Evaluation of Periodic Limb Movements in Sleep and Iron Status in Children With Autism

Abstract

Objective: Recent data suggest that both disordered sleep and low serum iron occur more frequently in children with autism compared with children with typical development. Iron deficiency has been linked to specific sleep disorders. The goal of the current study was to evaluate periodic limb movements in sleep and iron status in a group of children with autism compared with typically developing children and children with nonautism developmental delay to determine if iron status correlated with polysomnographic measures of latency and continuity and periodic limb movements in sleep.

Methods: A total of 102 children (68 with autism, 18 typically developing, 16 with developmental delay) aged 2 to 7 years underwent a one-night modified polysomnography study and phlebotomy at the National Institutes of Health to measure serum markers of iron status (ferritin, iron, transferrin, percent transferrin saturation).

Results: No serum iron marker was associated with periodic limb movements of sleep or any other sleep parameter; this did not differ among the diagnostic groups. No significant differences among groups were observed on serum iron markers or most polysomnogram parameters: periodic limb movements in sleep, periodic limb movements index, wake after sleep onset, or sleep efficiency. Children in the autism group had significantly less total sleep time. Serum ferritin was uniformly low across groups.

Conclusions: This study found no evidence that serum ferritin is associated with polysomnogram measures of latency or sleep continuity or that young children with autism are at increased risk for higher periodic limb movements index compared with typically developing and developmental delay peers.

Trial registration: ClinicalTrials.gov NCT00298246 NCT00409747.

Keywords: autism; ferritin; iron; periodic limb movements.

Conflict of interest statement

Disclosures: Ms. Lane, Dr. Buckley, Dr. Farmer, Dr. Thurm, and Dr. Swedo make no disclosures. Dr. Rodriguez reports no conflicts of interest and has served as a paid speaker for Intermezzo and Nuvigil in the past 24 months. Dr. Felt reports no conflicts of interest and has served as a consultant for Pfizer in the past 12 months.

Published by Elsevier Inc.

Figures

Figure 1

No significant Pearson correlations observed between serum iron markers and PSG parameters Note: PLMS=total period leg movements of sleep; PLM Index=periodic leg movement index; WASO=wake after sleep onset. Additional iron markers available for a subset of the sample, n=60 (65% of AUT, 56% of TD, 38% of DD). All Pearson correlations ≤ .25 and p>.01.