Introduction

Attention span tasks are standardised neuropsychological tools that measure verbal and visual working memory. Forward digit span (FDS) measures verbal short-term storage capacity or the phonological loop. On the other hand, backward digit span (BDS) measures both temporary storage and capability to manipulate verbal information. Forward and backward visual memory spans (BVSs) measure similar indices for visuospatial information. These measures of visual and verbal aspects of working memory are based on the influential Baddeley model of working memory.1

Studies conducted in the past raise concerns regarding the variance in the performance on attention span tasks, particularly FDS, among different cultures or languages. The findings were attributed to articulation time involved in different languages.2 ,3 However, it has also been shown that performance on BDS is not related to language.2 ,3 Of note, these studies involved a comparison of two groups that were derived from distinct social backgrounds (eg, the USA and China, Hedden et al 2002). Furthermore, this effect has not yet been observed in patients suffering from neurodegenerative disorders. It is therefore important to address whether a common standardised norm derived from different language groups originating from one multicultural and multilingual society (eg, Singapore) will be adequate.

The purpose of this study was to address this issue by examining the performance on the FDS between Chinese-speaking and non-Chinese-speaking patients diagnosed with dementia and executive dysfunction in Singapore, …