PM and DM consolidation in DLD (Earle & Ullman, 2021)

Purpose: This study examined procedural and declarative learning and consolidation abilities in adults with developmental language disorder (DLD) relative to their typical language (TD) peers.

Method: A total of 100 young adults (age 18–24 years) with (n = 21) and without (n = 79) DLD participated across two sites. Performance measures on a recognition memory task and a serial reaction time task were used to assess declarative and procedural memory, respectively. Performance was measured shortly after learning (8 a.m.) and again after a 12-hr, overnight delay (8 a.m.).

Results: Linear mixed-effects modeling was used to examine the effects of time and group membership on task performance. For the serial reaction time task, there were significant effects of group (TD > DLD) and time (Day 1 > Day 2), but no interaction between them. For the recognition memory task, there was a significant interaction between group and time, driven by overnight gains in the TD group, combined with stable performance across days by those with DLD.

Conclusions: In procedural memory, adults with DLD demonstrate a learning deficit relative to adults without DLD, but appear to have comparable retention of learned information. In declarative memory, adults with DLD demonstrate a deficit in the overnight enhancement of memory retrieval, despite typical-like learning exhibited when tested shortly after encoding.

Supplemental Material S1. Participant performance on additional instruments; relationships between experimental measures of memory and language-related functions.

Earle, F. S., & Ullman, M. T. (2021). Deficits of learning in procedural memory and consolidation in declarative memory in adults with developmental language disorder. Journal of Speech, Language, and Hearing Research. Advance online publication. https://doi.org/10.1044/2020_JSLHR-20-00292