NADD Bulletin Volume IV Number 5 Article 2

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Neuropsychological Evaluation as a Tool for Assisting with Diagnosis of Dementia in Persons with Mental Retardation

Glen A. Palmer, Ph.D.

Abstract

There has been significant interest in the diagnosis and treatment of dementia in persons with developmental disabilities within the last decade. However, little has been written regarding the use of neuropsychological evaluation as a diagnostic tool to assist in this process. One likely reason is that many tests commonly used for the assessment of dementia are inadequate for persons with mental retardation due to lack of test specificity. This paper introduces a short battery of tests that has been useful in working for persons with mental retardation. A brief description of neuropsychological evaluation is presented. Qualitative differences in test performance between individuals with and without dementia of the Alzheimer type are discussed. Two case studies are presented for comparison to demonstrate the benefits of neuropsychological evaluation. Current limitations of evaluation with this population and research recommendations are presented.

Introduction

Individuals with mental retardation are living longer due to recent medical advances and improved quality of life. As the population of older persons with mental retardation increases, so will the number of individuals who will develop Alzheimer disease or other forms of dementia. Within the last few years, publications have been developed to assist with diagnosis (Aylward, Burt, Thorpe, Lai, & Dalton, 1995), and treatment (Janicki, Heller, Seltzer, & Hogg, 1995) of dementia (particularly Alzheimer disease) in persons with mental retardation.

According to the American Psychiatric Association (2000), dementia involves multiple cognitive deficits that include memory impairment. Cognitive disturbances including agnosia (failure to recognize or identify objects despite intact sensory function), apraxia (impaired ability to carry out motor activities despite intact motor function), aphasia (language disturbance), and executive functions (person’s ability to organize, plan, and carry out activities) may be present. A gradual onset and continuing cognitive decline characterize dementia of the Alzheimer type. Vascular dementia is characterized by a stepwise regression. Focal signs/symptoms are usually reported, or presence of cerebrovascular disease is noted. Assessment of memory alone is not sufficient for evaluation of dementia. A battery of tests including free memory recall, learning, recognition memory, verbal fluency (i.e., generative naming), confrontation naming, and praxis have been found helpful for staging dementia severity or tracking its progression (Kaszniak, Wilson, Fox, and Stebbins, 1986; Welsh, Butters, Hughes, Mohs, and Heyman, 1992).

Several domains are assessed in a neuropsychological evaluation including intellectual functioning, sensorimotor abilities, attention, language, memory, executive functions, and personality factors. Both quantitative and qualitative aspects of test performance are observed. Quantitative measures allow the clinician to compare and individual’s performance to a normative sample. Qualitative measures focus on the processes that individuals use to perform the battery of tests. For a review of current neuropsychological methods, the reader is referred to Grant and Adams’ (1996) text on neuropsychological assessment.

In this study, two cases are presented for comparison with respect to a short battery of neuropsychological tests.

Method

Participants

Two individuals with mental retardation and Down syndrome were referred for neuropsychological evaluation. The first individual (Case 1) was a 49-year-old Caucasian female with mild mental retardation (WAIS-III FSIQ = 57) who was recently diagnosed with Alzheimer dementia. Staff subjectively reported decrease in abilities to carry out activities of daily living, and decrease in work pace. Increased agitation and frequent changes in mood were noted. Frequent incontinence was also recently reported.

The second individual (Case 2) was a 52-year-old female patient with mild mental retardation (WAIS-III FSIQ = 65) who was referred due to increased withdrawal, sadness, and subjective report of decreased ability to conduct activities of daily living. The referring agency was concerned about symptoms of depression and possible dementia. She recently experienced the loss of two different family members. An increase in crying, tantruming, and withdrawal from activities of daily living were reported.

Procedures

Both participants were administered a short battery of tests to assess areas of memory, language (i.e., confrontation naming and semantic fluency), visual attention, and executive functions (e.g., mental flexibility). Sensorimotor skills were comparable for each individual. Each individual had some difficulties with imitating hand movements, but simple motor skills were intact. Sensory discrimination was intact, and no sensory suppressions were noted.

Instruments

The following tests (in addition to IQ scores from intelligence testing) were selected for comparison:

•Fuld Object-Memory Evaluation (Fuld, 1977)

•Animal Naming Test (Spreen & Strauss, 1998)

•Boston Naming Test (Kaplan, Goodglass,

& Weintraub, 1983)

•Early Signs of Dementia Checklist

(Visser et al., 1997)

•Color Trails Test (D’Elia, Satz, Uchiyama, & White, 1996)

Results

Both participants were cooperative with the testing procedures and appeared adequately motivated. Therefore, the test results were considered to be an accurate appraisal of each person’s abilities. Table 1 provides a summary of raw scores for each participant.

On the Fuld Object-Memory Evaluation (Fuld, 1977), the first participant (Case 1) demonstrated much difficulty remembering 10 objects on immediate recall (FULD 1). After each recall trial, the patient was reminded which of ten items she had missed. The patient could not recall any more items on trial five (FULD 5) than on trial 1. This demonstrated that the patient had significant difficulties with learning new information. Selective reminding did not assist with facilitating memory recall, as demonstrated by the high number of ineffective reminders (IR). After five minutes, the individual was asked to recall the 10 items. She could not recall any of the items, and a multiple-choice format was given to assist with facilitating recall. The patient recalled 5 items (See Retention Estimate). However, 4 of the five items were the last item of the multiple-choice format.

