Age at onset of narcolepsy in two large populations of patients in France and Quebec, 2001, Dauvilliers et al.

[ScoutB]

Age at onset of narcolepsy in two large populations of patients in France and Quebec
Authors: Y Dauvilliers, J Montplaisir, N Molinari, B Carlander, B Ondze, A Besset, M Billiard

Abstract​

Background
Narcolepsy usually starts around adolescence; however, there is great variability in the clinical presentation of narcolepsy.

Objective
To determine the age at onset in conjunction with severity of narcoleptic symptoms in two large populations of narcoleptic patients with a similar genetic background.

Methods
Information on age at onset and severity of the condition was obtained in 317 patients with well-defined narcolepsy-cataplexy from Montpellier (France) and in 202 from Montreal (Canada).

Results
The mean age at onset was 23.4 years in Montpellier and 24.4 in Montreal. The age at onset was bimodal in two independent patient populations: a first peak occurring at 14.7 years, and a second peak occurring at 35. Age at onset clearly differentiates patients with a positive family history of narcolepsy (early onset) from those without a family history. Other clinical and polygraphic findings may indicate that young age at onset is associated with increased severity of the condition (higher frequency of cataplexy and decreased mean sleep latency on the Multiple Sleep Latency Test).

Conclusion
Bimodal distribution of age at onset of narcolepsy was found in two independent patient populations. Our data suggest that age at onset is genetically determined.

(Note this study is from 2001)
Web | DOI | Sci-hub | Neurology | Paywalled

 

[ScoutB]

After reading a couple of recent threads on narcolepsy (eg. @jnmaciuch's here), I was curious about the age distribution of onset and found this study (which I don't think has been posted before?).

It's intriguing that they found a dual peak situation similar to what others have suggested exists in ME/CFS. I've only skimmed the paper so far and don't know much about this kind of epidemiology, so am curious what others think. @Jonathan Edwards I know you've been interested in both an ME/CFS-narcolepsy connection, and the age of onset data so I'd be interested in what you make of this.

 

[ScoutB]

Here are their graphs. There seem to be 2 peaks for men as well (at least for the Canadian men).

 

[Jonathan Edwards]

Age at onset clearly differentiates patients with a positive family history of narcolepsy (early onset) from those without a family history.

I do wish someone would do a WGS analysis of early onset (<13y 0r <15y) ME/CCFS.

 

[Jonathan Edwards]

After reading a couple of recent threads on narcolepsy (eg. @jnmaciuch's here), I was curious about the age distribution of onset and found this study (which I don't think has been posted before?).

Nice find.

 

[Jonathan Edwards]

When narcolepsy was fund to be associated with HLA-DQ (as ME/CFS probably is, but in an obscure and much more limited way) we settled in to the idea that it was an autoimmune disease like a lot of others - tick box, job done.

But two age peaks throws up major questions about how that would fit. And the autoimmune story always seemed a bit atypical and incomplete for narcolepsy.

I can't help thinking all this is telling us something important.

 

[SNT Gatchaman]

I can't help thinking all this is telling us something important.

Just a thought, but

A persistent whiff of cholesterol.

Global lipid metabolism must be changing in association with newly active steroid hormones in adolescence. Is it going through an onset and offset phase as things ramp up, peak in early adulthood and then presumably ramp down afterwards? Could those two "ramp" periods be vulnerable?

 

[Sean]

I can't help thinking all this is telling us something important.

I increasingly get the feeling that in general there are now sufficient clues sitting there in front of us, but we don't have the right conceptual framework yet to make the connections and draw a good research map.