The Natural History of Health and Symptoms in Narcolepsy: a 10 year Longitudinal Study

The aim of the study was to compare, over a 10 year period (1991/2001), reported changes in people with narcolepsy in terms of (1) life impact of symptoms (2) sleep propensity (3) body mass index, and (4) concomitant illnesses. Also, to document, using retrospective report, (5) environmental factors influencing narcolepsy severity, and (6) reported time of worst symptom severity following narcolepsy onset.\ud In 1991 127 people with diagnosed narcolepsy and cataplexy completed a wide ranging questionnaire. In 2001 attempts were made to recontact these participants and 67 were traceable. Of these, 47 people, (18 males, 29 females; mean age 61.76 years, age range 31-86 years) returned a revised questionnaire. The reported impact of excessive daytime sleepiness (EDS) on the ability to carry out day to day activities showed minor increases in severity over the 10 year period in this older narcolepsy sample, and this could not be attributed to major changes in medication status. It is argued that the underlying severity of EDS does not increase with time, but rather that the interaction of EDS with the aging process increases its detrimental impact. There was no evidence that any narcolepsy symptom became substantially worse with time for most people with the disorder. The influence of environmental factors on symptoms was inconsistent within the group. In terms of other health issues, the elevated BMI, stable over time, suggested that excess weight may be a trait often associated with narcolepsy, possibly linked to hypocretin deficiency. A high prevalence rate of diabetes was noted in the sample