Persistent olfactory dysfunction associated with poor sleep quality and anxiety in patients with long COVID

Ambient chemical and physical approaches for the modulation of sleep and wakefulness

Humans spend a third of their lives asleep. While the sleep-wake behaviors are primarily modulated by homeostasis and circadian rhythm, several ambient chemical and physical factors, including light, sound, odor, vibration, temperature, electromagnetic radiation, and ultrasound, also affect sleep and wakefulness. Light at different wavelengths has different effects on sleep and wakefulness. Sound not only promotes but also suppresses sleep; this effect is mediated by certain nuclei, including the pedunculopontine nucleus and inferior colliculus. Certain sleep-promoting odorants regulate sleep through the involvement of the olfactory bulb and olfactory tubercle. In addition, vibrations may induce sleep through the vestibular system. A modest increase in ambient temperature leads to an increase in sleep duration through the involvement of the preoptic area. Electromagnetic radiation has a dual effect on sleep-wake behaviors. The stimulation produced by the ambient chemical and physical factors activates the peripheral sensory system, which converts the chemical and physical stimuli into nerve impulses. This signal is then transmitted to the central nervous system, including several nuclei associated with the modulation of sleep-wake behaviors. This review summarizes the effects of ambient chemical and physical factors on the regulation of sleep and wakefulness, as well as the underlying neurobiological mechanisms.

Psychological Distress in Patients with Long-lasting COVID-19 Olfactory Dysfunction

ObjectiveThe aim of this study was to investigate the psychological distress associated with long-lasting COVID-19 olfactory dysfunction (OD).MethodsPatients with an OD lasting for more than 6 months were consecutively recruited from the Dour Medical Center (Belgium) from August 2023 to January 2024. The olfaction was investigated with the Olfactory Disorder Questionnaires (ODQ) and the threshold, identification, and discrimination (TDI) testing. General Anxiety Disorder (GAD-7) and Patient Health Questionnaire (PHQ-9) were used to investigate the psychological distress of patients. The olfactory and psychological outcomes of patients were compared with a group of individuals without OD.ResultsA total of 220 patients and 102 asymptomatic individuals completed the evaluations. The mean duration of OD was 31.1 ± 25.1 months. The mean GAD-7 and PHQ-9 scores were significantly higher in OD patients than in asymptomatic individuals (P < 0.008). The OD patient prevalence of mild-to-severe depression (51.2% vs. 44.1%) and mild-to-severe anxiety (39.5% vs. 32.4%) disorders was significantly higher than asymptomatic individuals. Severe anxiety was associated with the presence of anosmia. GAD-7 and PHQ-9 scores were higher in females than in males. The severity of depression (PHQ-9) and anxiety (GAD-7) was significantly associated with the severity of OD (ODQ) and nasal symptoms (SNOT-22).ConclusionThe presence of a long-lasting OD in patients consulting in otolaryngology is associated with psychological distress. While the causality relationship remains unclear, depression and anxiety symptoms must be investigated in this subgroup of patients with long COVID-19.

Depression, Anxiety, and Neuropsychiatric Symptom Burden in a Longitudinal Cohort with Persistent Psychophysical Post-COVID Olfactory Dysfunction

BACKGROUND/OBJECTIVES

Olfactory dysfunction (OD) is associated with a variety of neurologic deficits and impacts socialization decisions, mood, and overall quality of life. As a common symptom comprising the long COVID condition, persistent COVID-19-associated olfactory dysfunction (C19OD) may further impact the presentations of neuropsychiatric sequelae. Our study aims to characterize the longitudinal burden of depression, anxiety, and neuropsychiatric symptoms in a population with C19OD.

METHODS

Individuals with perceived C19OD completed a psychophysical screening evaluation of their sense of smell using the comprehensive Sniffin' Sticks olfactory assessment. Only those with validated psychophysical OD were included in this prospective longitudinal study for baseline and one-year follow-up. Participants also completed PHQ-9, Beck Anxiety Inventory (BAI), and neuropsychiatric symptom questionnaires at each time point. Anxiety, depression, and neuropsychiatric symptom prevalence was calculated and compared between time points with Pearson's chi-squared, Fisher's exact, and Wilcoxon rank sum tests.

RESULTS

Each neuropsychiatric symptom evaluated in this study was reported by 13-49% of longitudinal cohort participants at both baseline and follow-up, except for seizure (0% at baseline and follow-up) and word-finding difficulty (61-68% at baseline and follow-up). Word-finding and focus difficulties were the most commonly reported symptoms. In total, 41% of participants reported some level of depression at baseline and 38% of participants reported depression at one-year follow-up, while 29% and 27% of participants reported some level of anxiety at respective time points.

CONCLUSIONS

Individuals with C19OD are at risk for developing persistent neuropsychiatric conditions. These neurologic and psychiatric sequelae are persistent with repeated longitudinal assessment, even at nearly 2.5 years following initial COVID-19 diagnosis.

The effects of sleep quality on loneliness among older adults: cohort analysis from the life course perspective

BACKGROUND

Using cohort analysis to examine the effects of sleep quality on loneliness among older adults from the life course perspective.

METHODS

The hierarchical age-period-cohort growth curve model was used to analyze the data from the 2005-2018 Chinese Longitudinal Healthy Longevity Survey (CLHLS).

