lena peretz lavie 311.
(photo credit: Yoav Bachar)
Sleep apnea syndrome – in which sufferers stop breathing momentarily many times during the night – has for many years been regarded as a major risk factor for clogging of the coronary arteries and other heart diseases. But now, Technion-Israel Institute of Technology President Prof. Peretz Lavie – a psychologist and one of the country’s leading sleep medicine experts – and his wife and fellow researcher cell biologist, Dr. Lena Lavie, have found that in elderly people, moderate apnea may in fact extend their lives rather than shorten it.
The Lavies’ research, based on the study of 611 individuals with a mean age of 70 and a follow-up period of about five years, has just been published in the Journal of Sleep Research of the European Sleep Research Society. The reasoning has been confirmed separately by German researchers at Heinrich Heine University in Dusseldorf, who published their findings in the journal Chest of the American College of Chest Physicians.
Prof. Lavie has published more than 340 scientific articles and eight books in the field of sleep research, including The Enchanted World of Sleep
, which is suited for the layman and translated to 15 languages. Lena, a senior researcher in the Technion, has collaborated with him on sleep research focusing on understanding the cellular and biochemical impacts of the breathing cessations.
Many sleep apnea patients go to bed at night connected to a continuous positive airway pressure (CPAP) device, which is not very comfortable but pushes through a mask pressurized air – insufficient during breathing cessation – under pressure into their lungs. This does not cure sleep apnea but can reduce the complications.
Intermittent hypoxia – the lack of adequate oxygen – initiates a cascade of events involving oxidative stress and inflammatory processes leading to atherosclerosis. But surprisingly, the new research found that in contrast to young and middle-age patients, who showed significantly higher mortality than their counterparts in the general population, elderly patients with mild or moderate apnea showed significantly lower mortality than in the general population.
The researchers suggest that the hearts of elderly sleep apnea patients get blood from a larger number of arteries – called collaterals – that develop by angiogenesis due to the lack of oxygen supply, than the hearts of patients without sleep apnea. This additional blood supply protects them if they suffer a heart attack, the Lavies write.
The Haifa researchers based their hypothesis on previous results from the Haifa group demonstrating that sleep apnea patients have in their blood high levels of a protein called vascular endothelial growth factor (VEGF). This protein is responsible for the growth of new blood vessels, and its production is triggered by a drop in blood oxygen levels.
The Technion team also showed that there are very large individual differences in the effect of hypoxia on the production of this protein. The research group found that individuals who could produce a large amount of protein when exposed to hypoxia had more blood vessels around their hearts in comparison with individuals who could not produce the protein.
Dr. Stephan Steiner and his colleagues from the cardiology department
in Heinrich Heine University reported data that provided strong support
to the Lavies’ hypothesis. Steiner and his colleagues compared the
number and size of the heart collaterals measured by catheterization in
patients with and without sleep apnea and reported that patients with
sleep apnea had significantly more collaterals than patients without
sleep apnea, even though there were no differences between the groups
in age, weight, heart condition or use of medication.
The German research in Chest
was accompanied in the same issue by an editorial that was written by
the Lavies. “If confirmed, these findings may have important clinical
implications regarding treatment of the syndrome. Moreover,” they
continued, “such findings – if combined with individual gene analysis –
may provide new treatment strategies for cardiovascular protection.”