Older people may forget things more often because they lose their rhythm at night, a study says.
When seniors go into deep sleep, they have less coordination between two brain waves that are vital in saving new memories, NPR reports.
Matt Walker, one of the study authors and professor of neuroscience and psychology at the University of California, Berkeley, said,
It’s like a drummer that’s perhaps just one beat off the rhythm. The aging brain just doesn’t seem to be able to synchronize its brain waves effectively.
This finding seems to answer a long-standing question regarding how aging affects memory in people who don’t present with Alzheimer’s or other similar degenerative cognitive disorders.
Julie Seibt, a lecturer in sleep and plasticity at the University of Surrey in the United Kingdom, said, “This is the first paper that actually found a cellular mechanism that might be affected during aging and therefore be responsible for a lack of memory consolidation during sleep.” Seibt was not involved in the study.
However, the researchers will have to show that memory problems can be caused in a younger brain by interrupting these rhythms, Seibt added.
This study was the result of researchers trying to understand how the sleeping brain turns short-term memories into long-term ones, said Walker, who has also written the book, Why We Sleep. “What is it about sleep that seems to perform this elegant trick of cementing new facts into the neural architecture of the brain?” he asked.
Walker and a team of scientists recruited 20 young adults to learn 120 pairs of words. “Then we put electrodes on their head and we had them sleep,” Walker said. The electrodes allowed the researchers to monitor electrical waves the brain produced during sleep, focusing on the interaction between slow waves and faster waves called spindles.
When they woke up the next morning, the participants took a test to determine how many word pairs they remembered. Their performance turned out to be determined by how well the slow waves and spindles had synchronized in their deep sleep.
The experiment was repeated with 32 people in their 60s and 70s, and the brain waves were less synchronized, resulting in fewer word pairs remembered next morning.
Walker has ideas on how he can synchronize these brain waves to improve memory. “What we’re going to try and do is act like a metronome and in doing so see if we can actually salvage aspects of learning and memory in older adults and those with dementia,” he said.
The study was published in the journal Neuron.