images of participants. What they found was that when there were higher levels of GABA in hippocampus, there was stronger control over the fronto-hippocampal inhibitory pathway. In other words, those with higher concentrations of GABA in their hippocampus were better at blocking intrusive thoughts and memories. Interestingly, this control over the inhibitory ("blocking") pathway was not found to be correlated with GABA in the prefrontal cortex.

These findings indicate that the inhibition of persistent negative thoughts is related to the GABAergic inhibition of hippocampal retrieval processes. Such information is critical in creating new approaches to treatment, as previously most of the focus has been on improving prefrontal cortex functioning.



SOURCES:

Schmitz, T. W., Correia, M. M., Ferreira, C. S., Prescot, A. P., & Anderson, M. C. (2017). Hippocampal GABA enables inhibitory control over unwanted thoughts. Nature Communications, 8(1). doi:10.1038/s41467-017-00956-z

Scientists find key to unwanted thoughts. (2017, November 03). Retrieved November 25, 2017, from http://www.bbc.com/news/health-41847030