Regarding mental health disability, one of the problems that I have faced, and I know that other people have faced, is requalification for the disability tax credit. In that requalification, one of the things I have never done is take out an RDSP, because we could not find the information on what would happen if I didn't requalify for the disability tax credit.
With the disability tax credit, it actually does very little for someone who is living in poverty, because they're all non-refundable tax credits. Unless you have someone such as a spouse, a parent, or a caregiver to whom you can transfer the medical expenditures, there is no actual benefit to the person with the disability unless they have a high enough income to be paying taxes.