RESULTS

(1) Loneliness has a 'U' curve relationship with age, but with the rate of increase gradually slowing down. (2) There were significant differences in loneliness across birth cohorts, with younger cohorts having higher predicted loneliness than older cohorts at the same age. (3) The influence of different sleep quality on loneliness showed a trend of increasing with age. (4) There were no significant differences in the impact of sleep quality on loneliness in different cohorts.

CONCLUSIONS

This study has identified heterogeneity in loneliness, emphasising the need for a diversified intervention approach. Sleep quality has a protective effect on loneliness and is easy to assess, making it an important intervention tool. In addition, it is imperative to account for the influences of age and cohort effects when formulating intervention strategies.

Effect of long COVID-19 syndrome on health-related quality of life: a cross-sectional study

Purpose

This study aimed to assess the association of anxiety, headache, and insomnia on the QoL of patients with long COVID-19.

Methods

We conducted a cross-sectional survey between August 2020 and March 2023. A total of 200 participants were eligible, 53 were excluded and 147 patients with long COVID were included. QoL was evaluated across eight domains using the 36-Item Short Form Health Survey (SF-36). Standardized protocols including the Beck Anxiety Inventory (BAI) (n = 103), Pittsburgh Sleep Quality Index (PSQI) (n = 73), and Migraine Disability Assessment (MIDAS) (n = 67) were also used.

Results

Participants with sleep disorders had significantly lower Vitality (p < 0.001). Participants with anxiety disorders had significantly lower Vitality (p = 0.001), poorer Mental Health (p = 0.008), and more severe Bodily Pain (p = 0.008). Participants with headache had significantly lower Vitality (p = 0.032), poorer Mental Health (p = 0.036), and poorer Physical Functioning (p = 0.016). Participants with both headache and anxiety had significantly lower Vitality (p = 0.005) and Mental Health (p = 0.043) domain scores. Correlation analysis revealed that higher scores for anxiety, sleep disorder, and headache were independently correlated with poorer QoL across various domains. The presence of sleep disorder was associated with a fourfold increase in risk of experiencing diminished Vitality (odds ratio [OR]4.47; 95% CI 1.01-19.69; p = 0.048).

Conclusion

Participants with anxiety, sleep, and headache disorders tended to have a worse QoL. The Vitality and Mental Health domains were the most adversely affected in patients with long COVID. Sleep disorders were associated with a fourfold increase in the risk of poor Vitality.

Poor sleep quality may trigger cognitive deficits after recovery from COVID-19

Objective

In the present study, we aimed to assess the cognition of post-COVID-19 condition (PCC) participants in relation to their subjective sleep quality (Pittsburgh Sleep Quality Index, PSQI) and to analyse possible moderators of this effect, such as quality of life (European Quality of Life-5 Dimensions, EQ-5D), fatigue (Chadler Fatigue Questionnaire, CFQ), cognitive reserve (Cognitive Reserve Questionnaire, CRC), and subjective cognitive complaints (Memory Failures of Everyday Questionnaire, MFE-30).

Methods

We included 373 individuals with PCC and 126 healthy controls (HCs) from the NAUTILUS Project (NCT05307549 and NCT05307575) who were assessed with a comprehensive neuropsychological battery and various questionnaires.

Results

We found that PCC participants with poor sleep quality had a 4.3% greater risk of immediate verbal memory deficits than those with good sleep quality, as indicated by the greater odds ratio (OR) of 1.043 and confidence interval (CI) of 1.023-1.063. Additionally, their risk of immediate verbal memory disorders was multiplied by 2.4 when their EQ-5D score was low (OR 0.33; CI 0.145-0.748), and they had a lower risk of delayed visual memory deficits with a greater CRC (OR 0.963; CI 0.929-0.999). With respect to processing speed, PCC participants with poor sleep quality had a 6.7% greater risk of deficits as the MFE increased (OR 1.059; CI 1.024-1.096), and the risk of slowed processing speed tripled with a lower EQ-5D (OR 0.021; CI 0.003-0.141).

Conclusion

These results indicate that poor subjective sleep quality is a potential trigger for cognitive deficits. Therapeutic strategies to maximize sleep quality could include reducing sleep disturbances and perhaps cognitive impairment in PCC individuals.

fNIRS a novel neuroimaging tool to investigate olfaction, olfactory imagery, and crossmodal interactions: a systematic review

Olfaction is understudied in neuroimaging research compared to other senses, but there is growing evidence of its therapeutic benefits on mood and well-being. Olfactory imagery can provide similar health benefits as olfactory interventions. Harnessing crossmodal visual-olfactory interactions can facilitate olfactory imagery. Understanding and employing these cross-modal interactions between visual and olfactory stimuli could aid in the research and applications of olfaction and olfactory imagery interventions for health and wellbeing. This review examines current knowledge, debates, and research on olfaction, olfactive imagery, and crossmodal visual-olfactory integration. A total of 56 papers, identified using the PRISMA method, were evaluated to identify key brain regions, research themes and methods used to determine the suitability of fNIRS as a tool for studying these topics. The review identified fNIRS-compatible protocols and brain regions within the fNIRS recording depth of approximately 1.5 cm associated with olfactory imagery and crossmodal visual-olfactory integration. Commonly cited regions include the orbitofrontal cortex, inferior frontal gyrus and dorsolateral prefrontal cortex. The findings of this review indicate that fNIRS would be a suitable tool for research into these processes. Additionally, fNIRS suitability for use in naturalistic settings may lead to the development of new research approaches with greater ecological validity compared to existing neuroimaging techniques.