Memory
Discrepant findings were observed across studies that investigated
memory performance in children with SDB. These results were observed
across a range of memory measures, such as the Children’s Memory
Scale,20-21,37 California Verbal Learning
Test,21,38 and NEPSY32 memory
tasks.17,19,39-40 Children with SDB performed in the
average range on working memory tasks.17,20 On verbal
memory tasks, multiple studies indicated average
encoding,17,21 consolidation,17,21short-term retrieval, 17,21 long-term
retrieval,21 and recognition
abilities17,21 across list
learning21 and story learning tasks.17,21 Multiple studies suggested similarly average
encoding, consolidation, short-term retrieval, and long-term retrieval
abilities on visual memory tasks.17,20 Despite broadly
average performance, some studies that included a control group reported
differences in memory abilities for children with and without
SDB.19,39-40 These differences were observed across
verbal memory tasks,19 visual memory
tasks,19 and tasks with both verbal and visual
components.39-40 Kheirandish-Gozal et
al39 measured non-verbal memory with four learning
trials, an immediate recall trial, and a delayed recall trial and
reported that children with SDB had lower overall performance on the
first trial and over all four total trials compared to children without
SDB. In addition, children with SDB had lower performance on the
immediate and delayed recall trials compared to children without
SDB.39 These results indicate that children with SDB
may have difficulties with the acquisition and retention of new
information. A more recent study supported these findings by reporting
that children with OSA had poorer overall memory consolidation than
controls on a spatial declarative memory task.40
Limited research has investigated differences of SDB severity level on
memory performance. One study of SDB in school-aged children reported
slight differences according to SDB severity; children who had mild SDB
performed higher than children with moderate SDB on a narrative memory
measure.16 Another study of SDB in overweight
adolescents reported no differences among individuals with primary
snoring, mild, or moderate SDB on verbal memory.21
To determine the impact of SDB on memory, multiple studies investigated
associations between respiratory indices and memory performance. Gregory
et al41 conducted an eight-year longitudinal study and
reported that sleep problems at ages five, seven, and nine were not
associated verbal memory performance at age 13. Kheirandish-Gozal et
al39 reported that the respiratory arousal index
predicted the slope of learning and delayed recall in children with SDB.
These results indicated that sleep fragmentation may influence the
challenges that children with SDB have when selecting efficient learning
strategies.39 A more recent study identified specific
sleep architecture features associated with NREM stage two sleep in SDB
that might influence memory consolidation.40 In
healthy children, sleep-dependent memory consolidation is associated
with NREM stage two (N2) sleep spindles. N2 sigma power is positively
associated with memory consolidation.40 In this study,
children with OSA had lower N2 sigma power than children with PS and
controls.40 Therefore, N2 sigma power might serve as a
biomarker of neurocognitive challenges in pediatric SDB.
The literature reviewed above revealed multiple discrepancies regarding
memory performance in children with SDB. A number of the studies were
limited by small sample sizes.40 In addition, most of
these studies defined SDB and SDB severity with different criteria,
making it challenging to compare results across studies. While some of
these studies recruited participants from the general
population,17,19 others included clinical samples of
children referred for concerns regarding
SBD,16,20,39-40 which may create potential referral
bias.