DENVER – Young to early middle-aged men with insomnia symptoms are at increased risk for cardiovascular and cerebrovascular events, according to an analysis from the landmark CARDIA study.
“We found that younger to mid-life men with difficulty initiating sleep or with more than one insomnia symptom were at greater risk for incident cardiovascular disease events. And despite the fact that women in general seemed to be more prone to report those sleep difficulties, those that did were not at increased risk,” Megan E. Petrov, PhD, reported at the annual meeting of the Associated Professional Sleep Societies.
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It is well established that insomnia in older adults is associated with increased cardiovascular risk. For example, a meta-analysis of 13 prospective studies with more than 123,000 subjects concluded that insomnia was associated with a 45% increased risk of fatal and nonfatal cardiovascular events (Eur J Prev Cardiol. 2014 Jan;21[1]:57-64). But those studies typically involved older individuals, which makes cause and effect more difficult to determine because so many chronic conditions become more prevalent with advancing age, noted Dr. Petrov of Arizona State University in Phoenix.
“We wanted to see if insomnia is truly an early risk factor in the pathogenesis of cardiovascular disease and stroke,” she said.
To do so, she and her coinvestigators turned to the CARDIA database. CARDIA (the Coronary Artery Risk Development in Young Adults study), is a National Heart, Lung, and Blood Institute–sponsored prospective, epidemiologic study.
She reported on 2,950 non-Hispanic black or white participants aged 33-45 and free of any history of cardiovascular disease in 2000-2001, when they answered questions about insomnia symptoms. Difficulty in initiating sleep was reported by 16.3% of men and 20.7% of women. Difficulty maintaining sleep was a problem for 9.3% of men and 14.5% of women. And 20.6% of men and 20.1% of women reported frequent early morning awakening.
During a mean 11.5 years of prospective follow-up, 4.1% of men and 2.3% of women had a fatal or nonfatal MI, stroke, transient ischemic attack, heart failure, peripheral vascular disease, or hospitalization for an acute coronary syndrome.
In a multivariate logistic regression analysis fully adjusted for demographics, socioeconomic status, body mass index, blood pressure, diabetes, depression, health behaviors, medications, thyroid disease, and kidney problems, men who reported difficulty in getting to sleep had a 2.64-fold increased risk of one of these adverse outcomes. That was the only insomnia symptom associated with significantly increased risk. However, men but not women who reported having more than one insomnia symptom had a 39% increased risk of a cardiovascular event for each additional symptom.
Prior studies have shown that insomnia is associated with cardiac sympathetic hyperactivation. That observation suggests a plausible mechanism for increased cardiovascular and cerebrovascular risk, but it doesn’t explain why that risk was confined to young men in CARDIA. One possibility is that because of gender-related differences in perception, men tend to report having insomnia symptoms only when the insomnia is more severe, Dr. Petrov suggested.
The strengths of the CARDIA study are that all cardiovascular endpoints had to be physician certified, and the study includes a large black population. A study limitation is the relatively small number of cardiovascular events, as to be expected in a younger population. Thus, confirmation of the new findings in another large data set will be important, she noted.
As a next step in her research, Dr. Petrov said she plans to drill down in the CARDIA data to see if race modified the impact of insomnia symptoms on cardiovascular outcomes. Black participants reported all insomnia symptoms more frequently than did whites. For example, difficulty initiating sleep was reported by 25.7% of blacks, compared with just 13.5% of whites, and early morning awakening was twice as prevalent among the black participants.
Also, CARDIA participants provided self-reported sleep duration data. It will be illuminating to see if sleep duration had a modifying effect upon the insomnia/cardiovascular risk association observed in men, she said.
Dr. Petrov reported having no relevant financial conflicts.