Central  South  Dakota  Medical News
The Clinical View
  by P.E. Hoffsten, M.D.
17 September 2003

WHY CAN’T I REMEMBER ANYTHING?

     When my son was 12 years old, he was so proud when I let him fill the gas tank on the car.  We took a trip and at the first stop he filled the gas tank.  At the second stop, late at night I had the duty.  When I went to put gas in the car, there was no gas cap on the tank.  My son was sleepy but when I asked him about it, he said he forgot and left it back at the previous station 300 miles before.  This is attributed to inexperience on his part but if you are 72 and make the same mistake, you are liable to get accused of being demented and having Alzheimer’s disease.

     The September issue of Scientific American is devoted to the function of the human brain.  One chapter is devoted to the fascinating topic of memory.  The authors begin by explaining that there is a difference between “short term” and “long term” memory.  “Long term” memory has to do with events recalled from the distant past.  As a person ages, these memories tend to stay intact and easily be recalled.  “Short term” memory has to do with events such as where you left your car keys or even where you parked your car.  Most people can easily remember where they parked their car today but nobody tries to remember where they parked their car a year ago.  As a person ages, short term memory is the one that becomes impaired.  I remember my grandfather at age 85 telling his 17-year-old grandson (me) that he could remember every room in the house that he grew up in. He remembered where the pictures and the furniture and the bathrooms were but he couldn’t remember what he had for breakfast today.  He told me his recall was just fine but his new memory was terrible.

     My grandfather had what is today is called “age-associated memory impairment” (AAMI). It is well known that the ability to learn peaks between age 22 and 28.  For whatever reason learning a whole new discipline such as a language or computers or rap music is much easier for the young than it is for the person that is older.  This has to do with the age-associated memory impairment.  There is intense research going on now to help individuals with AAMI but so far the drugs are only being tested in rats and fruit flies.  We are getting some really smart rats but the use in humans is still in the future.  That article in the September issue of Scientific American talks about these drugs.

     A second level of memory difficulty is called “mild-cognitive impairment” (MCI).  A person with this problem will have difficulty with their memory, but in addition, will have trouble coming to the right conclusion.  As an example, I helped care for a very dear individual who has mild cognitive impairment.  When she loses something, she comes to the conclusion that somebody stole it.  She is a very neat and proper individual.  Unfortunately, she has developed urinary incontinence and occasionally wets her bed.  When this occurs, she is very upset because someone has urinated in her bed and she can’t figure out how that happened or who it was.  When she fell and accidentally broke her hip, she simply could not understand why she couldn’t walk normally.  In spite of all the safe guards and all the warnings she repeatedly received, she still got up and tried to walk.  Unfortunately, she fell and broke the other hip.  Very frequently individuals with mild-cognitive impairment require constant nursing attention for their own protection and safety.

     The third level of memory impairment is much more severe and is called “dementia”.  The lay public refers to this as “Alzheimer’s disease”.  When a person’s mind has deteriorated to this level, both short term and long term memory are severely impaired.  But in addition, there are changes in the person’s behavior and mood.  Often the entire personality will change.  Dementia is a very severe and disabling condition requiring constant care for the person’s safety.

     Patients often ask if their failing memory means that they are going to develop Alzheimer’s disease.  This is a difficult question because not all patients that are demented have the same disease process.  When dementia starts it often first presents as short-term memory impairment and then progresses on to more problematic features.  Does this mean that all people with short-term memory problems will become demented?  The answer is that some people with short-term memory problems may become demented but by no means is this a universal marker for same.  Next week’s column will be devoted to risk factors for development of cognitive impairment and dementia.  It is now known that there are mental exercises that help maintain memory in the same way that physical exercise helps maintain strength and balance in your muscles.  This will be the topic of next week’s column.