Cardiac dysautonomia and serotonin plasma levels in Rett syndrome

BACKGROUND: In Rett syndrome the autonomic nervous system is abnormal at various levels, from the central to the peripheral nervous system. A role for serotoninergic dysfunction has been suggested. OBJECTIVES: The aim of our study was to evaluate the relation between cardiac dysautonomia (expressed by means of heart rate variability) and plasma serotonin levels in girls affected with Rett syndrome. Heart rate variability and plasma serotonin levels were evaluated in 28 Rett girls aged 1-14 years. A Pearson correlation was used to determine whether there was a relationship between plasma serotonin levels and each heart rate variability parameter. RESULTS: In untreated Rett girls the plasma serotonin levels correlated with the sympathovagal balance, as expressed by the low frequency (LF) to high frequency (HF) ratio (p<0.05). CONCLUSIONS: Our results suggest that cardiac dysautonomia could be linked to serotoninergic dysfunction and that treatment with a serotonin analogue could be useful in improving the sympathovagal balance.