Table 3 Recommendations for future studies of adults with DS and for the DS research community

Recommendations for individual studies of adults with DS

 1. The use of raw scores for certain IQ tests, particularly the K-BIT2, can minimise floor effects and may therefore be particularly useful in longitudinal studies to track change in cognitive ability over time.

 2. Non-verbal/performance IQ tests may be useful in multi-site international studies involving populations speaking different languages.

 3. The use of more common IQ tests (e.g. KBIT, BPVS, WISC-R, RCPM) and AB tests (e.g. VABS, VABS-II, ABS, ABAS) should be encouraged more broadly in both research and clinical settings. Practical implications of this are extremely valuable for detecting changes in ability.

 4. Studies may benefit from the use of both IQ and AB scales, particularly if participants include individuals with a broad range of abilities.

Recommendations for the DS research community

 1. The development of reporting standards would increase the ability of different study findings to be compared, for example reporting both raw and standardised scores, full floor effects, and separately reported results for individual DS subpopulations.

 2. Sharing of data from published studies would allow comprehensive comparison between different IQ tests and between different AB tests, in addition to correlations between these two measures for different DS subpopulations.