How & Why Dementia Impacts Memory

This video clip depicts typical memory problems in dementia (time: 4 minutes 20 seconds).

Alzheimer’s disease, and related dementias, greatly impacts one’s memory. These memory deficiencies include the inability to retain information, such as the time of an appointment, as well as memories from recent months and years. As a result of these memory deficiencies, the brain of an individual with dementia will try to compensate, filling in the gaps with false information. And memory loss doesn’t stop here; it continues to get worse as the disease progresses. As one can imagine, this process can be very trying for a loved one caring for someone with Alzheimer’s disease, particularly if it isn’t understood how dementia impacts one’s memory.

When the brain of an individual with Alzheimer’s disease is compared to the brain of someone who does not have dementia, there is a glaringly obvious difference. The brain of a normal individual remains intact, while the brain of someone with dementia is missing memory. As illustrated by the brain, one of the distinctive features of Alzheimer’s disease is the inability to remember. Frustrating as it is, the path of how one’s memory is lost generally occurs in a fairly defined and consistent manner.

One’s ability to immediately recall information is the first part of memory to go. For example, an individual with dementia might ask where it is you are going that day. You respond, “to the dentist”, the individual repeats it back, and a few minutes later, asks again. This repetition of question and answer might continue over and over, as the individual with dementia cannot store the information. In fact, this individual is not even aware that this replay of question and answer is happening.

As Alzheimer’s disease progresses, one’s memory continues to decline, and one cannot recall recent memories. Recollections of what happened that day, a month ago, several months ago, and even a couple of years ago, are lost. However, memories from 10-15 years prior and beyond are still intact. This lack of recent memory distorts a dementia patient’s reality, and their memories from many years prior become their current reality. For instance, a mother might mistake her son for her father, as she can’t comprehend how her son could possibly look as old as he does.

This distortion of time, and relationship, is very trying on families with a loved one with Alzheimer’s disease. For all intensive purposes, the relationship they previously had is lost. The dementia patient recognizes the loved one, but can’t figure out how they know the person. This is where confabulation comes in, which is the brain’s attempt to fill in gaps in memory by making up false information. For example, a person with dementia may say they walked the dog earlier. Even though this didn’t happen, the memory of what really happened is gone, and the brain is simply filling the gap. While is may appear the individual is lying, they really aren’t, as the brain really believes it to be true.

Memory continues to worsen as Alzheimer’s progresses, and memories from early childhood or memories that carry strong emotional feelings can become one’s current reality. For example, an emergency that occurred when one is young suddenly becomes a reality, and that individual is convinced they need to get to the police station. This memory can become “stuck” in one’s mind and repetitively replay. Eventually this memory will fade away, as well as all remaining memories.

This video clip depicts typical memory problems in dementia (time: 4 minutes 20 seconds).

Learn about dementia's effects on memory and the order in which they occur, includes progressive memory loss: immediate recall, recent memories, sense of time and confabulation.