46. Abnormal sympathetic and cardiovascular reactivity during mental stress in patients with narcolepsy and cataplexy

Abstract

To ascertain abnormalities of sympathetic and cardiovascular reactivity during mental stress in patients with narcolepsy and cataplexy (NC). We studied 10 untreated patients with established criteria for NC and hypocretin deficiency, and 15 sex and age matched healthy subjects. Subjects underwent sitting microneurographic recording of muscle sympathetic activity (MSNA) from peroneal nerve, heart rate (HR) and blood pressure (BP) during resting state and mental stress (3-min of paced auditory serial arithmetic test -PASAT) and a cold test (two minutes immersion of a hand in ice water). The awake state was continuously monitored by an ambulatory polygraphic recorder. NC patients disclosed a tendency to show decreased MSNA and BP during resting state compared to controls although the difference was not significant. However during mental stress NC patients showed decreased MSNA, BP and HR compared to controls but no difference were found during cold test. Our data demonstrated a decreased sympathetic and cardiovascular reactivity during mental stress in NC patients suggesting a possible effect of hypocretin on autonomic reaction during mental activation as reported in animal models.