Dementia is a condition that affects the brain in a way that makes it harder for a person to remember things, think clearly, and do everyday tasks. One of the most noticeable changes in someone with dementia is how they struggle to hold onto long-term memories. Long-term memory is the part of our brain that stores information for a long time, like remembering your childhood, important life events, or facts you learned years ago. When dementia sets in, this ability to keep and recall those memories starts to fade, and it can be very confusing and upsetting for both the person and their loved ones.
The brain is a complex organ, and different parts of it are responsible for different types of memory. The hippocampus, which is a small area deep inside the brain, plays a big role in forming and storing long-term memories. In people with dementia, especially in the most common type called Alzheimer’s disease, the hippocampus often shrinks or becomes damaged. This shrinkage means the brain has a harder time creating new memories and also retrieving old ones. Studies using brain scans have shown that as dementia progresses, the hippocampus gets smaller, and this is linked to worsening memory problems [1].
Another important factor in long-term memory loss with dementia is the way brain cells communicate with each other. Brain cells, or neurons, connect through tiny structures called synapses. These synapses allow information to pass from one cell to another, which is how memories are formed and stored. In dementia, these connections start to break down. The brain’s ability to strengthen these connections, a process called synaptic plasticity, also declines. This means that even if a memory was once strong, it becomes harder to access as the connections weaken over time [1].
Dementia also affects the white matter in the brain. White matter is made up of nerve fibers that help different parts of the brain talk to each other. When dementia damages the white matter, it slows down the speed at which information travels across the brain. This can make it harder for someone to recall memories that require pulling together information from different brain regions, like remembering a story or a sequence of events [1].
In addition to these physical changes, dementia can cause problems with how the brain handles stress and inflammation. The brain is constantly exposed to small amounts of damage from things like stress and toxins, but in a healthy brain, it can repair itself. In dementia, this repair process doesn’t work as well. There is more oxidative stress, which means harmful molecules build up and damage brain cells. There is also more inflammation, which can further harm the brain and make memory problems worse [1].
Sleep is another important factor when it comes to long-term memory and dementia. Good sleep helps the brain clear out waste products and strengthen memories. People with dementia often have trouble sleeping, and this can make their memory problems worse. When sleep is disrupted, the brain doesn’t get the chance to properly store and organize memories, so long-term memory retention suffers [1].
Lifestyle factors also play a role. Being physically active, eating a healthy diet, and staying socially engaged can help protect the brain and slow down memory loss. On the other hand, a sedentary lifestyle, poor diet, and social isolation can make dementia symptoms worse. For example, lack of exercise can reduce the levels of a protein called BDNF, which is important for keeping brain cells healthy and supporting memory [1].
Hearing loss is another factor that can affect long-term memory in people with dementia. When someone has trouble hearing, their brain has to work harder to understand sounds and words. This extra effort can take away resources from other brain functions, like memory. Studies have shown that people with hearing loss are more likely to develop dementia and have faster memory decline [2].
Some research has also looked at the impact of diet on memory and dementia. For example, there is evidence that consuming artificial sweeteners and sugar alcohols may be linked to a higher risk of cognitive decline. These substances might affect the brain in ways that make it harder to retain long-term memories, although more research is needed to fully understand this connection [4].
The way sleep duration affects long-term memory in people with dementia is still being studied. Some research suggests that both too little and too much sleep can be linked to worse memory outcomes, but the exact relationship is not yet clear. What is known is that getting good quality sleep is important for memory, and people with dementia often struggle with sleep problems [5].
It’s also important to understand the difference between normal forgetfulness and the memory loss seen in dementia. Everyone forgets things sometimes, like where they put their keys or the name of someone they just met. This is a normal part of aging and doesn’t usually affect a person’s ability to live independently. In dementia, memory loss is more severe and affects a person’s ability to solve problems, communicate, and make decisions. This kind of memory loss can make it hard for someone to manage daily tasks and can lead to confusion and frustration [3].
As dementia progresses, the ability to retain and recall long-term memories continues to decline. Early on, a person might forget recent events or have trouble learning new information. Over time, they may start to forget older memories, like names of family members or important life events. This can be very distressing for both the person with dementia and their loved ones.
There are many factors that can influence how dementia affects long-term memory retention. Brain structure changes, problems with brain cell communication, sleep issues, lifestyle factors, hearing loss, and diet all play a role. Understanding these factors can help people take steps to protect their memory and slow down the progression of dementia.
Sources
[1] Natural Remedies Human Health – Top Reasons for Memory Loss and How to Prevent It
[2] JAMA Network Open – Hearing Loss, Brain Structure, Cognition, and Dementia Risk
[3] Nuvance Health – Memory, normal forgetfulness vs. dementia and when to see a doctor
[4] Neurology – and No-Calorie Artificial Sweeteners and Cognitive Decline
[5] Nature Scientific Reports – U shaped association between sleep duration and long term cognitive trajectories
