Alcohol, Cognitive Function, and Atrial Fibrillation

Although alcohol has been with us for over 6000 years, we are still learning more about its good and bad effects. Moderate alcohol intake may reduce cardiovascular events, but heavy drinking can have adverse cardiac effects.

A recent study in the Canadian Medical Association Journal analyzed data on more than 30,000 individuals who had participated in 2 large antihypertensive drug trials.¹ All patients in this study were aged 55 years or older and had a history of cardiovascular disease or diabetes with end-organ damage. None had atrial fibrillation (AF) at baseline.

At baseline, 62% of participants had low levels of alcohol intake; 37% were moderate drinkers; and fewer than 2% consumed high levels. Binge drinking-defined as more than 5 drinks a day-was found in 4%: more men than women engaged in bingeing (5% versus 1%, respectively).

The main outcome was the incidence of AF. After 56 months of follow-up, 2093 had incident AF. The hazard ratio for all-cause mortality was 0.79 for moderate drinkers and 0.84 for the high-consumption group relative to the low-consumption group.

In this study, moderate to high alcohol intake was associated with an increased incidence of AF. Alcohol use was associated with a graded increase in risk of AF. The age and sex-standardized incidence rates per 1000 person-years among low-, moderate-, and high-level alcohol drinkers were 14.5, 17.3, and 20.8, respectively.

Some caveats: alcohol intake was self-reported at baseline but was not assessed during the long follow-up period. The number of binge drinkers was small (some may have dropped out of the study before it was completed). Also, the incidence of AF may have been underestimated: ECGs were not required at each follow-up visit and therefore episodes of asymptomatic paroxysmal AF may have gone undetected. 

Another important new finding was reported in the journal Heart. Ball and coworkers² found that mild cognitive impairment is highly prevalent in older high-risk patients hospitalized with AF and that it may result in more disability and morbidity than the AF itself. 

AF may also be associated with the development of vascular dementia, related to the concordant relationship with AF and its associated cardiovascular disease risk factors (including diabetes, aging, and metabolic defects associated with aging).

In short, AF can do a great deal of damage. This is a reality that those who regularly drink more than moderately need to be made aware of.  

References
1. Liang Y, Mente A, Yusuf S, et al; ONTARGET and TRANSCEND Investigators. Alcohol consumption and the risk of incident atrial fibrillation among people with cardiovascular disease.CMAJ. 2012 Nov 6. doi:10.1503/cmaj.120412
2. Ball J, Carrington MJ, Stewart S; SAFETY investigators. Mild cognitive impairment in high-risk patients with chronic atrial fibrillation: a forgotten component of clinical management? Heart. doi:10.1136/heartjnl-2012-303182