Might Accurate Heartbeat Perception Increase the Risk for Alcoholism?
Many individuals cope with anxiety by consuming alcohol. Because alcohol effectively reduces tension, the drinking is reinforced and, with time, alcoholism can result. In fact, adults with a panic disorder are about three times more likely than others to develop an alcohol use disorder. Still, much uncertainty exists about how alcohol dampens anxiety. A previously unexplored possibility is that, for some, alcohol impairs interoceptive sensitivity – the ability to accurately perceive one’s internal sensations.
To get a better sense of what is meant by interoception, try now to sense your heartbeat. The pressure of blood surging through your vessels. Motility within your gastrointestinal tract.
Individuals who are more accurate at such tasks are at higher risk for trait anxiety as well as for certain anxiety disorders, including panic disorder. Those with this condition, for example, often catastrophically appraise normal bodily sensations. So, an elevated heart rate might be misinterpreted as reflecting an imminent heart attack. In short, greater interoceptive sensitivity may increase the risk for panic attacks by amplifying the base of somatic sensations that have the potential to be viewed as threatening.
The present study aimed to provide a proof-of-concept test of the hypothesis that alcohol impairs interoceptive sensitivity.
How was this study conducted?
Sixty-one social drinkers came to the lab in small groups on two days spaced a week apart. Each participant was randomly assigned to receive vodka sours targeting a blood alcohol content of .05% on one testing day and placebo drinks on the other, with the order counter-balanced. On both testing days, participants engaged in a heartbeat perception task on three occasions: at baseline, after consuming alcohol, and after physiological arousal was raised via exercise. For these tasks, participants were asked to silently count the number of heartbeats they detected between two tones, while the actual number of heartbeats was recorded.
What were the main findings?
The primary findings were that, for men only, alcohol impaired interoceptive accuracy relative to a placebo both while quietly standing (low arousal condition) and following exercise (high arousal condition). These findings are partially consistent with past studies in which moderate doses of alcohol compromised other forms of perception, such as depth perception and proprioception, in both men and women. Providing a possible – though untested – mechanism for the present findings, alcohol is known to affect the “interoceptive cortex,” which includes the dorsal posterior insular, anterior insular, prefrontal, and cingulate cortices, and ventromedial thalamus.
Our finding of a sex difference in interoception builds on past literature; for example, men on average have greater interoceptive sensitivity. This sex difference has yet to be explained satisfactorily, though hypotheses ranging from differences in cardiac volume, body fat distribution, and motivation have been suggested. Additionally, men are more likely to self-medicate clinical anxiety symptoms with alcohol than are women.
What are the next steps?
The present study employed healthy, social drinkers. Future studies should directly examine whether, among individuals with anxiety disorders, interoceptive sensitivity mediates the relation between alcohol consumption and state anxiety. Should evidence for this emerge, specific treatments for co-morbid alcoholism and clinical anxiety among individuals high in interceptive sensitivity could be tested.
For example, biofeedback could serve as a healthier alternative to drinking and allow anxious individuals to observe inaccuracies in their perceptions of somatic symptoms and gain a sense of control over certain cardiovascular processes. Additionally, though beta-blockers, which block beta-adrenergic receptors and hence prevent cardiovascular arousal, have a mixed track record in the general treatment of panic, they could specifically assist co-morbid patients high in interoceptive sensitivity.
These findings are described in the article entitled The effects of alcohol on heartbeat perception: Implications for anxiety, recently published in the journal Addictive Behaviors. This work was conducted by Kenneth Abrams, Kate Cieslowski, Stacey Johnson, Sam Krimmel, Gabby Bierlein-De La Rosa, Kirstie Barton, and Pombie Silverman from Carleton College.