Sleep disorders increase stroke risk: study

Sleep disorders increase stroke risk: study

According to a research, sleep disorders may increase the risk of stroke and hinder recovery from the condition.

Study co-author Dr Dirk M. Hermann of the University Hospital Essen, Germany, and colleagues noted that previous research had suggested a link between sleep disorders and stroke risk and recovery. In order to gain a better understanding of this association, the team conducted a meta-analysis of 29 studies that assessed how sleep disorders - such as insomnia and obstructive sleep apnea (OSA) - may be associated with stroke and stroke recovery.

Dr Hermann and colleagues noted that sleep disorders could usually be categorised in one of two groups: sleep-disordered breathing (SDB) - such as OSA, where breathing repeatedly stops and starts during sleep - and sleep-wake disorders (SWD), such as insomnia, which reduces sleep duration. SDB was most severe for patients with ischemic or haemorrhagic stroke, and these disorders persisted during stroke recovery.

However, the team noted that such problems improved with treatment, such as continuous positive airway pressure (CPAP), which provides the patient with a constant flow of air through the nasal passages during sleep. Overall, the researchers concluded that the evidence to date strongly suggests that SDB increases the likelihood of stroke and, without treatment, can hamper stroke recovery.

The authors found evidence that SWDs was weaker for insomnia, restless leg syndrome, and hypersomnia - increase stroke risk and harm stroke recovery. While the study does not pinpoint the exact mechanisms by which sleep disorders may lead to stroke and hinder recovery, Dr Hermann told Medical News Today about one possible pathway.

"Sleep has important restorative functions in the brain," he explained. "Sleep enables neuronal plasticity processes, which are required for stroke recovery." Based on the evidence, the researchers believe individuals who have had a stroke should be monitored for sleep disorders.

Dr Dirk M Hermann mentioned that although sleep disorders are common after a stroke, very few stroke patients are tested for them. "The results of our review show that should change, as people with sleep disorders may be more likely to have another stroke or other negative outcomes than people without sleep problems, such as having to go to a nursing home after leaving the hospital."

While there are a number of drugs that are available for sleep disorders, the research team is cautious to recommend them for stroke patients, due to insufficient evidence of their safety in this population.

Separately, a recent study has identified a higher risk of heart disease for individuals who have hidden tooth infections.

Researchers from the University of Helsinki in Finland have uncovered a link between dental root tip infection, known as apical periodontitis, and greater risk for acute coronary syndrome (ACS) - an umbrella term for conditions that involve blocked blood flow to the coronary arteries.

Study co-author John Liljestrand of the Department of Oral and Maxillofacial Diseases at the University of Helsinki and colleagues published their findings in the Journal of Dental Research. Apical periodontitis is a condition characterised by inflammatory lesions of the pulp in the centre of the tooth, most commonly triggered by infection.

"While the condition can cause pain, this may not present until later on in the infection, meaning some people who have apical periodontitis are unaware they have it; most cases are uncovered unexpectedly through X-rays." The results revealed that patients with apical periodontitis were more likely to have CAD or ACS; this association was strongest for patients whose apical periodontitis was untreated and required a root canal, with a 2.7-times greater risk of ACS.

These results remained after accounting for a number of possible confounding factors, including patients' age, sex, smoking, type-2 diabetes, body mass index (BMI), and number of teeth.

Based on their findings, the researchers believed apical periodontitis could be considered a risk factor for heart disease. "Our findings support the hypothesis that ELs [endodontic lesions] are independently associated with CAD and in particular with ACS. This is of high interest from a public health perspective, considering the high prevalence of ELs and CAD."

Additionally, the team found that patients with apical periodontitis had higher levels of antibodies in their blood that are associated with other common bacteria, further suggesting that oral infections can affect other areas of the body.