Heavy snorers and people with sleep apnoea may be more likely to develop memory and thinking problems at younger ages than their well-rested peers, a new study suggests.
Treatment with CPAP may delay mental decline
The good news from the study is that treating sleep apnoea with a continuous positive airway pressure (CPAP) machine may delay mental decline.
"Treatment may not cure the disease, but may delay the onset of memory problems," said lead researcher Dr. Ricardo Osorio, a research assistant professor of psychiatry at New York University's Centre for Cognitive Neurology.
Osorio cautioned that this study showed only an association between sleep disruption and developing mild mental impairment or Alzheimer's early. It didn't prove that sleep apnoea or snoring caused the mental decline. And, obviously, not everyone with sleep breathing problems will develop a brain disorder.
Read: What are sleep disorders?
"There is a question whether sleep disruption is an early symptom or a risk factor," he said.
He added, however, that the onset of mild mental decline among those treated with CPAP occurred about a decade later than those whose sleep problems weren't treated.
"That's a big gap," Osorio said. "Our assumption is that a [sleep breathing problem] works both ways – it is an early symptom and can be a risk factor," he said.
Sleep apnoea and heavy snoring are common in seniors, affecting about 53 percent of men and 26 percent of women, according to background information in the study.
Potential risk factor for Alzheimer's
"Sleep apnoea is underdiagnosed in the elderly and unrecognized as a potential risk factor for Alzheimer's disease," Osorio said.
For the study, Osorio's team reviewed the medical records of almost 2,500 people. They were between 55 and 90 years old. The researchers classified people one of three ways: free of memory and thinking problems, in the early stages of mild mental impairment, or with Alzheimer's disease.
The researchers compared people with untreated sleep breathing problems to those without sleep breathing problems. They also compared people who had untreated sleep breathing problems to those who received treatment with CPAP during sleep.
Read: Treating sleep disorders
Osorio and his colleagues found that people with sleep disruptions were diagnosed with mild mental impairment about 10 years or more sooner than those who didn't have sleep issues.
For example, heavy snorers and those with sleep apnoea who developed mild mental impairment developed the problem when they were around 77, while those without sleep breathing problems didn't develop mental problems until they were around 90, Osorio said.
Among people who developed Alzheimer's disease, those with sleep breathing problems developed it when they were about 83, compared with age 88 for those without sleep breathing problems, he said.
Developed about 10 years later
However, people with sleep apnoea treated with CPAP who developed mild mental impairment developed it about 10 years later than those whose night-time breathing problems weren't treated – 82 years versus 72 years.
The report was published online in the journal Neurology.
Dr. Sam Gandy, director of the Centre for Cognitive Health at Mount Sinai Hospital in New York City, called the study "extremely important because this is an intervention – CPAP – that can be readily prescribed and may delay onset of mental decline".
Read: Symptoms of sleep disorders
Gandy thinks a simpler way of diagnosing sleep apnoea might be needed.
"The current screening process is somewhat cumbersome and inconvenient, but that may well be offset by the benefit of enjoying more years of intact mental ability," he said.
Good sleep key to good sex
Night owls run higher risk of health problems
6 bizarre sleep disorders
Image: Stop snoring from Shutterstock