Studies show a link between obstructive sleep apnea, decreased mental processing powers, and an increased risk of blood clots and cancer.

A large study presented Monday at the International Conference of the European Respiratory Society (ERS) in Barcelona, ​​Spain, shows that people with obstructive sleep apnea (OSA) are at an increased risk of developing cancer.

A second study showed that obstructive sleep apnea is also associated with lower processing powers in the elderly; In particular, those aged 74 or older and men showed sharp declines on some cognitive tests. A third study found that patients with more severe obstructive sleep apnea were at increased risk of developing blood clots in their veins – a potentially life-threatening condition.

OSA is a common sleep disorder in which people have partial or complete blockage of their airways during sleep and stop breathing several times in the night. This can manifest as loud snoring, panting, choking, and daytime sleepiness. It is thought to affect at least 7-13% of the population. People who are overweight or obese, have diabetes, or who smoke or consume large amounts of alcohol are most at risk of developing obstructive sleep apnea.

Dr. Andreas Palm, senior researcher and consultant at Uppsala University, Sweden, who presented the first study, said: “It is already known that patients with obstructive sleep apnea have an increased risk of developing cancer but it is not clear whether this is due to OSA itself. or to cancer-related risk factors, such as obesity, cardiovascular disease, and lifestyle factors. Our results show that oxygen deprivation due to obstructive sleep apnea is independently associated with cancer.”

Dr. Palm and colleagues examined data from 62,811 patients five years before treatment for obstructive sleep apnea began in Sweden. Between July 2010 and March 2018, patients were treated with continuous positive airway pressure (CPAP), which provides positive air pressure through a mask to keep the airways open during sleep. The researchers linked this data to data from the Swedish National Cancer Registry and socioeconomic data from Statistics Sweden.

The researchers took into account factors that could influence the results such as body size, other health problems and socioeconomic status. They interviewed 2,093 patients with obstructive sleep apnea and a diagnosis of cancer up to five years prior to the diagnosis of obstructive sleep apnea with a control group of 2093 patients with obstructive sleep apnea but not cancer. They measured the severity of their obstructive sleep apnea (OSA) using the obstructive sleep apnea index (AHI), which measures the number of breathing disorders during sleep, or the oxygen desaturation index (ODI), which measures how many times per hour blood oxygen levels drop at 3 % for at least ten seconds or more.

“We found that patients with cancer had slightly more severe obstructive sleep apnea, as measured by a mean hypoventilation index of 32 versus 30, and an oxygen desaturation index of 28 versus 26,” he said. In further subgroup analysis, ODI was higher in patients with lung cancer (38 versus 27), prostate cancer (28 versus 24), and malignant melanoma (32 versus 25).

“The findings in this study highlight the need to consider untreated sleep apnea as a risk factor for cancer and for clinicians to be aware of the potential for cancer when treating patients with obstructive sleep apnea. However, expanding cancer screening to all patients is OSA is not justified or recommended by the results of our study.”

The study only looked at data from one time and cannot show that obstructive sleep apnea causes cancer, only that it is associated with it. Some important lifestyle factors such as physical activity and food preferences on an individual basis were not captured in the study. The main strength of the study lies in its large size and the high quality of data regarding the diagnosis of cancer and obstructive sleep apnea.

In the future, Dr. Palm and colleagues plan to increase the number of patients and follow up over time to study the potential effects of PAP therapy on cancer incidence and survival. “The association between obstructive sleep apnea and cancer is less well established than the association with cardiovascular disease, insulin resistance, diabetes and fatty liver disease,” he said. “Therefore, more research is needed, and we hope that our study will encourage other researchers to investigate this important topic.”

In a second presentation, Professor Raphael Heinzer, director of the Center for Investigation and Research on Sleep (CIRS) at the University of Lausanne, Switzerland, told Congress that the study by his colleague Dr. Nicolas Marchi showed that obstructive sleep apnea (OSA) was associated with a greater reduction. in the powers of mental processing over a period of five years.

