Poster #1 - Associations Between Sleep, Memory, and Hippocampal Volume in 4- to 8-year-olds

• In Event: 2-163 - Poster Session 08
  In Poster Session: PS 08 Section - Attention, Learning, Memory

Integrative Statement

The average child spends approximately 12 hours of every day asleep (National Sleep Foundation, 2018). Though sleep is an instrumental factor of development, there are currently no formal recommendations regarding sleep routines in childhood (e.g., from American Academy of Pediatrics). In adults, extreme variations in sleep have been shown to impact cognition and memory, likely due to the toll it takes on brain structures such as the hippocampus (Goel, Rao, Durmer & Dinges, 2009). The hippocampus is a structure in medial temporal lobes of the brain that is thought to be primarily responsible for consolidation (or ‘packaging’) of long-term memory and has been linked with various stages of sleep. For example, procedural aspects of our memories are consolidated during the REM cycle, whereas declarative memories are consolidated during slow-wave sleep (Marshall & Born, 2007). The connection between sleep, memory, and hippocampus functionality is well established in adults (Rasch & Born, 2013), however, the nature and manifestation of this important link in early childhood when both sleep and memory show large developmental changes is not fully understood. The present study sought to address this gap by examining behavioral measures of children’s general cognitive and memory ability, parent-reported measures of sleep, and structural magnetic resonance images of children’s brains to examine associations between these factors.

This study collected data from four facets of development from 200 children ages 4-8 years. The memory test was adapted from the Children’s Memory Scale (Cohen, 1997). The children were tested on their memory of details from a story immediately after encoding, after one hour, and after one week. The intelligence measure used subtests from age-appropriate standardized tests (Wechsler Intelligence Scale for Children-Fourth Edition and Wechsler Preschool and Primary Scale of Intelligence). Scores were obtained from the block and vocabulary design subtest. Sleep habits were recorded by the child’s caregiver, detailing the sleep habits and sleep duration of the child using the Child Sleep Habits Questionnaire (Owens et al, 2000). Hippocampal volume was obtained from a T1-weighted MRI scan (.9mm3) using Freesurfer and Automated Segmentation Adapter Tool (ASAT) (Riggins et al., 2017).

Preliminary findings from partial correlations controlling for age show that there is a positive correlation between sleep duration and source memory (Figure 1) (r(177)= .153, p = .041), a negative correlation between sleep duration and the volume of the right hippocampal body (Figure 2) (r(170)= - .168, p = .028), and no correlation between sleep duration and block IQ or vocabulary IQ (r(180)= .103, p = .168), (r(180)= .050, p = .502). Although we know that age and brain development are important for memory in early childhood development (Riggins, 2014), our findings suggest that sleep is also connected to those developments. In contrast, sleep is not related to individual differences in general intelligence. These results could explain the large individual differences observed in memory ability during early childhood. Future analyses will further examine the intricacies of whether sleep mediates associations between memory and hippocampal volume and whether these associations vary across this age range.

Authors

• Elianna Lopez, University of Maryland, College Park
  Presenting Author

• Tracy Riggins, University of Maryland
  Non-Presenting Author