RESUMO
BACKGROUND: The aim was to gain a UK national sample of people with Rett syndrome across the age range and (1) conduct a cross-sectional comparison of age groups and (2) undertake a longitudinal follow-up. METHODS: From 308 potential participants approached to take part, a sample of 91 girls and women was achieved (29.5%). Their ages ranged from 4 to 47 years, and 71 were known to have a mutation in the methyl-CpG binding protein-2 (MECP2) gene. Seventy-two of the initial sample were followed up 16 months later, and 50 returned completed assessments (69.4%). Their ages ranged from 7 to 48 years, and 42 were MECP2 positive. Parental questionnaire measures of Rett syndrome specific characteristics, impulsivity, overactivity, mood, interest and pleasure, repetitive behaviour and self-injury were administered. RESULTS: Adaptive behaviour and behavioural characteristics of Rett syndrome were similar across age groups and, where assessed, stable over time, as were repetitive behaviours generally and self-injury. There was some suggestion of deterioration in health arising with ageing, principally contributed to by deteriorations in dental and gastro-intestinal problems both with moderate effect sizes. Indicators of mood, interest and pleasure differed significantly across age groups. The total scale score significantly deteriorated over time, with a moderate effect size. CONCLUSIONS: This study provides further evidence for the post-regression stability that characterises Rett syndrome. Emergent low mood in Rett syndrome requires further research.