Modafinil Reduces Parasympathetic Activity but Does Not Influence Autonomic Reactivity to Orthostatic Load in Narcolepsy Type 1.

INTRODUCTION

Modafinil may affect autonomic functions in healthy subjects. The aim of the study was to assess the long-term modafinil administration influence on the cardiac autonomic reactivity to orthostatic load in patients with narcolepsy type 1.

METHODS

In 15 patients (4 male; 11 female; median age, 47 years; range, 18-70 years) with narcolepsy type 1 treated with modafinil in daily dose of 100 to 300 mg, the short-term spectral analysis of heart rate variability (HRV) in supine-standing-supine test was performed before and after 72 hours of modafinil discontinuation.

RESULTS

The sympathovagal reactivity to orthostatic load was not modified by modafinil treatment; nevertheless, the parasympathetic activity expressed by length of R-R interval and high-frequency component of HRV is reduced in supine position in patients taking modafinil.

CONCLUSIONS

We conclude that long-term use of modafinil does not influence the cardiac autonomic reactivity to orthostatic load expressed by the HRV changes in supine-standing-supine test in narcolepsy type 1 patients, but the parasympathetic cardiac activity may be reduced in quiet supine position in patients with narcolepsy taking modafinil.