Narcolepsy an Independent Cardiovascular Disease Risk Factor

HOUSTON — Narcolepsy is associated with a significantly increased risk for cardiovascular disease (CVD) and major adverse cardiac events (MACEs), independent of common comorbid conditions and medications commonly used to treat the chronic sleep disorder, according to two new studies.

A nationwide analysis revealed that people with narcolepsy had a 77% higher risk for CVD and an 82% higher risk for MACE than those without the disorder.

“These findings indicate that it is important for clinicians to regularly monitor patients for cardiovascular disease and take this into consideration when recommending specific treatments for narcolepsy,” study investigators Christopher Kaufmann, PhD; Munaza Riaz, PharmD, MPhil; and Rakesh Bhattacharjee, MD, told Medscape Medical News.

“Additionally, physicians should consider monitoring the presence of other health conditions as contributing factors to the risk of CVD,” they said. Kaufmann and Riaz are with the University of Florida, Gainesville, Florida, and Bhattacharjee is with the University of California San Diego.

They presented their research on June 3 at SLEEP 2024: 38th Annual Meeting of the Associated Professional Sleep Societies.

Independent Risk Factor

The National Institute of Neurological Disorders and Stroke reports an estimated 125,000 to 200,000 people in the United States live with narcolepsy. The condition often coexists with other common health conditions including obstructive sleep apnea (OSA), diabetes, and other comorbidities, which can all contribute to the risk for CVD.

This raises doubt as to whether narcolepsy itself directly leads to CVD or if it is the result of these comorbid health conditions. Additionally, some medications used to treat narcolepsy carry their own cardiovascular risks.

Using the IBM MarketScan Commercial and Medicare supplemental databases, the researchers identified 34,562 adults with a diagnosis of narcolepsy and a propensity-matched comparison cohort of 100,405 adults without narcolepsy. The patients had a mean age of 40 years, and 62% were women.

Compared with adults without narcolepsy, those with the chronic sleep disorder that causes overwhelming daytime drowsiness had a 77% increased risk for any CVD (hazard ratio [HR], 1.77) and an 82% increased risk for MACE (HR, 1.82).

They also had an increased risk for stroke (HR, 2.04), heart failure or myocardial infarction (MI; HR, 1.64), and atrial fibrillation (HR, 1.58).

The results were similar in a separate analysis of the same population that also controlled for baseline use of stimulants, oxybates, and wake-promoting agents — medications commonly used to treat excessive daytime sleepiness associated with narcolepsy.

In this analysis, narcolepsy was associated with an 89% higher risk for CVD (HR, 1.89) and a 95% increased risk for MACE (HR, 1.95). The risk for any stroke (HR, 2.06), heart failure (HR, 1.90), atrial fibrillation (HR, 1.66), and MI (HR, 1.93) was also higher in those with narcolepsy.

“Our study found that even after considering the presence of health conditions like obstructive sleep apnea, diabetes, hypertension, hyperlipidemia, and even depression, as well as medication use, there still appears to be an independent relationship between narcolepsy and CVD,” the investigators said.

They cautioned that the mechanisms explaining the link between CVD and narcolepsy are unclear and warrant further study.

“Sleep fragmentation is a hallmark of narcolepsy, and it is speculated that this fragmentation, which may trigger disturbances in autonomic function, predisposes individuals to CVD. In rodent models, a possible link has been observed between hypocretin — a central neurotransmitter that is reduced or deficient in patients with narcolepsy — and atherosclerosis.

“However, it remains uncertain whether this is the primary mechanism related to CVD,” they commented.

Compelling Evidence for Higher CVD

Commenting on the findings for Medscape Medical News, Shaheen Lakhan, MD, a neurologist and researcher based in Miami, Florida, called for narcolepsy to be recognized as a significant contributor to higher CVD risk.

“Given the compelling evidence linking narcolepsy to a higher incidence of cardiovascular disease, it is crucial that narcolepsy be included in clinical guidelines and risk assessment tools alongside other known risk factors,” said Lakhan, who was not involved in this research.

“Physicians and healthcare providers should proactively address the increased cardiovascular risk associated with narcolepsy by incorporating preventive strategies and interventions into the management of patients with this condition,” Lakhan suggested.

Regular CVD screening, a healthier lifestyle, and targeted therapies could all decrease cardiac risk, Lakhan added.

“Ultimately, novel disease-modifying therapies for narcolepsy should target the core mechanisms driving the increased cardiovascular risk associated with this condition. By elucidating the specific biological pathways and developing targeted therapies that address the unique challenges faced by narcolepsy patients, we can effectively mitigate the risk,” Lakhan said.

The studies were funded by the Sleep Research Society Foundation. The authors and Lakhan had no relevant disclosures.