Cognitive Dysfunction in Insomnia Phenotypes: Further Evidence for Different Disorders

Michelle Olaithe; Melissa Ree; Nigel McArdle; Sara Donaldson; Maria Pushpanathan; Peter R Eastwood; Romola S Bucks

doi:10.3389/fpsyt.2021.688672

Cognitive Dysfunction in Insomnia Phenotypes: Further Evidence for Different Disorders

Front Psychiatry. 2021 Jul 19:12:688672. doi: 10.3389/fpsyt.2021.688672. eCollection 2021.

Authors

Michelle Olaithe¹, Melissa Ree^{1

2}, Nigel McArdle^{2

3}, Sara Donaldson¹, Maria Pushpanathan¹, Peter R Eastwood^{2

3

4}, Romola S Bucks^{1

5}

Affiliations

¹ School of Psychological Science, University of Western Australia, Perth, WA, Australia.
² Centre for Sleep Science, School of Human Sciences, University of Western Australia, Perth, WA, Australia.
³ Department of Pulmonary Physiology and Sleep Medicine, West Australian Sleep Disorders Research Institute, Sir Charles Gairdner Hospital, Nedlands, WA, Australia.
⁴ College of Medicine and Public Health, Flinders Health and Medical Research Institute, Flinders University, Bedford Park, SA, Australia.
⁵ School of Population and Global Health, University of Western Australia, Perth, WA, Australia.

Abstract

Study Objectives: To determine cognitive profiles in individuals with short sleep duration insomnia (SSDI) and normal sleep duration insomnia (NSDI; also, paradoxical insomnia), compared to healthy sleepers. Method: Polysomnographic (PSG) and neuropsychological data were analysed from 902 community-based Raine Study participants aged 22 ± 0.6 years of whom 124 met criteria for insomnia (53 with NSDI and 71 with or SSDI) and 246 were classified as healthy with normal sleep (i.e., without insomnia or other sleep disorders). Measurements of self- report (attention and memory) and laboratory-assessed (attention, episodic memory, working memory, learning, and psychomotor function) cognition and mood, and PSG-based sleep stages (% total sleep time; %TST) were compared between these 3 groups. Results: In comparison to the healthy sleeper group, both insomnia groups had poorer self-reported attention, memory, mood, and sleep, and poorer laboratory-assessed attention (inconsistency). The NSDI group had less consistent working memory reaction time than healthy-sleepers or those with SSDI. The SSDI group had more inconsistency in executive function (shifting), and showed greater %TST in stage N1 and N3, and less REM sleep than either healthy-sleepers or those with NSDI. Conclusions: Individuals with NSDI demonstrated greater working memory inconsistency, despite no laboratory assessed sleep problems, implicating early signs of pathophysiology other than disturbed sleep. Those with SSDI demonstrated different sleep architecture, poorer attention (inconsistency), and greater executive function (inconsistency) compared to healthy-sleepers and those with NSDI, implicating sleep disturbance in the disease process of this phenotype.

Keywords: cognition; insomnia; neuropsychology; paradoxical; phenotypes; short-sleep.