Why memory complaints may signal early brain changes

Have you ever forgotten where you put your keys or had trouble remembering someone’s name? For many people, these small slips are normal, but for those with a sleep condition called isolated REM sleep behavior disorder (iRBD), noticing these changes may be more important than you think. A new study published in npj Parkinson's Disease (see the full article here) reveals that people with iRBD who report memory and thinking problems—even before they show up on medical tests—might be showing the earliest signs of brain changes related to dementia or Parkinson’s disease.

What is isolated REM sleep behavior disorder (iRBD)?

REM sleep is the part of sleep when we dream. People with iRBD move or talk during their dreams, sometimes even acting them out. Doctors have learned that iRBD can be an early warning sign for diseases like Parkinson’s or dementia with Lewy bodies, both of which affect how the brain works over time (Leitner et al., 2024).

What is subjective cognitive decline (SCD)?

Subjective cognitive decline (SCD) is when someone notices their own memory or thinking is getting worse, but tests at the doctor’s office still look normal. Scientists believe that SCD can be the very first sign that something is changing in the brain, possibly even before traditional memory tests show a problem (Pike et al., 2022).

The new study: what did scientists discover?

Researchers in Germany studied 80 people with iRBD and compared them to healthy adults. They used detailed questionnaires and brain scans to see if those who noticed trouble with their memory or attention (SCD) had differences in their brains. They found that about one third of iRBD patients reported SCD. These people not only experienced more memory and attention difficulties, but also showed more signs of sadness (depressive symptoms) and performed a bit worse on thinking tests than those who didn’t notice any problems.

Most interestingly, brain scans showed that people with SCD had less grey matter (the brain’s "thinking" tissue) in a region called the left superior frontal gyrus. This area helps with attention, memory, and decision-making. The more severe their memory complaints, the smaller this brain region was. These changes are subtle, but they may signal that the brain is starting to change—possibly years before more obvious symptoms of diseases like Parkinson’s or dementia appear (Ophey et al., 2024).

Why does this matter?

Catching early signs of cognitive decline is important. If doctors and patients can spot changes before major memory loss or movement problems begin, they have a better chance to plan, try new treatments, or take part in research studies. This study suggests that simply paying attention to how you feel about your memory and thinking—especially if you have iRBD—can be a useful signal for doctors. It also highlights the value of combining patient reports with advanced health AI tools and imaging to spot changes earlier.

If you’re interested in how brain structure can actually change after medical treatment, you might enjoy reading about how brain shrinkage in a similar condition, normal pressure hydrocephalus, can sometimes be reversed after surgery (see this easy-to-read SlothMD summary).

What it means for patients and families

For people with iRBD, noticing even small changes in memory or attention could be an important clue about future health. It’s a good idea to share any concerns with your doctor, who can help decide if more testing is needed. Family members who notice changes can also help by providing extra information. Early conversations like these are key for planning ahead and protecting brain health.

Looking ahead: the future of brain health monitoring

Scientists hope that by tracking SCD and brain changes over time, they can predict who is most at risk for diseases like Parkinson’s and dementia. This could lead to earlier care and more personalized treatments. As health AI tools get better at handling sensitive health data, it’s also important to learn how to keep your personal information safe. For tips on protecting your health data, you can read this SlothMD guide on privacy in health AI.

In short, listening to your own memory and thinking concerns—especially if you have a sleep disorder like iRBD—may be more valuable than you think. It’s a small step that could help doctors catch brain changes early and support your long-term health.