Leg movements during sleep in children treated with serotonergic antidepressants

Study Objectives: To evaluate leg movements during sleep (LMS) in children taking serotonergic antidepressants, compared to those of children with restless legs syndrome (RLS) and controls, and to assess the time structure of intermovement intervals (IMI). Methods: Twenty-three children (12 girls, mean age 14.1 years) on antidepressants and with a total LMS index ≥ 15/h, 21 drug-naïve RLS children (11 girls, mean age 13.6 years) also with total LMS index ≥ 15/h, and 35 control children (17 girls, mean age 14.3 years) were recruited. LMS were scored and a series of parameters was calculated, along with the analysis of their time structure. Results: Children taking antidepressants showed higher total and periodic LMS (PLMS) indexes than both controls and RLS children, as well as higher short-interval and isolated LMS indexes than controls. LMS periodicity was highest in children on antidepressants. In children taking antidepressants, a well-defined PLMS IMI peak corresponding to approximately 10-60 s, with a maximum at approximately 20 s was present, which was much less evident in RLS patients and absent in controls. A progressive decrease of PLMS during the night and more frequent arousals were found in children on antidepressants and with RLS. Conclusions: Children taking serotonergic antidepressants show higher periodicity LMS than children with RLS or controls and have a higher number of PLMS through the night. Antidepressant-associated PLMS in children seem to have features similar to PLMS of adults with RLS. Whether this is a marker of an increased risk to develop RLS later in life needs to be determined. Statement of Significance The findings of this study show that serotonergic antidepressant use in children is associated with periodic leg movements during sleep (PLMS) with features similar to the typical PLMS of adults with restless legs syndrome (RLS). This is in contrast to PLMS of children with RLS, in whom the adult pattern starts developing during adolescence. Also, based on genetic findings reported in the earlier literature, we hypothesize that the antidepressant accelerated "maturation"of PLMS might indicate an increased susceptibility to develop RLS symptoms later in life. However, additional studies are needed with long-term prospective data to fully understand the clinical meaning of PLMS associated with antidepressant use.