COGNITIVE FUNCTIONING
OF ALZHEIMER'S DISEASE PATIENTS

Sangeeta Singg and John P. Smith, Angelo State University
David M. Freed and William W. Elder, Texas Tech University

This study examined the cognitive impairment (measured by the Folstein Mini-Mental State Exam) of 385 Alzheimer's disease patients in relation to the decline in their daily living skills (DLS) and duration of symptomatology (DS). The Dementia Informant Telephone Interview was used to categorize the patients by their DLS and DS levels. The 3 x 2 factorial analysis of variance results showed a significant main effect for DLS only. It was concluded that the decline in the cognitive skills of the Alzheimer's disease patients was related to the decline in their daily living skills, regardless of the duration of symptomatology.

Alzheimer's disease (AD) is an age-related incurable form of dementia with a prevalence that increases exponentially with age (Schneider & Small, 1996). Brannon and Feist (1997) predicted that AD and its management will become a pressing social and medical issue due to the increasing proportion of elderly population in the United States. According to a USA Weekend (DeBecker, 1997) scientific poll, 35% of American adults fear getting AD. In a recent epidemiologic study, Evans (1990) stated that if no effective treatment for AD is found and the population trends continue, the number of persons with the disease could double every 20 years.

The diagnostic criteria for Alzheimer's disease are well defined (American Psychiatric Association, 1994; Khatchaturian, 1985; McKhann et al., 1984). However, there is no known cure for AD and no effective medical treatment exists at this time (Brannon & Feist, 1997). Therefore, it is important to diagnose early so that the social and vocational embarrassment to both the patient and his or her caregiver can be prevented (Strub & Black, 1993). Currently, the most effective method of caring for the AD patients is educating the caregiver and the public about behavioral management and disease progression.

A better understanding of how a patient's cognitive status and behavioral abilities are correlated may have important implications for the management and treatment of patients with probable AD (Weiniraub, Baratz, & Mesulam, 1982). In an earlier study, Whitlatch, Zarit, and Mack (1986) demonstrated high correlations between the cognitive and behavioral abilities of AD patients. The sample size was small (N = 40). In a recent study, Logsdon and Teri (1997) found decreased cognitive functioning to be associated with reduced frequency of enjoyable activity. However, the study's main focus was depression and enjoyable activities, and again the sample size was small (N = 42).

Although the AD service providers and program planners assert that keeping the patients active and involved in their daily living tasks helps in maximizing their cognitive functioning and facilitating greater life satisfaction (Logsdon & Teri, 1997; Mace, 1987), there seems to be a lack of focus on research about the relationship between cognitive status and daily living skills of AD patients as the disease progresses. The purpose of this study was to examine the relationship among the decline in cognitive status (MMSE), the decline in daily living skills (DLS), and the duration of reported symptomatology (DS) in AD patients.

Participants

The Alzheimer's Disease Education Program directed by Dr. David M. Freed, Department of Neuropsychiatry, Texas Tech University Health Sciences Center provided evaluations as a public service to 860 volunteer participants from rural West Texas (Lubbock, Abilene, Amarillo, Brownwood, and San Angelo) and Eastern New Mexico (Hobbs). The results of these evaluations were compiled in a database located at TTUHSC.

To control for several variables, the participants diagnosed with any of the following were not included in the present study: a psychiatric disorder, another form of dementia, transient ischemic attacks, a cerebrovascular accident within the last two years, a closed head injury, a seizure disorder, untreated high blood pressure, untreated diabetes, and a history or current abuse of alcohol. This allowed for a sample of 385 participants in the present study. Of these, 44% were men and 56% were women with an average age of 73.36 years (SD = 8.85).

Instruments

The information for this study was obtained from the following materials contained in participants' files.

1. A Dementia Informant Telephone Interview (DITI). The DITI is a structured telephone interview which was designed by Freed and Elder (1996) for the Alzheimer's Disease Education Program. Each patient's primary caregiver completed this form. The DITI was used to record the participant's demographic data, dementia symptom history and duration, psychosocial history, caregiver assessment, assessment of daily living skills (DLS scale), and medical history. The DLS scale was designed to measure the abilities of the patients to perform their necessary activities of daily living. Specifically, this 4-point Likert scale measured four major areas of functioning: eating, dressing, bathing, and toileting. This scale produced a numerical value or rank for each of these four factors. The scale scores range from 4 to 16. The participants who scored between 4 to7 on the DLS scale were considered mildly impaired and those who scored between 8 to 16 were considered moderately to severely impaired in the present study.

