What constitutes normal memory? How is memory formed and used?
Normal memory is the ability to do three major activities: 1) Learn new information; 2) Place that information into storage in the brain; and 3) When needed, retrieve that information from storage.
The two brain structures that take the lead roles in memory formation are the hippocampus and the cortex. The hippocampus registers new information and makes a memory based on this. The hippocampus also makes a decision to save information or get rid of it. If the information is saved, it goes into long-term storage, a function of the cortex. When you need it, you call it back from storage the same way you open a saved computer file. Another important part of memory is the emotional context. This is impacted by the amygdala. When a memory is embellished by an emotion, it is better remembered. Memory is helped by repeated experience of the same information. Think about studying for an exam, practicing a musical instrument, or performing a physical task repeatedly.
How is memory impacted by the normal aging process?
Starting at about the age of 40, we all begin to experience age-associated memory loss, which is a normal part of the aging process. Some common examples are forgetting where you put your keys, forgetting why you went to a certain room in your home, and when you don’t remember the name of someone you met six months ago. This is not associated with any negative effects and it has no effect on day-to-day function.
What is dementia?
Dementia is when memory loss is associated with involvement of at least one other cognitive domain, typically language. For example, not remembering a conversation you had an hour ago and having difficulty expressing yourself. Dementia affects day-to-day function. A primary symptom is repetitive questioning with rapid forgetting of new information, and/or not remembering information overnight.
Other cognitive domains may be affected by dementia in the following ways:
- Poor recognition of visual information (also known as agnosia)
- Negatively impacted procedural memory (also known as apraxia)
- Negatively impacted executive functioning
- Short-term memory loss
What are the causes of dementia?
The most common cause of dementia in people over the age of 65 is Alzheimer’s disease. Other possibilities are vascular disease affecting the brain, a family of conditions called Frontotemporal dementia, and Lewy body disease.
Do we screen for dementia?
We do not routinely screen for symptoms in people over the age of 65. The most recent recommendations from Medicare regulate that cognitive screening be a part of a wellness visit, butw there are no parameters to help providers do so. In the last few years, a group of medical students and I have developed a screening tool. We have created a web-based continuing education module for primary care physicians and it will be available by the end of the year.
The screening takes 5 minutes to complete and can be done by anyone in a medical office. It includes a three-word memory test, a clock-drawing and time-setting task, and a one-minute animal naming test. The screening is pass/fail. A person who fails is someone who needs a complete medical evaluation. Eighty percent of those who fail will have Alzheimer’s disease.
What are the benefits of screening?
A person may benefit from early diagnosis in many ways. If you get an early diagnosis, you may:
- Access medications that – though they are not curative – are helpful to treat the symptoms of Alzheimer’s disease. The earlier you start, the better these medications work.
- Exercise autonomy because as a patient you have the right to know what is going on with your mind and body.
- Tap into support and resources in the community.
- Participate in your own planning and decision-making regarding your care.
William W. Pendlebury, MD, is Medical Director of the Memory Program at The University of Vermont Medical Center and Professor Emeritus at the Larner College of Medicine at UVM. His areas of expertise include Alzheimer’s disease and related disorders, geriatric medicine and neuropathology.