JKBF bestows second Biological Research Award at Suicide Summit

In October JKBF was pleased to partner with the International Academy of Suicide Research (IASR) and the American Foundation for Suicide Prevention (AFSP) in giving an award in support of an early career scientist who focuses on exploring biological contributors to suicide. At the virtual 2021 International Summit on Suicide Research we presented the second James Kirk Bernard Foundation Award for Excellence in the Biological Exploration of Suicide to Nikolj Høier in recognition of his presentation Association of Hospital-Diagnosed Sleep Disorders with Suicide: A Nationwide Cohort Study.

This year we were excited to see a variety of candidate abstracts from young investigators exploring biological factors ranging from sleep, to traumatic brain injury, air pollution, and inflammatory markers. Selected from a pool of early career researchers presenting innovative biological studies, Mr. Høier was chosen for his work investigating a role for sleep disorders in suicide risk.

Mr. Høier worked with an esteemed team at the Danish Research Institute for Suicide Prevention to explore the national registry data and found that higher suicide rates occurred in individuals suffering from narcolepsy and sleep apnea. Mr. Høier is a medical student at The University of Copenhagen and a Master of Science by Research in Psychiatry student at the University of Edinburgh. His main area of interest is in how sleep disturbance and disorders, as well as sleep medications, affect risk for suicide. We wish Mr. Høier success in his efforts and look forward to his future contributions in suicide prevention research.

JKBF appreciates the collaboration with IASR and AFSP and the efforts of Gil Zalsman and Jill Harkavy-Friedman in the selection process and in making this award possible. Mr. Høier received an honorarium and will receive an award featuring a piece of Jamie’s art, and we look forward to meeting him in person at a future scientific gathering.

From the Scientist:

Summary of Presentation “Association of Hospital-Diagnosed Sleep Disorders with Suicide: A Nationwide Cohort Study”

By Nikolaj Kjær Høier

In collaboration with an amazing group of senior researchers, including Trine Madsen, Adam Spira, Keith Hawton, Michael E. Benros, Merete Nordentoft, and Annette Erlangsen, I set out to study the possible link between sleep and suicide at DRISP – The Danish Research Institute for Suicide Prevention. Our effort was motivated by the fact that sleep disturbances and disorders have often been linked to suicide.^1-3 However, the evidence has been restricted to data sources with certain limitations. Death by suicide is, fortunately, a rare event, but this implies that large sample sizes are needed to study this outcome. For this reason, our insights have been restricted to outcomes that are more frequent, such as suicide ideation or self-harm behavior.^4,5 We thought that analyses of the national Danish registries with individual-level data on more than 6 million individuals who have lived in Denmark since the 1980s would be able to answer this question.

Our aim was to examine, in a population-based cohort study, whether persons who had been diagnosed with a sleep disorder had a higher suicide rate than persons who had not been diagnosed with such a disorder. We were able to analyze this using the Danish national linkage data, which covers the entire population and combines a range of data, for instance socio-demographic information, hospital diagnoses, and data on causes of death.

Spanning the period of 1980-2016, we investigated 7,362,727 individuals, age 15 or older, who lived in Denmark. Among these 35,483 were diagnosed with a sleep disorder in a hospital setting, predominantly narcolepsy and sleep apnea. Investigation of cause of death revealed that people who had been diagnosed with a sleep disorder were found to have higher rates of suicide than those not diagnosed. For males a 1.55 higher rate and for females 2.19 higher rate for suicide was noted, showing that the risk for suicide amongst those diagnosed is significantly higher than those not diagnosed. This association was confirmed when adjusting for relevant covariates, such as sex, socio-economic factors, previous history of mental disorders, and previous suicide attempts. We found that males and females suffering from narcolepsy had increased rates of suicide in adjusted analyses, and a link between sleep apnea and suicide risk was established for males. Our results indicated that the highest risk for suicide was seen within 6 months of sleep disorder diagnosis.