Professor Heinzer and Dr. Nicolas Marchi of Lausanne University Hospital and colleagues studied subjects aged 65 and over from the general Lausanne population who were recruited into the CoLaus/PsyCoLaus and HypnoLaus studies between 2003 and 2008, and who were followed every five years. Years. A total of 358 participants took a sleep test to examine the presence and severity of obstructive sleep apnea when they joined the studies. During the first follow-up between 2009 and 2013, their mental processing abilities were also tested and another cognitive assessment was conducted during the second follow-up five years later.

Cognitive tests assessed global cognitive function (knowledge and reasoning skills), processing speed (the time taken to understand and interact with information), executive function (the ability to organize thoughts and activities, prioritize tasks and make decisions), verbal memory, language, and visual perception of spatial relationships between objects. (visual-spatial function).

Speaking before the conference, Dr Marchi said: “We found that obstructive sleep apnea, and in particular, lower oxygen levels during sleep due to obstructive sleep apnea, was associated with greater declines in global cognitive function, processing speed, executive function, and verbal memory. We also found that people aged 74 or older and men were more likely to have sleep apnea-related cognitive decline on some specific cognitive tests.

For example, the Stroop test, which measures processing speed and executive function, showed a sharp decline in people aged 74 and older compared to younger participants, and a verbal fluency test showed a sharp decline in only men but not women.

“This study demonstrates that the severity of sleep apnea and nocturnal oxygen deprivation contribute to cognitive decline in old age. It also shows that sleep apnea is associated with decreased specific cognitive functions, such as processing speed, executive function, and verbal memory., but not to a decline in all cognitive functions; For example, language and visuospatial function were not affected,” said Dr. Marchi.

“People with obstructive sleep apnea and clinicians should be aware that obstructive sleep apnea may play a role in cognitive decline. However, to date, treatment of obstructive sleep apnea with continuous positive airway pressure (CPAP) has not been clearly demonstrated to prevent cognitive decline.” And our study suggests that perhaps not all OSA patients have the same risk of cognitive decline; there may be a subset of patients, especially those with more nocturnal hypoxia but also older patients and men, who may be at greater risk of cognitive decline associated with OSA. “.

The researchers plan to analyze data on the impact of obstructive sleep apnea after ten years to learn more about who is most at risk of cognitive decline associated with obstructive sleep apnea. Dr. Marchi suggests that conducting a randomized controlled trial with these patients in order to investigate the effect of CPAP on cognition should be the next step thereafter.

The study’s strengths include that it followed people over five years, that OSA was evaluated by a “gold standard” polysomnography test, and that several tests were used to assess a range of cognitive processes. Limitations include that participants were relatively healthy, without severe cognitive impairment or dementia and that OSA was only assessed at the start of the study.

A third study, presented by Professor Wojciech Trzepizur, from Angers University Hospital in France, showed that patients with more severe OSA, as measured by AHI and signs of nocturnal oxygen deprivation, were more likely to develop venous thromboembolism (VTE). Of the 7,355 patients who were followed up over six years, 104 developed VTEs.

“This is the first study to look at the relationship between obstructive sleep apnea and the occurrence of unexplained venous thromboembolism. We found that those who spent more than 6% of the nights with blood oxygen levels below 90% of the normal range,” Professor Trezebezor said. There is a twofold risk of developing VTE compared to patients without hypoxia.” “Further studies are needed to see if appropriate treatment of obstructive sleep apnea, for example with CPAP therapy, may reduce the risk of VTE.” venous thromboembolism in patients with marked nocturnal oxygen deprivation.

Professor Winfried Randrath, of the Bethanian Hospital at the University of Cologne in Germany, is head of the ERS Group specializing in sleep-disorders of breathing and was not involved in the three studies. He commented, “These three studies show troubling associations between OSA and important diseases that affect survival and quality of life. The data support the association of OSA with cancer, venous thromboembolism and mental health. While they cannot prove that OSA causes any something. Of these health problems, people should be aware of these links and should try to make lifestyle changes in order to reduce the risk of developing OSA, for example, by maintaining a healthy weight. We look forward to further research that It may help clarify whether obstructive sleep apnea may be causing some of the health issues shown in these studies.”