Sunday, January 3, 2010

Neuropsychological Testing for Alzheimer’s

Standard psychological/psychiatric evaluation, if there is even slight suspicion on the Alzheimer’s disease, should be complemented by additional neuropsychological tests, conducted to determine more specifically the type and level of cognitive impairment people are exhibiting, as well as their strengths and preserved abilities. Information about preserved abilities is important to help form a treatment plan and recommendations about environmental modifications that would be useful (e.g., job modifications, looking for a more supportive living environment, etc.).

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Neuropsychological testing is used in the evaluation of Alzheimer's disease to learn more about the nature and level of a person's impairment. The testing is often conducted by a neuropsychologist (a psychologist who specializes in the relationship between the brain, behavior, and functioning). Several tests are available that can narrow the range of possible diagnoses by producing test patterns that resemble Alzheimer's or other conditions. A neuropsychologist might use one test or a whole battery of them, depending on the individual.

Neuropsychological tests measure memory, concentration, visual-spatial, problem solving, counting, emotional states and language skills and the "scores" on these tests contribute to a ratings scale which is used as evidence to support a diagnoses. When considering rating scales in general and dementia in particular, it is important to keep the following items in mind:

  1. A rating scale is only as good as the clinician using it. This means that rating scales are subject to "operator error" and need to be viewed in the context of the "complete" package of evidence.
  2. Rating scales do not confirm a diagnosis. This means that they are used to assess and monitor suspected or diagnosed cognitive problems. They are part of the evaluation and management of dementia based disease, but are not "diagnostic tools" unto themselves.
  3. Rating scales do not exist in a vacuum. This means that they need to be viewed in the context of the applicant’s entire medical history and clinical findings. While the results can form a piece of the puzzle, they by no means represent the entire puzzle.
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A variety of tests are available that can narrow the range of possible diagnoses by identifying patterns indicative of Alzheimer's, head injury, stroke, or other conditions. For example, someone with a head injury may exhibit amnesia (an inability to learn and recall new information and/or problems remembering previously learned information or past events) as the most prominent symptom, while someone with Alzheimer's will show short-term memory impairment, but not necessarily amnesia. A neuropsychologist might administer one test or a whole battery of them, depending on the individual.
Some of the more common tests include:

-        Neuropsychiatric Inventory (NPI)

The Neuropsychiatric Inventory (NPI) evaluates a wider range of psychopathology than comparable instruments (Cummings et al, 1994). Assesses 12 neuropsychiatric disturbances common in dementia: Delusions, hallucinations, agitation, dysphoria, anxiety, apathy, irritability, euphoria, disinhibition, aberrant motor behavior, night-time behavior disturbances, and eating disturbances. It is scored from 1 to 144 and severity and frequency are independently assessed. The NPI has been translated into a number of languages and it is now used widely in drug trials.

-        Clock drawing test

The clock drawing test takes only 2 minutes to administer and assesses cognitive or visuospatial impairment (Brodaty & Moore, 1997; Shulman et al, 1986). The main advantages are its simplicity of administration and the non-threatening nature of the task. The patient is asked to draw a clock face marking the hours and then draw the hands to indicate a particular time (e.g. 10 minutes to 2).

-        ADAS-Cog (Alzheimer's Disease Assessment Scale-Cognitive)

An 11-part test that takes 30 minutes to complete and is considered more thorough than the Mini-Mental State Exam. The ADAS-Cog focuses on attention, language, orientation, executive, and memory skills.

-        Blessed Test

One of the older neuropsychological tests, the Blessed Test takes only 10 minutes and assesses memory, attention, concentration, and the ability to complete activities of daily living, such as bathing, dressing, grooming, and eating.

-        CANTAB (Cambridge Neuropsychological Test Automated Battery)

This unique tool includes 13 interrelated computerized tests of memory, attention, and executive functioning. The battery is administered through a computer by using a touch-sensitive screen. Research has shown the CANTAB to be relatively unbiased regarding a person's language and culture. It's also been shown to be quite sensitive to warning signs of Alzheimer's disease.

-        Cognistat (Neurobehavioral Cognitive Status Examination)

The Cognistat assesses language, construction (the ability to copy or assemble items in a two- or three-dimensional space), memory, mathematical calculations, and reasoning/judgment. The test takes approximately 10 minutes when the person shows no cognitive impairment; for those who are cognitively impaired, the test can take 20 to 30 minutes.

-        Behavioral Pathology in Alzheimer's Disease Rating Scale (BEHAVE-AD)

This test provides a global rating of behavioral symptoms such as verbal aggression, physical aggression, and hyperactivity. In addition to diagnosis, the scale is often used when clinicians want to determine how well medications are working to manage someone's behavioral symptoms.

-        Dementia Rating Scale - 2 (DRS-2)

This is a 15-20 minute measure of cognitive impairment, which yields scores in five areas: attention, initiation/perseveration (i.e., the ability to start or stop doing a task), construction, conceptualization (interpreting what is seen, heard, etc., into an idea or a conclusion), and memory.

Obviously, diagnosing Alzheimer's is a complex process because the physician (or team of health care professionals) has a great deal of information to sort through. Most of the cognitive tests that have been used to decide whether someone has Alzheimer's disease or vascular dementia have not been very helpful when used alone. A new report published by the American Psychological Association concluded that when older people are confused and forgetful, doctors should base their diagnoses on many different types of information, including medical history and brain imaging.

Sources and Additional Information:

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