Association of Sleep Spindle Rate With Memory Consolidation in Children With Rolandic Epilepsy
Hunki Kwon1,2, Dhinakaran M Chinappen1,3, Elizabeth A Kinard1
1Department of Neurology, Massachusetts General Hospital, Boston.
Insights
Children with active Rolandic epilepsy (RE) show impaired memory consolidation, linked to reduced sleep spindles in the brain. This finding may help diagnose cognitive issues in RE and guide new therapies.
Area of Science:
- Pediatric Neurology
- Sleep Medicine
- Cognitive Neuroscience
Background:
- Rolandic epilepsy (RE) is the most common focal epilepsy in children, often associated with cognitive deficits.
- Sleep spindles, crucial for memory consolidation, are reduced in RE.
- The link between reduced sleep spindles and cognitive dysfunction in RE requires further investigation.
Purpose of the Study:
- To investigate sleep-dependent memory consolidation in children with RE.
- To determine if impaired memory consolidation in RE is associated with reduced sleep spindle activity.
Main Methods:
- A prospective case-control study involving children with RE and age-matched controls.
- Memory consolidation assessed using the motor sequence task (MST) during a nap.
- Sleep spindles measured via high-density EEG using an automated detection method.
Main Results:
- Children with active RE exhibited significantly decreased memory consolidation compared to controls and those with resolved RE.
- Active RE cases showed reduced sleep spindle rates in the centrotemporal region compared to controls.
- Sleep spindle rate, not spike rate or spike-wave index, correlated with sleep-dependent memory consolidation.
Conclusions:
- Children with active RE experience impaired sleep-dependent memory consolidation.
- This impairment correlates with reduced sleep spindle rates, suggesting a potential biomarker.
- Findings may guide therapeutic strategies for cognitive dysfunction in RE and similar epilepsy syndromes.
Background And Objectives:
Rolandic epilepsy (RE), the most common childhood focal epilepsy syndrome, is characterized by a transient period of sleep-activated epileptiform activity in the centrotemporal regions and variable cognitive deficits. Sleep spindles are prominent thalamocortical brain oscillations during sleep that have been mechanistically linked to sleep-dependent memory consolidation in animal models and healthy controls. Sleep spindles are decreased in RE and related sleep-activated epileptic encephalopathies. To further evaluate the association between this electrographic biomarker and cognitive dysfunction in this common disease, we investigate whether children with RE have deficient sleep-dependent memory consolidation and whether impaired memory consolidation is associated with reduced sleep spindles in the centrotemporal regions.
Methods:
In this prospective case-control study, children were trained and tested on a validated probe of memory consolidation, the motor sequence task (MST). Sleep spindles were measured from high-density EEG during a 90-minute nap opportunity between MST training and testing using an automated sleep spindle detector validated for use in children with and without epilepsy.
Results:
Twenty-three children with RE (9 with active disease, 5F, age 6.9-12.8 years; 14 with resolved disease, 8F, age 8.8-17.8 years) and 19 age-matched and sex-matched controls (8F, age 6.9-18.7 years) were enrolled. Children with active epilepsy had decreased memory consolidation compared with control children (p = 0.001, mean percentage reduction 25.7%, 95% CI 10.3%-41.2%) and compared with children with resolved epilepsy (p = 0.007, mean percentage reduction 21.9%, 95% CI 6.2%-37.6%). Children with active epilepsy had decreased sleep spindle rates in the centrotemporal region compared with controls (p = 0.008, mean decrease 2.5 spindles per minute, 95% CI 0.7-4.4 spindles per minute). Spindle rate, but not spike rate or spike-wave index, correlated with sleep-dependent memory consolidation (p = 0.004, mean MST improvement of 3.9%, 95% CI 1.3%-6.4%, for each unit increase in spindles per minute).
Discussion:
Children with RE have impaired sleep-dependent memory consolidation during the active period of disease that correlates with a deficit in the sleep spindle rate. This finding identifies a noninvasive biomarker to aid diagnosis and a potential etiologic mechanism to guide therapeutic discovery of cognitive dysfunction in RE and related sleep-activated epilepsy syndromes.