It is important to emphasize that suicide is a rare event, and it was only 1.17% of those diagnosed with sleep disorders who died by suicide. Although the group of persons with sleep disorders has a higher risk of suicide, this does not mean that many of these people, in absolute numbers, will die by suicide.

Suffering from sleep disorders can, however, be very distressing, dysregulating, and affect daily routines. Sleep disorders are also a symptom of mental disorders, which in turn are linked to higher rates of suicide. We also identified that those who were diagnosed with a mental disorder after their sleep disorder diagnosis had a high rate of suicide than those who were diagnosed with a mental disorder before their sleep disorder. This could suggest that when a sleep disorder is severe, it can lead to mental health problems and thus increase the risk of suicide. For this reason, it is important to ensure that the diagnostics of sleep disorders includes effective and attentive treatment, and an assessment of and ongoing attention to mental health. We cannot exclude that some of the persons with sleep disorders who died by suicide might have suffered from undiagnosed mental disorders. Our findings allude to the importance of conducting a thorough diagnostic assessment when people suffer from disturbed sleep over longer periods.

Seemingly, our findings provide the first documentation for an association between narcolepsy and suicide risk. Being a chronic sleep disorder, narcolepsy is also an autoimmune disorder. It is caused by a lack of orexin-producing neurons, orexin being important in the systems that maintain our wakefulness. People suffering narcolepsy experience spontaneous sleep attacks which have a severe impact on daily life and put a limit on the person’s daily activities, for instance, driving a car or walking up and down a set of stairs.

Individuals who are diagnosed with sleep apnea often suffer from other comorbidities, such as cardiovascular disorders and obesity. People with sleep apnea have a reduced uptake of oxygen during their sleep, which can induce hypoxia (oxygen deprivation) to the brain, with minor brain damage being one of the more severe potential consequences. The fact that as many as 3-6% of adults may suffer from sleep apnea underscores the need for a better understanding of how this disorder might be linked to suicide.

It is likely that people with insomnia are most often treated in primary care at general practitioners. Therefore, our findings can only provide information on individuals who were so severely affected by a sleep disorder that they would end up being referred to hospital setting. Other sleep disorders that were less frequent were compiled in our analysis and a mixed group of sleep disorders comprised of disorders such as insomnia, nightmare, sleep walking and disturbed circadian rhythm were also found to have higher risk of suicide. However, seeing how this is a diagnosis group with a high degree of heterogeneity, it is hard to draw any precise conclusion from this finding. Having been diagnosed by a medical doctor specialized in sleep disorders is likely to have a higher clinical validity, which means that there may be sleep disturbances in others who died by suicide but were not diagnosed in hospital settings.

Our findings point to a higher risk of suicide among persons with severe forms of sleep disorders. A better understanding of the neurobiological pathology of persons suffering from narcolepsy and sleep apnea might help elucidate the intricate relationship between sleep disorders and suicide.

1. Liu RT, Steele SJ, Hamilton JL, et al. Sleep and suicide: A systematic review and meta-analysis of longitudinal studies. Clin Psychol Rev. 2020;81:101895.
2. Porras-Segovia A, Perez-Rodriguez MM, Lopez-Esteban P, et al. Contribution of sleep deprivation to suicidal behaviour: A systematic review. Sleep Med Rev. 2019;44:37-47.
3. Bernert RA, Joiner TE, Jr., Cukrowicz KC, Schmidt NB, Krakow B. Suicidality and sleep disturbances. Sleep. 2005;28(9):1135-1141.
4. Harris LM, Huang X, Linthicum KP, Bryen CP, Ribeiro JD. Sleep disturbances as risk factors for suicidal thoughts and behaviours: a meta-analysis of longitudinal studies.
5. Timkova V, Nagyova I, Reijneveld SA, et al. Suicidal ideation in patients with obstructive sleep apnoea and its relationship with disease severity, sleep-related problems and social support. J Health Psychol. 2020;25(10-11):1450-1461.