Cognitive testing of elderly Chinese people in Singapore: influence of education and age on normative scores

Age and Ageing, Nov, 1997 by Suresh Sahadevan, Noellyn J.L. Tan, Tahchew Tan, Shirley Tan

1. Word list memory (immediate recall) [12]: a 10-word list was presented and free recall assessed across three trials with the words being presented in a different order for each trial.

2. Word list (delayed recall): delayed memory for the 10 words in the word list (immediate recall) test was assessed 10 min after the third trial on immediate memory

3. Word list (recognition): recognition of the 10 words from the word list (immediate recall) test was tested when they were presented together with 10 distractor words.

4. Set test (animal category) [13]: this assesses language, verbal fluency and executive functioning by asking the subject to name as many animals as possible within 1 min.

5. Modified Boston naming test: 15 line drawings were chosen from the original 60 drawings in the Boston naming test [14] and were presented for subjects to name.

6. Constructional praxis [15]: visuo-spatial skills were assessed by presenting four line drawings of generic figures (a circle, intersecting rectangles, a diamond and a cube) for the subject to copy.

7. Block design: this performance subtest of the Wechsler Adult Intelligence Scale--Revised (WAIS-R) [16] measured visuo-spatial organisation by asking the subject to construct replicas of designs using red and white blocks.

8. Object assembly: in this performance subtest of the WAIS-R the subject was presented with cut-up cardboard figures of familiar objects to assemble.

The neuropsychological assessment battery was administered by a research psychologist who underwent training in interview techniques and procedures as well as familiarization with the various languages and dialects.

All the test materials and the instructions were translated into Mandarin and the two main dialects in Singapore--Hokkien and Teochew. Back-translation was performed to ensure accuracy and appropriateness in the phrasing of the items. Adaptations were made to the Chinese Mini-Mental Status, word list (immediate recall) and the modified Boston naming test so as to make them more locally suitable.

Statistical analysis

Frequencies and [chi square] tests were carried out using SPSS for Windows (Statistical Package for Social Sciences, Version 6.0, 1993). The [chi square] test was used to look at the associations between the demographic variables to establish which were independently exerting a significant effect on the test performances.

Our observational study had produced unbalanced data (different number of observations in each cell of the data table) and this precluded the use of analysis of variance (ANOVA) [17]. Therefore, to study in greater detail the relationship between the mean test scores and the various demographic variables, the type III sum of squares of the general linear model (GLM) in the SAS proprietary software (Release 6.04, 1987) was used.

Results

Subjects

From the original master list, 155 subjects met the entry criteria and gave consent to participate in the study. Their stratified distribution according to age, education and gender is shown in Table 1. Fifty-one percent were women and approximately half of the subjects had more than 6 years of education (47%). The subjects were generally spread across the three age categories: 35% aged 60-64 years, 39% aged 65-74 years and 26% aged 75-84 years. The two most common languages used for testing the subjects were English (39%) and Mandarin (41%); Hokkien and Teochew dialects were used in only 15 and 5% of cases respectively.