Memory is one of the most important functions we possess. While not the only component of intelligence it is a very important one. It is also not just a singular function. There are several types of memory. We’ve all heard of short-term and long-term memory. There is also visual and verbal memory, immediate memory, working memory, as well as various combination of memory that endow us with certain abilities. We all know people who are good at remembering faces, directions, songs, languages, names or a number of skills.
Just as there are various types of memory there are different areas in the brain that receive, process, and store information. The key structure for memory is a small area in the temporal lobe called the hippocampus. This structure receives information and stores it for the short term. If we have to keep this information longer it is then moved to other areas of the brain. The more that a particular “byte” of information is used, the wider and more firmly it will be stored. Other factors contribute to the retention of that byte: relevance, emotional charge, linkage to other more solidly encoded information and more.
Recent research has shed light on the relationship of sleep to memory. During a stage of sleep called rapid eye movement (REM), the brain is very active and information that has recently been acquired is replayed for either storage or removal. Just as sleep is needed for memory, lack of sleep can impair memory and learning. It has been shown that there is a relationship between quality of sleep and test performance in students.
Many things besides improper sleep can cause memory impairment. Drugs and alcohol are two of the most common causes of this. Alcohol can cause amnesia during the time of intoxication and with long-term use; permanent memory loss as well as confusion can result. A number of medications such as tranquilizers, sleep aids, antihistamines and some of the older antidepressants can impair memory. The elderly are especially sensitive to the effects of medications on mental functioning.
A concussion is also a common cause of memory loss. This is defined as a loss or alteration in consciousness due to injury. If the injury is mild, memory loss is often temporary but can be permanent in more severe types of head injuries. Repeated concussions, especially if the symptoms from the first one have not completely resolved can be very serious or even fatal.
In older age groups stroke and Alzheimer’s disease account for much of the memory loss seen today. Stroke is often accompanied by other symptoms such as weakness, imbalance, and speech problems. These symptoms also come on very quickly. This is different from conditions such as Alzheimer’s disease and other types of dementia. Dementia is a loss of cognitive or thinking skills. This can be from many causes and Alzheimer’s is one cause of dementia. The early symptoms of Alzheimer’s are often very mild and affect short-term memory loss. The underlying cause of this is that the brain cells that are responsible for memory degenerate and die. We do have quite a reserve of cells but when enough of them are lost, symptoms appear. It just so happens that cells that subserve short term memory are more vulnerable than others, which is why in conditions such as Alzheimer’s disease, that function is lost early. In Alzheimer’s disease it is felt that a toxic protein called amyloid, accumulates in brain cells and eventually kills the cell. Why these amyloid proteins accumulate and how to prevent them from doing so is a topic of intense research. Many factors seem to contribute to this toxic accumulation of amyloid including hereditary, traumatic, and atherosclerotic factors, such as diabetes, hypertension, diet and smoking.
Until we find a cause and treatment for diseases such as Alzheimer’s the adage of what’s good for the body is good for the mind has some basis in scientific fact. So for now the advice of experts could be summarized as wear your seatbelt, eat your veggies, get enough sleep and try to keep active physically, mentally, and socially.
Ladies, the Women’s Health Symposium is back – Sept. 15. Register today at 375-4500. This is an opportunity to learn more about why we forget from Dr. Stuart Kieran, as well as learn about the most current women’s health tips from eight other health experts and unwind, relax and enjoy a morning for you. Visit mdmh.org for more information.
Questions or comments can be addressed to Stuart N. Kieran, MD, c/o Bitterroot Neurology, 1019 West Main Street, Hamilton, MT 59840.