Yes this is my first H&C application for my parents.
Factors :-
1. They are aged and have no siblings/parents back home, all immediate relatives are in Canada, United States and Scotland.
2. Their elder son (my brother) is a patient of Schizophrenia and is dependent on his father for which got a recommendation letter from his doctor in a Civic Hospital. (My brother is a Canadian Permanent Resident)
3. My father is a social worker and always contribute more than 1000 Volunteer hours every year in Canada for different organizations.
4. My father is on Work Permit and contributing to Canadian Economy.
5. Some other factors like investment in Canada so far and proposed investment plan.
If your brother is fully dependent on your parents your parents have a better chance than other parents but if they are older then they will not be able to care for your brother and financially support him longterm. It also appears that you only immigrated in 2020 so your parents must have had a plan for living in their home country if you only recently immigrated knowing there was no guarantee they could move to Canada/abroad. Their application likely depends on your brother’s health/medical history, their longterm ability to care for him if necessary and their ability to support themselves while in a Canada.