Chapter 4: Memory
Among the most interesting functions of the brain are the abilities to create and store memories. It is important to understand memory before we discuss memory decline or amnesia (inability to remember), the first major category of dementia.
Many memories need to be stored in the brain only for a short time. For this reason the primary memory system is often called short-term memory or immediate memory. For example, when you have to remember a telephone number given to you by the operator, and you plan to dial that number right away and not use it again, you may repeat the number to yourself and keep it in primary memory. If you are distracted or you talk to someone before you have a chance to dial, you may forget the number.
WHAT IS MEMORY?
Memory is divided into two parts: primary memory and secondary memory. Primary memory temporarily stores information. Secondary memory stores information for a longer period of time.
Most people who are forgetful but have no serious language problems or confusion will have normal or near normal primary memory. Doctors test primary memory by seeing how many numbers someone can remember and repeat immediately. Normally, a person will be able to remember and repeat at least 5 numbers in a row.
Secondary memories are stored information that you can remember after you are distracted and some time has passed. Secondary memories may be recent (what I ate for dinner yesterday) or remote (the name of my second grade teacher).
Although people with severe progressive memory loss, such as Alzheimer's disease, have difficulty with recent memory and struggle to store new information, they often remember remote memories, even as far back as childhood.
There are many tests for secondary memory. A person may be asked the current date or the name of the President of the United States. One test for recent secondary memory is to ask a person to remember three different items-such as daisy, chair, and anger. Then the person is distracted; they are asked to add or subtract numbers. After being distracted for three minutes, the person is asked to "recall those three words. " People with normal memory will usually remember all three words after a few minutes. Anyone failing to remember at least two of these words should be evaluated by a physician.
Not all secondary memories are stored the same way. In most people words are stored on the left side of the brain. Many non-words or non-verbal items, such as faces, are stored on the right side of the brain.
In addition to being divided into the two categories of recent time and remote time, secondary memory is divided by how the material is stored: declarative memory and procedural memory.
|"How To" Memory
"what" "who" "where" "when"
Secondary Memory System
Fact Memory (Declarative Memory) >
Fact Memory, or declarative memory, stores information, facts from "what," "who," "where," and "when" kinds of questions. For example, fact memory answers questions such as "Who is the president..." People with Alzheimer's disease often have difficulty with fact (declarative) memory.
How-to Memory (Procedural Memory)
How-to Memory, or procedural memory, stores information on ways to do activities, for example, the series of actions needed to ride a bicycle or how to use a key.
Often people with severe loss of declarative memory (or fact memory) still have their procedural memory. Recent research projects have examined ways to teach people with Alzheimer's disease new behavior skills, such as how to find their own bedroom, by using procedural memory. However, in dementia, certain types of procedural memory may also fail.
AGING AND MEMORY
There are many possible reasons for occasional forgetfulness at any age. To remember someone or something, a person must first pay attention or carefully "attend" to the situation. If a person does not pay attention to an event, the details of the event will not be stored in their memory. As a result, they will not be able to remember it.
Many older people feel as if their memory does not work as well as it did when they were younger. If they lose their keys twice in one week, they fear they have developed Alzheimer's disease.
As people age, there are changes in the sensory systems, including seeing, smelling, and hearing. With sensory system changes, there may be errors in the way the body gathers information. Aids, such as eyeglasses and hearing aids, can help the person see and hear finer details.
For example, the person without the hearing aid may miss facts, such as a conversation that centers first on buying a new car, moves onto a discussion of a local bank robbery, and then onto talk about a neighbor's recovery from surgery. The next day the conversation may be remembered as the robbery of a car, whose owner landed in the hospital. What is recalled may be incomplete or confusing.
STRESS AND MEMORY
Older people often have many stressors in their lives. Stressors are events that cause tension, frustration, fatigue, or sadness. Stressors may also be pleasant events, such as a job promotion or a birthday celebration. Sometimes the stress relates to current events. Sometimes the stress may have accumulated over many years. The stress may reflect the loss of a close friend during childhood, turmoil from years of competition in a job, moving several times to different states or countries, early retirement, or health changes.
Trying to do too many things at once may result in poor concentration on any one project. That lack of concentration may result in poor memory. The person may forget what needs to be done next or may forget specific details about what has already been done. For example, in planning an anniversary celebration, the busy person may forget who was invited and send out some duplicate invitations. Or a person may forget to check receipts and may pay a bill twice. Sometimes doing one task in a quiet setting and finishing it without interruptions may help memory function.
People dealing with a great deal of stress have difficulty concentrating and may not be able to use strategies needed to store memories. For example, when they try to repeat someone's name to remember it, worries about an upcoming appointment may interfere. As a result, they will not remember the new information. When the stress lessens or the person is able to relax, memory should improve.
Memory can be considered in categories of time and type of material stored. The category of time has two types: primary memory-the temporary store of information, and secondary memory-information stored for a longer period of time.
In secondary memory, there are categories of time, recent or remote, and categories of type, declarative or procedural. Recent memory holds something that happened an hour or so ago while remote memory holds something that happened years ago.
Declarative memory refers to specific facts such as when or where an event occurs. Procedural memory, the "how to" memory, stores information, such as how to ice skate or ride a bike.
As people age, changes in the sensory system, such as seeing or hearing, may result in missed information. Gaps in what is stored lead to faulty recall. Aids such as eyeglasses or hearing devices can increase the accuracy of information stored, thereby helping memory.
Stress, whether positive stress such as a dinner party or negative stress such as overdue bills, may interfere with good memory. Relaxing and organizing one's routine can help.
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Material taken from
"Helping People with Progressive Memory Disorders: A Guide For You And Your Family, 2nd ed." (University of Florida Health Science Center). Used with permission from the authors: K. M. Heilman, MD, L. Doty, PhD, J. T. Stewart, MD, D Bowers, PhD, & L. Gonzalez-Rothi, PhD. (1999).