The researcher is looking for data sets that link intellectual disabilities (not just mental health) and substance use treatment?
The Canadian Community Health Survey has a Healthy Aging component (C2008-2009). Specifically it has the variable CR1_01A, which asks “During the past 12 months, did you receive short-term or long-term professional assistance at home ...?”. The questionnaire further clarifies that professional assistance, means help from paid workers or volunteer organizations, which include assistance received because of physical, mental or cognitive health problems or limitations or because of aging. Furthermore it does deal with alcohol and drug abuse, specifically variables CIH_2, CIH_3, CIH_8L, which asks respondents about ways to improve their health, with options such as receiving medical treatment.