Memory loss and the dementia diagnosis

Memory loss related to recent memory (secondary memory) is frequently referred to as short-term memory loss. The anatomic site of dysfunction for immediate memory is believed to be the limbic system. Individuals with a lesion in this area may have little difficulty repeating digits immediately, but experience memory loss related to a rapid decay of these memories. Sometimes, within minutes, an individual with a lesion in the limbic system may be totally unable to recall the digits or even that the test has even been administered. Thus, immediate memory involves memory loss or inability to recall information that was previously registered by the primary memory. Clinically, to test recent memory, an individual may be asked to remember three objects by an examiner. They will then be distracted for three to five minutes and will then be asked to recall the previously registered three objects. Sometimes, the examiner may give a demented individual a clue (such as “one of the objects you missed was a color”) and the individual will then correctly identify the object. If this occurs, memory testing should be scored as “three out of three with a clue" which is considered to be a slight impairment. Giving clues to an individual with memory loss associated with their immediate recall is pointless, because the information has not been registered in the first place. Wernicke-Kosakoff syndrome is an example of a condition in which immediate recall may be intact, while recent memory has been impaired.

Memory loss related to remote (tertiary) memory:

Memory loss associated with long-term memory or what may be referred to as remote memory, is usually associated with memories from the past. Remote or long-term memory capacity is believed to be relatively unlimited, with such memories believed to be permanently retained. Accessed tertiary memories are slow and the anatomical dysfunction and long-term memory dysfunction is to believed to be in the association cortex. In the early stages of dementia, long-term memories or remote memories usually remain intact. This type of memory loss is usually tested by instructing the individual to remember personal information or material from the past. An important factor that may influence an individual's ability to remember may be whether the memory had some personal significance. An example may be that a woman who worked as a seamstress may remember many details related to her occupation, but not recall the names of the past three presidents, or some of the major cities in the United States. Thus, an individual's memory loss of significant past information is an ominous finding. Collateral data from informants such as family members is essential in the proper assessment of memory functioning. In summary, problems with immediate and short-term memories are frequently impaired in individuals with dementia, while long-term or remote memories are often spared until much later in the course of the disease.

Some information from DSM-IV-TR Mental Disorders: Diagnosis, Etiology & Treatment by Michael B. First and Allan Tasman

Additional information and webpage By Paul Susic MA Licensed Psychologist Ph.D. Candidate