I am looking for a short measure of cognitive reserve to include in my research on  vascular cognitive impairment and reaction time and attention.

I have found the cognitive reserve index questionnaire which is tested on older and younger healthy adults, and briefly suggests it can be used by relatives for people who have dementia. Is this a good valid measure? I am not sure everyone who will come to my study will bring a relative, and also if the cognitive impairment is mild if they could answer for themselves.

Can anyone suggest other validated questionnaires I could use in its place?