Uppsala, Sweden – Snorers may have an increased risk of cancer, cardiovascular disease and dementia, according to a new study. Obstructive sleep apnea, with snoring as its main symptom, cuts off oxygen supply — fueling tumors, blood clots and brain cell loss, scientists in Sweden say.
According to the American Medical Association, obstructive sleep apnea (OSA) affects about 30 million Americans — although only 6 million have been diagnosed. This condition causes the walls of the throat to relax and narrow, interrupting normal breathing several times a night. People who are overweight are especially prone to OSA. Precautions include losing weight or wearing a mask in bed that blows air down the back of your throat.
The findings, presented at the European Respiratory Society (ERS) meeting in Barcelona, could lead to screening programmes. They are based on three European studies.
“Patients with obstructive sleep apnea are known to have an increased risk of cancer, but it is unclear whether this is due to OSA itself or to cancer-related risk factors such as obesity, cardiometabolic disease and lifestyle factors,” Uppsala University Researcher and senior advisor Dr. Andreas Palm said in a statement. “Our findings suggest that hypoxia due to OSA is independently associated with cancer.”
The study authors analyzed data from 62,811 Swedes who started using CPAP (continuous positive airway pressure) masks for obstructive sleep apnea five years ago. They combined it with information from the Swedish National Cancer Registry, taking into account body size, other health concerns and socioeconomic status. It allowed them to match 2,093 patients with OSA and those diagnosed with cancer five years before OSA diagnosis to a control group of 2,093 patients with OSA but no cancer.
Severity is measured with the Apnea Hypopnea Index (AHI) – which counts breathing disturbances during sleep – or the Oxygen Saturation Index (ODI), which measures hourly blood levels falling for 10 seconds or more At least 3% of the times.
“We found that cancer patients had slightly more severe OSA, as measured by mean apnea-hypopnea index of 32 versus 30 and oxygen saturation index of 28 versus 26,” Palm said. “In a further analysis of the subgroups, the ODI was higher in patients with lung cancer (38 vs 27), prostate cancer (28 vs 24) and malignant melanoma (32 vs 25).
“The results of this study underscore the need to consider untreated sleep apnea as a risk factor for cancer and to make physicians aware of the possibility of cancer when treating patients with OSA,” Palm continued. “However, our findings do not justify or recommend expanding cancer screening to all patients with OSA.”
The researchers plan to increase the number of patients and follow them over time to study the potential impact of CPAP treatment on cancer incidence and survival.
“Compared to the links between heart and vascular disease, insulin resistance, diabetes and fatty liver disease, the link between OSA and cancer is less clear,” Palm added. “Therefore, more research is needed, and we hope our study will encourage other researchers to study this important topic.”
Effects of Obstructive Sleep Apnea on the Brain
The second study identified a link between OSA and a greater decline in brain power over five years. It is based on a sleep test conducted by 358 people over the age of 65 in Switzerland. Visual perception of global cognitive and executive function, verbal memory, language and spatial relationships was also assessed.
“We found that OSA, especially low oxygen levels due to OSA during sleep, was associated with a greater decline in overall cognitive function, processing speed, executive function and verbal memory,” said Dr Nicola Marchi from the University of Lausanne. “We also found that , people 74 years and older and men are at higher risk for sleep apnea-related cognitive decline on certain cognitive tests.”
For example, the Stroop test, which measures processing speed and executive function, showed greater declines in people 74 and older than in younger participants. Language fluency showed a larger decline for men, but not for women.
“This study shows that the severity of sleep apnea and nocturnal hypoxia contributes to cognitive decline in older age,” Dr. Marchi said. “It also showed that sleep apnea was associated with declines in specific cognitive functions, such as processing speed, executive function, and verbal memory, but not with declines in all cognitive functions; for example, language and visuospatial function were unaffected.
“People and physicians with OSA should be aware that OSA may play a role in cognitive decline. However, to date, it has not been definitively demonstrated that treating OSA with continuous positive airway pressure (CPAP) prevents cognitive decline,” Marchi said. “Our study suggests that not all patients with OSA may 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 face greater OSA-related Cognitive decline risk.”
The researchers plan to analyze data on the effects of OSA in a decade to learn more about who is most likely to experience cognitive decline. Dr. Marchi suggested that a randomized controlled trial of these patients to study the effects of CPAP on cognition should be the next step after that.
Higher risk of blood clots
A third study showed that patients with more severe obstructive sleep apnea were more likely to develop blood clots (venous thromboembolism) that could trigger a heart attack or stroke, as measured by AHI and markers of nocturnal hypoxia.
“This is the first study to investigate the relationship between obstructive sleep apnea and the incidence of unprovoked venous thromboembolism,” explains Wojciech Trzepizur of Angers University Hospital in France. “We found that those with less than 90 percent of the normal blood oxygen at night had nearly twice the risk of developing VTE more than 6 percent of the time compared to patients without hypoxia. Further research is needed to To determine whether adequate treatment of OSA, such as treatment with CPAP, can reduce the risk of VTE in patients with significant nocturnal hypoxia.”
Results were based on 7,355 patients followed over 6 years, 104 of whom developed VTE.
Professor Winfried Randerath of the Bethanien Hospital of Cologne University in Germany, who leads the ERS sleep-disordered breathing expert group, was not involved in the three studies. “These three studies show a worrying association between obstructive sleep apnea and important conditions that affect survival and quality of life,” he said. “These data support the association of sleep apnea with cancer, venous thromboembolism and mental health. While they cannot prove that OSA causes any of these health problems, people should be made aware of these links and should try lifestyle changes to lower them Risk of OSA, for example, by maintaining a healthy weight.
“However, if OSA is suspected, definitive diagnosis and treatment should be initiated,” he stressed. “We look forward to further research that may help clarify whether OSA may contribute to some of the health problems seen in these studies.”
Southwest News Service writer Mark Waghorn contributed to this report.