The second participant (Case 2) recalled 5 items on immediate recall of the first trial. By the fifth trial she recalled a total of 8 items, and selective reminding task was effective (i.e., low IR score). After five minutes, the patient was asked to recall the 10 items. She named 8 items on free recall, and identified all 10 items on cued recall.

Generative naming tasks in response to semantic cues were administered. In case 1, the patient could recall between 1 and 3 items for each condition (i.e., FULD NAMES, FULD FOODS, FULD HAPPY, FULD VEGETABLES, FULD SAD, and ANIMALS). In case 2, the participant identified between 5 and 12 items.

Confrontation Naming (Boston Naming Test; Kaplan, Goodglass, and Weintraub, 1983) was quite difficult for both individuals. The first participant correctly identified 12 of 60 items. However, she was unable to identify some rather simple items presented early in the test (i.e., could not remember the name of a tree or flower). The second participant identified 27 of 60 items.

On the Early Signs of Dementia Checklist (Visser, et al., 1997), both participants were above the cutoff score of 14. According to Visser, scores above 14 are indicative of signs of mental deterioration. A high score in and of itself does not confirm diagnosis of dementia.

On tasks of visual tracking and mental flexibility (Color Trails A and B; D’Elia, Satz, Uchiyama, and White, 1996), Case 1 could not complete either task. Testing was therefore discontinued. For Case 2, the patient completed both tasks in times that were commensurate with her intellectual functioning level.

Discussion

In this particular presentation, deficits in memory, confrontation naming, generative naming in response to semantic cues, visual tracking, and mental flexibility were noted in Case 1. Deficits in these domains are consistent with performance on neuropsychological tests in the normal population for persons with Alzheimer disease. With respect to memory performance, the patient exhibited problems with memory storage and learning of new information. Cues did not assist with facilitating recall.

In contrast, the second participant performed better on tasks of memory, confrontation naming, generative naming in response to semantic cues, visual tracking, and mental flexibility. Her performance was consistent with individuals who do not have diagnosis of dementia of the Alzheimer type. However, she did exhibit symptoms of depression. The patient was placed on antidepressant medication and was reportedly doing well (e.g., decreased withdrawal and increased performance with activities of daily living).

There are limitations to the current study. First, the study only compared qualitative differences in responding to a short battery of tests. A “normative” database for persons with mild, moderate, severe, and profound retardation would be beneficial on neuropsychological tests targeted specifically for this under-served population. This database would assist with addressing the problem of floor effects on many psychological tests.

A wealth of literature exists pertaining to differential diagnosis of these disorders in the normal population (e.g., dementia of the Alzheimer type versus vascular dementia or depression). Identifying neuropsychological profiles for differentiating types of dementia in this under-served population will be extremely valuable.

References

American Psychiatric Association. (2000). Diagnostic and statistical manual of mental disorders (4th ed.-text revision). Washington, DC: Author.

Aylward, E. H., Burt, D. B., Thorpe, L. U., Lai, F., & Dalton, R. J. (1995). Diagnosis of dementia in individuals with intellectual disability. Report for the Working Group for the Establishment of Criteria for the Diagnosis of Dementia in Individuals with Intellectual Disability. Washington, DC: American Association on Mental Retardation.

D’Elia, L. F., Satz, P., Uchiyama, C. L., & White, T. (1996). Color Trails Test professional manual. Odessa, Florida: Psychological Assessment Resources.

Fuld, P. A. (1977). Fuld Object-Memory Evaluation instruction manual. Wood Dale, Illinois: Stoelting.

Grant, I. & Adams, K. (Eds.). (1996). Neuropsychological assessment of neuropsychiatric disorders (2nd ed.). New York: Oxford University Press.

Janicki, M. P., Heller, T., Seltzer, G. B., & Hogg, J. (1995). Practice guidelines for the clinical assessment and care management of Alzheimer and other dementias among adults with mental retardation. Report of the AAMR-IASSID Workgroup on Practice Guidelines for Care Management of Alzheimer Disease Among Adults with Mental Retardation. Washington, DC: American Association on Mental Retardation.

Kaplan, E. H., Goodglass, H., & Weintraub, S. (1983). The Boston Naming Test. Philadelphia: Lea & Febiger.

Kaszniak, A. W., Wilson, R. S., Fox, J. H., & Stebbins, G. T. (1986). Cognitive assessment in Alzheimer’s disease: Cross sectional and longitudinal perspectives. Canadian Journal of Neurological Sciences, 13, 420-423.

 Spreen, O. & Strauss, E. (1998). A compendium of neuropsychological tests (2nd ed.). New York: Oxford University Press.

Visser, F. E., Aldenkamp, A. P., van Huffelen, A. C., Kuilman, M., Overweg, J., & van Wijk, J. (1997). Prospective study on the prevalence of Alzheimer-type dementia in institutionalized individuals with Down syndrome. American Journal on Mental Retardation, 101, 400-412.

Welsh, K., Butters, N., Hughes, J., Mohs, R., & Heyman, A. (1992). Detection and staging of dementia in Alzheimer’s disease: Use of the neuropsychological measures developed for the Consortium to Establish a registry for Alzheimer’s Disease. Archives of Neurology, 49, 448-452.

For further information:

Glen A. Palmer, Ph.D.
Lanning Center for Behavioral Services,
Mary Lanning Memorial Hospital
Hastings, NE
E-mail: gpalmer@navix.net

(This material was included in a poster presentation at the 125th annual AAMR meeting in Denver, Colorado, in 2001.)