Wheelchair use does not affect cognition. But yes, a test that was standardized on men will not be valid and reliable for the female population. Different cultures need to be taken into consideration when interpreting the results of any testing instrument. As does cognitive disabilities, language differences, religious belief, etc. All of these things can affect the results of a testing instrument, more or less, depending on what exactly is being assessed. Do tests get modified specifically for all these? Usually not. However, the clinician is obligated to take these things into consideration before the results are interpreted. Rarely is a number score the only source of reporting the results. Interpretation is a much larger factor.