Daily activity performance in congenital and childhood forms of myotonic dystrophy type 1: a population-based study

To identify and describe the profile characterizing motor and process skills during daily activity performance in individuals with congenital and childhood forms of myotonic dystrophy type 1 (DM1) and to investigate differences in performance between subgroups.

Sixty participants (34 males, 26 females, mean age=17y 8mo, SD=6y 0mo, range 5y 8mo-29y 0mo) were divided into severe congenital (n=9), mild congenital (n=20), and childhood (n=31) DM1 subgroups. Daily activity performance was evaluated using a standardized observational instrument: the Assessment of Motor and Process Skills.

Deficits in performance were more pronounced in process than motor skills. Performance more than 2 SDs below age-specific norms was seen in 65% of participants for process skills and 33% of participants for motor skills. The cut-off scores indicated a potential need for assistance in daily activities for 79% of participants older than 18 years of age (n=28) due to deficient process skills.

Extensive deficits in daily activity performance were found in congenital and childhood forms of DM1, mainly owing to deficient process skills. Such skills impact on the ability to perform daily activities and could explain dependency in individuals with DM1. Process skills should be considered when evaluating daily activity performance.

Young people with myotonic dystrophy type 1 show deficits in motor and process skills when performing daily activities, compared with normative data. Deficits in process skills were more pronounced than deficits in motor skills.