Cognitive Decline in Patients with Alzheimer’s Disease: A Six-Year Longitudinal Study of Mini-Mental State Examination Scores

Cognitive Decline in Patients with Alzheimer’s Disease: A Six-Year Longitudinal Study of Mini-Mental State Examination Scores

Hikaru Nakamura (Department of Welfare System and Health Science, Okayama Prefectural University, Japan)
DOI: 10.4018/978-1-60960-559-9.ch013

Abstract

The author of this chapter present six years of longitudinal data on Mini-Mental State Examination (MMSE) scores in Japanese patients with Alzheimer’s disease (AD). Fifty-eight subjects were treated with donepezil, and nineteen served as controls. The MMSE scores recorded at the first medical examination and at the one-, three- and six-year follow-up examinations were analyzed. Over six years, the mean MMSE scores fell from 21.9 to 15.0 in the medication group and from 21.6 to 10.2 in the control group. The difference in the rate of decline between the two groups was significant. In the medication group, subjects’ sex, age and severity of cognitive impairment at entry did not affect the rate of MMSE score decline. Thirty-two patients in the medication group remained residents during the six-year period (resident group), twenty-one began as residents but were subsequently institutionalized, and five were institutionalized from the outset. The rate of decline in MMSE scores was significantly smaller in the resident group than in the other two groups. These data suggest that donepezil contributes to long-term maintenance of cognitive ability in AD patients and that a residential community setting, which is rich in stimuli, suppresses cognitive decline.
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Methods

Subjects

The subjects were patients examined as outpatients at a general hospital in Okayama between 1999 and 2008. The inclusion criteria included the following: (1) a diagnosis of dementia of the Alzheimer's type according to DSM-IV criteria, early in their course of treatment; (2) the availability of more than six years of follow-up data. Patients were excluded if they had other obvious neurological or psychiatric diseases such as cerebrovascular disease or major depression. Seventy-seven patients fulfilled the above criteria.

Procedure

The MMSE scores recorded at the first medical examination (T0) and at the one-year (T1), three-year (T2), and six-year (T3) follow-up examinations were analyzed retrospectively. A two-way analysis of variance (ANOVA) was conducted to test whether time (T0-T3), medication, sex, age at T0, severity of cognitive impairment at T0, or residential state affected the MMSE scores.

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Results

Medication

Fifty-eight of the subjects (19 men and 39 women; mean age, 75.5 years) were continuously treated with donepezil, whereas nineteen (4 men and 15 women; mean age, 80.6 years) were not. The most frequent reason for non-medication was gastrointestinal side effects. Table 1 shows the patients' MMSE scores. In the medication group, the mean MMSE score fell 6.9 points during the six-year period (annual rate of decline was 1.2). In the non-medication (control) group, the corresponding value was 11.4 points (annual rate of decline was 1.9). An ANOVA revealed significant main effects for both time and medication. The interaction between time and medication was also significant, indicating that the medication group exhibited a slower rate of decline.

Table 1.
Means and SDs of MMSE scores in the subjects
             GroupTest Period
T0T1T2T3
MSDMSDMSDMSD
Medication
Non-medication
21.9
21.6
5.2
4.6
21.8
18.2
5.3
4.8
18.1
16.7
6.5
5.6
15.0
10.2
8.0
7.0

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