You will not get the honest version in one go. Ask, let it be refused, carry on with something else, then come back to it later in the same conversation.

What the research says

A Cochrane review of behavioural and cognitive approaches, anger management among them, for outward aggression in people with intellectual disabilities found some benefit, though the evidence was of low certainty. Low certainty is worth saying out loud: these approaches look helpful and the proof is thinner than anyone would like. Slow, repeated work is a reasonable response to that rather than a sign the method is failing.

Strength of evidence: one line of research. A single study, or a theoretical account.