The Block Design Test (BDT) is a subtest of the Wechsler Adult Intelligence Scale-IV (WAIS-IV) and is a widely used prominent neuropsychological measure in assessing visual spatial ability, constructional praxis, motor skill, and problem-solving skill ability [1-4]. The BDT is considered the most sensitive of the WAIS-R subtests to observe central nervous system dysfunction [1,5] and is used particularly for evaluating changes in cognitive status between being cognitively healthy, with Mild Cognitive Impairment (MCI), or in dementia [6]. The performance is a timed measure for visuospatial constructional ability. The BDT requires performer to arrange a set of four or nine blocks with different colored sides to duplicate a maximum of fourteen patterns presented in ascending order of difficulty with time limitation. Korean version of BDT WAIS-IV was used, which contains the same stimuli and follows the same procedures as original WAIS-IV version.

The normative data for the BDT was obtained from Caucasian residing in the United State who are between 16 to 74 years old [1], with educational attainment ranging from 7 years to college or more. The BDT has been known to be highly related to the demographic factors; age, education, gender, race, occupation and cultural background [3,6-15]. Previous BDT normative data did not report gender differences [6,8,10,12,15,16]. Yet, there are consistent findings on gender effects on visuospatial neuropsychological testing, generally reporting better performance by men [17-19]. Gender effects on the BDT were also reported consistently, showing men outperforming women [7,17,20-22]. Despite consistent reports of the effects of gender on visuospatial test performance, previous BDT normative data do not incorporate gender effects.

Consideration and incorporation of gender difference when developing normative data is particularly important for the Korean adults because of different educational and/or occupational opportunities depending on gender for the aging population in South Korea. Therefore, consideration of gender effect is necessary in addition to the effects of education. Inappropriate application of normative data that dismiss the cultural factors may pose a major challenge to clinical research and clinicians. Taken together, we aim to report on the joint effects of age, education and gender demographic variable on BDT performance in non-demented aging population and to provide normative data.

The present study was conducted to examine the effect of demographic factors on the performance on the BDT and to provide normative data for middle to older aged adults in an educationally diverse population with consideration of the effects of gender, which is anticipated to better assist clinicians and researchers when making interpretation of the test performance [17,20,22,28]. The result showed age, education, and gender were independently associated with BDT performance.

In the present study, BDT performance declined with age, which is consistent with previous findings [6,7,14]. The results of age-related decline in BDT indicate that visuospatial ability declines with normal aging. Educational years were associated with better performance on the BDT and lower educational years were associated with poorer performance. Our finding is consistent with other normative studies that showed a significant association between education and BDT performance [7-10,12,13]. Moreover, men performed better than women on visuospatial tests independent of years of education. There was also significant interaction effects of gender and education on BDT (Figure 1).

The findings on age and education are consistent with those reported in other normative studies. The contribution of gender to the BDT performance found in our study, however, was unique from that of previous studies [6,8,12], given that the previous normative studies on BDT either reported non-significant gender effects or chose to not consider the effects of gender due to sample size. Korean older adults have significantly different educational attainment by gender, which is reflected in the results. This may be above and beyond the implicated underlying biological differences of gender. It has been speculated that the differences in neuropsychological performance between genders, especially in the old population, may be due to the reduced education, employment, and social engagement in women in less developed countries in the past. The present study supports the earlier studies of men having higher performance in visuospatial ability tests [3,15,20,22,29]. Notably, higher educational attainment of men might be related with intellectual activates during a lifetime, leading to the protection of aging individuals against cognitive decline possibly through increased intellectual activities as well as better economic resources to protect against dementia [6,14,30].

Gender effects shown in the current study compared to previous reports may appear to be amplified for Asians—particularly South Koreans. Previous studies suggested influence of not only gender and socio-economic factors but also ethnicity on educational attainment [30,31]. In other words, understanding of the effects of education on cognitive function of elderly living in South Korea cannot be separate from the effects of gender. Furthermore, the difference in the educational attainment levels leads to discrepant future employment prospects and access to opportunities. Such gender-based disparities are notable and reflected in this normative study. Many older women in South Korea were required to tend to household duties from a very young age to older adulthood and were often not supported to attend schools. It was considered that women’s role in life was to support men and their children. Men, on the other hand, had more opportunities to work outside, to have social roles, and be more independent [32]. Even with less or unschooling, men had greater opportunities working outside the home environment and interacting with others as a primary income earner of the family, which enabled men but not women to strengthen cognitive or literacy skills. Consequently, less educated men were able to educate themselves through exposure to diverse or stimulating environment, which was not the case for women. The effect of such disparity disappears in the age cohorts where women received equal or similar education as men, such as shown in the current normative data. The cultural or ethnic differences can be observed by the similar social experiences when the gender effect is lessened to a significant degree [8,33]. These previous studies were mostly made up of the Caucasian population. Although women may serve a similar social-economic role in society, their educational attainments were higher, leading to results have less significant differences between men and women [33].

There is a limitation that should be acknowledged. The participants who are young (between 55-64 years of age) and less educated (between 0-6 years of education) are limited in size, which is due to changes in societal and educational system in South Korea in recent decades. If possible, future studies including middle-aged adult participants with various educational levels may be helpful.

In conclusion, taking together the findings from the analyses, we developed the normative data to adjust for age, gender, education factors for BDT. By adopting the overlapping age stratification method proposed by Pauker [27], we were able to present more diverse and stable normative data of older adults with a sufficient number of participants in each normative block. This study provides demographically well-adjusted normative data for BDT score for a large diverse and rapidly growing population. Because earlier normative data for BDT were mostly based on a well-educated population, this study provides normative data for the educationally diverse sample and, therefore, offers more accurate information that will be more helpful in determining the severity of cognitive decline due to aging.