Narcolepsy-Associated Genes Influence Sleep Quality in Older Adults

Sleep characteristics are significantly associated with certain narcolepsy genetic markers, according to the results of a study published in the journal Sleep Science and Practice.

Many patients with narcolepsy type 1 (NT1) report frequent night awakenings (30% to 95%). However, night time sleep disturbance in NT1 patients is under researched.

To investigate the relationship between genetics of narcolepsy and sleep, researchers from the Manchester University NHS Foundation Trust in the United Kingdom sourced data from the University of Manchester Longitudinal Study of Cognition in Normal Healthy Old Age (UMLCHA). Healthy adults (N=6063) were recruited for the UMLCHA between 1982 and 1994 (median age, 65.19 years; women, 69.9%). Sleep quality was assessed at 5 timepoints using the Personal Details Questionnaire (PDQ) and outcomes were related with 13 non-major histocompatibility complex (MHC) single nucleotide polymorphisms (SNPs) associated with narcolepsy.

At baseline, 12.1% of participants reported using sleep medication and 24.9% rated their current health status as very good.

In the first sleep assessment, participants reported obtaining an average of 6.97 hours of sleep a night, had a sleep efficiency of 81.45% and woke up 1.35 times per night. Difficult sleep was reported by 35.63%. Over time, fewer individuals reported having difficulty sleeping, but sleep efficiency declined.

The SNP rs4290173 was significantly associated with the time individuals reported going to bed (b, -0.098; P =.028) and midpoint sleep (b, -0.083; P =.021), while rs1154155 was associated with sleeping through the night (odds ratio [OR], 1.242; P =.043) at baseline.

Using longitudinal changes in sleep outcomes, the change in wake episodes was associated with:

• rs2834168 (b, 0.232; P =.005),
• rs2859998 (b, 0.173; P =.042),
• rs1551570 (b, -0.194; P =.018), and
• rs10915020 (b, -0.345; P =.024).

The change in napping hours was associated with rs306336 (b, 1.023; P =.035); and the change in wake up time associated with rs10995245 (b, 0.144; P =.012).

This study was limited by relying on self-reported data and by the participant attrition over time, in which the sample size in the 5^th sleep assessment was 575.

“While not all narcolepsy sufferers will experience these conditions, the support of a genetic screening assay may help guide clinicians when diagnosing the primary condition,” the researchers concluded.