Thursday, March 17, 2011

Early Detection Alzheimer’s in Elderly Patients

Detecting Dementia

Making the diagnosis of dementia is reasonably straightforward in the moderate and severe stages, but it can be problematic to distinguish the early stages of Alzheimer’s from “normal” ageing in elderly patients, although recent development has helped to clarify which neuropsychological tests discriminate most effectively. Most people who present with concerns about memory problems do not in fact have dementia, and it is also important to note that in specialist clinical practice professionals see an atypical group of patients. O’Connor (1994) found that only 3% of people identified in a community survey as having mild dementia had been referred to specialist services, along with 18% of those with moderate dementia and 33% of those with severe dementia.

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Early Detection

Interest in the early detection of Alzheimer’s has increased with the recent licensing of anti-cholinesterase inhibiting medication as a treatment for the cognitive impairment of early-stage Alzheimer’s. This detection on early-stage of the disease is increasingly undertaken in the context of multidisciplinary memory clinics, where neuropsychological assessment plays a critical role in establishing a diagnosis. Early detection of DAT offers the possibility of introducing psychosocial and pharmacological interventions at an early stage. It has been demonstrated that memory clinics can provide an effective focus for early intervention and for the development of integrated psychosocial approaches. Early detection of Alzheimer’s remains a challenge, however, and there are a number of barriers to early detection. People with dementia, and their families, may interpret certain memory impairment of the patients as part of normal ageing process or deny that there have been any changes, and rates of detection by general medical practitioners are low.

Distinguishing Dementia from “Normal” Ageing

The boundaries between dementia and normal forgetfulness still appear somewhat fluid, and it remains unclear how the difference between dementia and normal ageing should be conceptualized. Although many older people and their families expect to observe a decline in memory functioning, there is a great deal of variation in the general population as regards the kinds of memory changes seen as part of “normal” ageing, and the issue is compounded by cohort effects. A broad overview suggests that, although memory functioning becomes less efficient from about 67 years onwards there is no general decline in memory ability and no uniform decline across the range of different memory tasks. Memory functioning is relatively more affected in the very old, so that diagnostic criteria do not allow for a dementia diagnosis made after the age of 90. The following general observations can be made with regard to memory changes in healthy older people:
  • Working memory may be affected.
  • Episodic memory is affected to a much greater degree than semantic or procedural memory.
  • Immediate recall is affected more than delayed recall, while recognition memory is unaffected.
  • Retrieval is slower and less efficient, with more rapid and extensive forgetting.
  • Prospective memory remains as good as that of younger people if external aids and reminders can be used, but is poorer if no such aids are available.
  • Autobiographical memory does not show the stereotypical discrepancy between vivid memories of the distant past and hazy memories of more recent events; instead, memories across the lifespan show loss of detail and become vaguer.
  • Alterations in memory functioning can be offset by intelligence, expertise and use of compensatory strategies, enabling the person to cope well despite any changes.

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What is “Normal” Memory Loss?

  • Forgetting people’s names occasionally;
  • sometimes not being able to find the right word;
  • taking longer to learn new things;
  • sometimes forgetting where one has put things, like keys, for example;
  • sometimes forgetting what one has come into a room to do.

What are the Symptoms of More Serious Memory Loss?

A more serious memory problem is one that affect’s a person’s ability to carry out everyday life activities such as driving a car, shopping or managing money. Some of the signs are:
  • asking the same questions over and over;
  • getting lost in familiar places;
  • not being able to follow directions;
  • confusion over time, people and places;
  • forgetting to eat right and regularly;
  • not bathing;
  • poor judgment about safety;
  • driving problems.

Medicines That Cause Forgetfulness

Forgetfulness is common among drug and alcohol abusers, but certain medicines also list forgetfulness as one of their side effects. Due to the age-related medical conditions, elderly people are more affected by the negative side effects, caused by medications. Approximately 163,000 people in the United States are estimated to experience serious cognitive impairment either caused or worsened by drugs.

For example, a beta-blocker medication, such as Inderal, generic name propranolol, or Lopressor, generic name metoprolol, may cause short-term memory problems. Similar results have been reported in patients who use such medications which contain the active ingredient methyldopa. Additionally, many antidepressants cause memory-related problems, especially in the beginning of the treatment. The same applies to anti-anxiety medicines like lorazepam and alprazolam or sleeping pills like triazolam. Benzodiazepines that are used to treat such disorders as anxiety, restless legs and social phobias seem to cause forgetfulness. Tranquilizers that are used to treat such conditions as Tourette syndrome and irritable bowel syndrome also seem to cause forgetfulness in some patients. Some drugs aimed at reducing high levels of cholesterol have also been criticized for such side effects. Even over-the-counter medicines, such as the antihistamine diphenhydramine, have been linked to forgetfulness.

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The Boundaries between Dementia and “Normal” Ageing

As a general rule, the lower the score on cognitive tests, the more likely it is that the person has dementia. However, Storandt & Hill (1989) found that scores of patients with very mild Alzheimer’s overlapped considerably with those of both normal older people and people with mild Alzheimer’s. Furthermore, even where people do show some degree of memory impairment, progression to dementia is not inevitable.

The area of uncertainty between “normal” ageing and dementia has attracted a number of attempts to define diagnostic categories. Among the diagnostic labels suggested are age-associated memory impairment (AAMI), mild cognitive impairment, benign senescent forgetfulness, and minimal or questionable dementia. These concepts remain controversial, and practice varies regarding their use. The category of AAMI, for example, would include large numbers of older people, and it is questionable whether changes that are essentially normative should be labeled in this way.

Which Tests Are Useful in Discriminating between Dementia and Normal Ageing?

The CERAD studies suggest that the best discriminator is performance on delayed recall tasks. A 10-word list presented in three learning trials and tested after a 5–8 min delay correctly classified 94% of controls and 86% of patients with mild dementia, using a cutting score of 2 SDs below the control group mean. Performance on naming tests was found to be useful as an adjunctive measure. If patients have impairment in delayed recall and problems in naming or verbal fluency, this is a very strong indicator for dementia. Other studies have also emphasized the value of delayed recall. Tierney et al. (1996) found that problems in delayed recall and attention were the best predictors of whether people with mild memory problems would go on to develop Alzheimer’s disease.

Sources and Additional Information:
The Book of Memory Disorders by Alan D. Baddeley

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