2. The Folstein Mini-Mental State Exam (MMSE). This instrument was used to assess the cognitive status of the participants (Folstein, Folstein, & McHugh, 1975). According to Cockrell and Folstein (1988), the MMSE is a widely used instrument, which provides reliable and valid assessment of cognition of psychogeriatric patients for the clinical use and psychogeriatric research. Folstein et al. (1985) noted that although the MMSE as a single entity is unable to provide an accurate diagnosis, the accumulated research regarding its sensitivity and specificity defines its use as a screening tool. A score of 23 points or less by an individual with more than eight years of education may indicate cognitive impairment and may call for further evaluation.

Procedure

Upon approval of the request to obtain data from the files of the participants of the Alzheimer's Disease Education Program at TTUHSC, the data were provided on a diskette in a coded format to protect the patients' rights and confidentiality. The data base included the data collected over a period of five years at multiple dementia screening clinics.

The participants were obtained via newspaper advertisements, word of mouth referrals, local chapters of Alzheimer's Association, area physicians, area nursing homes, and the Area Agency on Aging offices. The informants who were mostly the family members (98%) and primary caregivers were contacted by telephone to complete the DITI. Af the conclusion of the DITI, an appointment for the participant was made to conduct the neuropsychological assessment. The participants who met the diagnostic criteria for a diagnosis of probable dementia of the Alzheimer's type specified in the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (American Psychiatric Association, 1994) were referred to their physicians for formal diagnosis and treatment.

Results

The participants' mean MMSE score was 19.52 (SD = 6.71) and mean DLS score was 5.12 (SD =1.88). Their average DS was 4.65 years (SD = 3.66). Ninety percent of the participants were classified as mildly impaired (DLS scores 4-7) in their daily living skills and 10% were classified as moderately to severely impaired (DLS scores 8-16). Forty-seven percent of the participants were reported to be experiencing symptoms of AD for a period of less than three years; 27% were in the category of three to five years; and 26% were in the category of a period over five years.

The data were analyzed by using a 3 x 2 factorial analysis of variance (ANOVA). The results showed a statistically significant difference between the mean MMSE scores for mild (M =20.13, SD = 6.42) and moderate to severe (M =13.57, SD = 6.67) levels of DLS, F (1, 379) = 26.34, p < .0001. The mean MMSE scores of participants who had DS less than three years (M = 20.71, SD = 6.54), three to five years (M = 19.06, SD = 6.19), and greater than five years (M = 17.78, SD = 7.19) did not differ significantly, F (2, 379) = 2.71, p = .07. There was no significant DLS x DS interaction with regard to the mean MMSE scores of the participants, F (2, 379) = .88, p = .42.

The participants who were mildly impaired in daily living skills showed significantly higher cognitive functioning as compared to those who were in the moderate to severe levels. Mace and Rabins (1991) had noted that there appeared to be a relationship between individuals' ability to appropriately manage their daily living tasks and their degree of neuronal deficits. This postulate is supported by the results of the present study. We agree with the suggestion by Mace and Rabins that, by maintaining the highest possible level of independent daily living skills, the AD patients' degree of cognitive abilities might be preserved for a longer time span.

The results also indicated that the duration of symptomatology was not a factor related to the decline in cognitive skills of the participants. However, the limitations of this study must be taken into account before any generalizations or cause-effect relationship assumptions are made.

One limitation of this study is the fact that it is a secondary analysis of the data relying on the subjective reporting of information and behaviors. Also, the neuropsychological assessment was performed by numerous individuals over a five-year period in multiple dementia screening clinics. Further, some extraneous variables such as gender, socioeconomic status, ethnicity, and age were not controlled. In spite of these limitations, the significant relationship between cognitive skills and daily living skills of AD patients should not be ignored.

The conclusion of this study is that the decline in the cognitive skills of the patients diagnosed with probable AD is significantly related to the decline in their daily living skills, regardless of the duration of symptomatology. This has implications for preliminary screening by the clinician who is trying to estimate the severity of dementia, based on the caregiver's report of DLS, without having to directly evaluate the patient. Based on this study and clinical observations, we hypothesize that if AD patients' DLS is maintained on an optimal level, then their cognitive functioning may also benefit. Future research needs to explore this DLS and cognitive functioning connection.

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