Exploring the relationship of sleep, cognition, and cortisol in sickle cell disease

Melanie Kölbel; Fenella J Kirkham; Ray K Iles; Hanne Stotesbury; Elizabeth Halstead; Celia Brenchley; Sati Sahota; Dagmara Dimitriou

doi:10.1016/j.cpnec.2022.100128

Exploring the relationship of sleep, cognition, and cortisol in sickle cell disease

Compr Psychoneuroendocrinol. 2022 Mar 4:10:100128. doi: 10.1016/j.cpnec.2022.100128. eCollection 2022 May.

Authors

Melanie Kölbel¹, Fenella J Kirkham^{1

2

3}, Ray K Iles^{4

5}, Hanne Stotesbury¹, Elizabeth Halstead², Celia Brenchley¹, Sati Sahota¹, Dagmara Dimitriou^{2

4}

Affiliations

¹ Clinical Systems Neuroscience Section, UCL Great Ormond Street Institute of Child Health, London, UK.
² Sleep Education and Research Laboratory, UCL Institute of Education, London, UK.
³ Clinical and Experimental Sciences, University of Southampton, Southampton, UK.
⁴ NISAD, Medicon Village, SE-223 81, Lund, Sweden.
⁵ Laboratory of Viral Zoonotics, Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge, CB3 0ES, UK.

Abstract

Background: Neurocognitive impairment is common in people with Sickle Cell Disease (SCD) and evidence is accumulating that sleep disturbances play a role. The interaction between cortisol and sleep in the general population is associated with cognition as well as general wellbeing but there are few data in SCD. We aimed to understand the relationship between cortisol and sleep in individuals with SCD and explored associations with cognition.

Methods: Forty-five participants of black heritage (SCD: N = 27, 9-29 years, 16 females; Controls: N = 18, 11-25 years, 13 females) were recruited from the community between 2018 - 2020. Participants completed standardized questionnaires about their sleep behaviour and wore actigraphy MotionWatch8 for 7 nights to assess nocturnal sleep patterns. Salivary cortisol samples were taken on wakening and 3 times after 14:00. Cognition was assessed using the Wechsler Intelligence Scales for children and adults.

Results: People with SCD took longer to fall asleep and experienced greater wake bouts, mobile minutes and fragmented sleep compared to controls. Although non-significant, people with SCD experienced lower morning cortisol, with a flattened diurnal cortisol ratio compared to controls. Interestingly, SCD participants, but not controls, with low diurnal variation scored lowest on processing speed (PSI) and perceptual reasoning index (PRI). A moderator analysis revealed that the effect of morning cortisol and diurnal cortisol ratio on PRI by group health (i.e., SCD and healthy controls) depended on sleep quality.

Discussion: Sleep and cortisol may play a crucial role in the expression of cognitive difficulties seen in SCD. This should be considered for the development of interventions to optimise cognitive functioning and sleep. This, in turn, could positively impact on secretion of cortisol and general health in SCD.

Keywords: Actigraphy; CAR, Cortisol awakening response; Cognition; Cortisol; DCR, Diurnal cortisol ratio; FCP, Flat cortisol profile; FI, Fragmentation index; NCP, Normal cortisol profile; OSA, Obstructive sleep apnoea; PLMS, Periodic limb movement syndrome; PRI, Perceptual Reasoning Index; PSI, Processing Speed Index; SCD, Sickle cell disease; SDB, Sleep disordered breathing; SES, Socioeconomic status; SOL, Sleep onset latency; Sickle cell; Sleep; Sleep disorders; VCI, Verbal Comprehension Index; WMI, Working Memory Index.