O3298: Salivary microRNA Biomarkers Reflect the Complex Interrelationship between Concussion, Sleep Related Symptoms, and Psychological Health Related Symptoms

Background: Psychological health symptoms (ie depressive or anxiety symptoms) and sleep disruptions are common and interrelated symptoms following concussion. There is a strong need to identify factors that predict these symptoms following concussion. Salivary micro-RNAs (miRNAs) are known biomarkers for concussion and are also associated with both sleep quality and psychological health. Therefore, the purpose of this study was to identify salivary miRNAs that were correlated with sleep health symptoms and/or psychological health symptoms and to test whether these miRNAs were differentially expressed between a group of participants with concussion versus uninjured controls.

Methods: We performed a secondary analysis of salivary miRNA and concussion symptom data from n=272 concussion cases (median 2.5 days post-injury) and n=153 non-concussion controls. miRNAs were quantified from salivary samples using the Illumina HiSeq 2500 platform. Concussion symptoms were quantified with the Post-Concussion Symptom Inventory (PCSI), a self-reported instrument that quantifies 20 concussion related symptoms. Spearman rank correlations tested the correlation between levels of individual miRNAs and PCSI sleep related symptoms (“Drowsiness” and “Trouble falling asleep”) as well as PCSI psychological health related symptoms (“More Emotional”, “Irritability”, and “Nervous or Anxious”). Wilcoxon rank sum tests were used to test for differences in miRNA levels between concussion cases and controls. The Benjamini-Hochberg method was used to account for multiple testing. miRNA associations were evaluated at the adjusted alpha level of 0.05. The miRPath V4.0 pathway analysis program, using the microclip (brain) and microT-CDS algorithms (threshold >0.80), was used to test whether the genes targeted by miRNAs identified in our analysis were enriched within brain-related pathways.

Results: We identified 90 miRNAs that were differentially expressed between concussion cases and controls, 15 miRNAs that were correlated with sleep symptoms, 29 that were correlated with psychological health symptoms, and 4 miRNAs were correlated with both sleep and psychological health symptoms (miR-361-5p, miR-4510, miR-193a-3p, miR-3074-5p, Figure 1). Two miRNAs, miR-4510 and miR-193a-3p, were differentially expressed between cases and controls and were correlated with both sleep and psychological health symptoms (Table 1). Downstream gene targets of miRNAs correlated with both sleep and psychological health symptoms were FDR significantly enriched within 85 brain pathways including “spinocerebellar ataxia”, “dopaminergic synapse”, “axon guidance”, and “circadian entrainment”.

Conclusion: Salivary miRNAs were disrupted following concussion and were associated with both sleep and psychological health related symptoms. miRNAs identified in the current analysis target genes that are enriched within relevant brain related pathways (“circadian entrainment”) and thus, miRNAs provide a potential mechanistic link between concussion and sleep symptoms. To evaluate the candidate miRNAs (miR-4510 and miR-193a-3p) as prognostic biomarkers, additional research is needed to confirm the temporality of the relationship between concussion, alterations in miRNA levels, and the onset of sleep and/or psychological health related symptoms.