Assessing Presentation of Narcolepsy Worldwide

Incidence prevalence rates of narcolepsy were assessed in a meta-review of 30 countries, with a trend of underreporting found in ethnic/race and gender minorities, childhood narcolepsy type 2 (NT2), and among patients with comorbid conditions, according to study findings published in Current Sleep Medicine Reports.

Characterized by excessive daytime sleepiness with or without cataplexy, narcolepsy type 1 (NT1) and NT2 are diagnosed by clinical, electrophysiological, and biological evaluations, which often leads to a delayed diagnosis ranging from 8.7–22.1 years and risk of misdiagnosis, noted author Karen Spruyt, PhD, clinical psychologist and child psychologist at the Free University of Brussels and at the University of Chicago.

“In an era of increased sleepiness complaints at societal level; a new pandemic, coronavirus disease 2019; and personalized medicine, we aim to systematically review the literature concerning the presentation of narcolepsy in diverse populations,” wrote Spruyt.

Performing a systematic literature search in PubMed, Scopus, and Web of Science, Spruyt divided population-based data of 30 countries (209 data sets) into continents and ethnicity/race groups based on definitions set by the National Insitute of Health Diversity Programs. Spruyt categorized the study cohort by age, in which children were classified as being < 19 years and adults > 19 years.

Addressing another pandemic of the past, H1N1, Spruyt additionally sought to examine associated adverse events of rising narcolepsy incidence reported by Sweden and Finland after vaccination. She categorized data based on reports before the pandemic (< 2009), during/after (≥ 2009), and a mixture of both.

In the meta-review, there was a narcolepsy rate of 0.87–1.21 worldwide, with NT1 research noted to be prioritized in studies. Among those who were vaccinated during and after the H1N1 pandemic, the pooled incidence rate was shown to be 1.58.

“Caution is needed in interpreting these pooled rates, because the year 2009 (or H1N1 pandemic circulation) is a crude time point applied in different ways throughout the literature, particularly in combination with the recollection of the onset of symptoms of narcolepsy,” wrote Spruyt.

Spruyt additionally indicated a “striking” gap in epidemiological data involving minorities and gender disparities, with data representing mainly European and Caucasian samples.

“The reviews published since 2017 moreover highlight the gap in knowledge regarding co-occurrence of disorders that may mask symptomatology of narcolepsy,” wrote Spruyt. “Especially given the associated features of narcolepsy, such as hypnagogic or hypnopompic hallucinations, sleep paralysis, and obesity, misdiagnosis might be common.”

Reference

Spruyt K. Narcolepsy presentation in diverse populations: an update. Curr Sleep Med Rep. Published online November 25, 2020. doi:10.1007/s40675-020-00195-7