Substance use disorder is common in those with bipolar disorder at a rate of seven times higher than in the general population. Alcohol is the most commonly abused substance in those with bipolar disorder at a rate of 25-30%. Those with alcohol dependence tend to have a worse course of bipolar disorder. Because of this, it’s important to understand why people with bipolar disorder experience alcohol dependence at a higher rate than others. A new study looks at the link between alcohol dependence and bipolar disorder at a neurological level in order to find the potential for different treatment options.

The current study, led by J J Prisciandaro of the Medical University of South Carolina in Charleston, SC, looked at 78 individuals with bipolar disorder and alcohol dependence, 19 with bipolar disorder alone, 20 people with alcohol dependence alone and 19 healthy controls. The goal was to research active levels of two communication chemicals in the frontal lobe of the brain- prefrontal gamma-aminobutyric acid (GABA) and glutamate- in each of the participants and observe any differences in levels between the groups.

Glutamate and GABA are both amino acids that act as neurotransmitters throughout the nervous system. GABA and glutamate work in a balance to speed up and slow down different brain functions. They’re important in memory, learning and social behaviors.

It has been shown that pharmaceuticals that increase GABA tend to have relaxing, anti-anxiety effects. Alcohol can also increase levels of GABA, but levels decrease dramatically as blood-alcohol levels decrease. Combining alcohol and mood stabilizers, which often impact GABA, can cause dizziness, problems concentrating, motor control issues and depression.

Participants in the current study were given a baseline evaluation including ratings of depression and mania, alcohol testing and drug testing. Following the evaluations, patients were given a magnetic resonance spectroscopy (1H-MRS), a specialized version of an MRI, to measure levels of GABA and glutamate in brain tissue.

The researchers found that levels of GABA and glutamate were significantly lower in people who were in the bipolar disorder/alcohol dependent group, especially in those who had been drinking in the two weeks prior to testing. Those with only bipolar disorder or only alcohol dependence did not show any difference when compared to the healthy controls, although previous research has shown increased levels of glutamate in people with bipolar disorder.

Decreased levels of GABA and glutamate have been associated with impulsivity and craving, making treatment more difficult in those with both bipolar disorder and alcohol dependence. Impulsivity in bipolar disorder is associated with many risky behaviors including excessive spending and sex along with increased drug and alcohol use. Increasing cravings obviously puts someone with alcohol dependence at risk of increased consumption.

The results of this study may help researchers identify ways to help this particularly high-risk group. Perhaps medications that increase GABA and glutamate activity in this part of the brain may provide a new direction for treatment. More research is necessary to find the answer.

 

 

 

 

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Image credit: Leo Hidalgo