Lack of sleep, old age and memory loss
Study finds deep sleep brain waves linked to poorer memory retention in older people
28th January 2013 - US researchers have found that the deterioration of a specific part of the brain impairs sleep quality as people age, leading to poorer memory retention.
The study is published online in the journal Nature Neuroscience and helps explain why older people’s memories do not benefit as much from sleep as younger individuals.
Dr Simon Ridley, Head of Research at Alzheimer’s Research UK, says in a press release: "The people in this study did not have dementia, but understanding the different factors that influence our brain health as we age could be crucial in the fight against the condition."
Getting a good night’s sleep is thought to help people to remember events better.
Evidence from young adults suggests that the amount of non-rapid eye movement sleep, or slow wave sleep, correlates with the degree of memory consolidation seen whilst asleep. Adults are known to get worse at memory tasks with age and aging is connected with the deterioration of certain brain areas that are important in generating these slow waves.
36 healthy people took part in the study, half with an average age of 20 and half with an average age of 72. Matthew Walker and his colleagues from the University of California instructed them to learn a set of words and their recognition memory was tested immediately afterwards. Their sleep was then monitored overnight, with electrical scalp recordings used to measure different stages of sleep, and a second memory test was carried out the following morning. MRI scans were taken to assess the participants’ brain structure.
The researchers found that the memories of older individuals were much worse than younger ones, and the older subjects also had varying degrees of brain matter loss in the medial prefrontal cortex - a brain region involved in generating slow-wave activity during sleep.
They suggest that increasing the amount of slow-wave sleep in older people may help protect against age-related memory decline.
Dr Ridley says: "This small study makes a link between structural changes in the brain, sleep quality and memory in old age, but further investigation is needed to confirm the nature of this association.
"Increasing evidence has linked changes in sleep to memory problems and dementia, but it’s not clear whether these changes might be a cause or consequence. The people studied here were followed for a very short period, and one next step could be to investigate whether a lack of ‘slow-wave’ sleep may also be linked to a long-term decline in memory."