The businessman provoked anger from mental health campaigners over comments he made as a keynote speaker at a technology conference.
During his speech, he said: "I wonder what would happen if you had an answerphone system for a psychiatric hotline. What would it sound like? 'Hello, welcome to the psychiatric hotline. If you are obsessive compulsive, press 1 repeatedly. If you are codependent, ask someone else to press 2. If you have multiple personalities, press 3, 4, 5 and 6. If you are paranoid delusional, we know who you are and what you want; stay on the line and we'll trace your call. If you are schizophrenic, listen carefully and a little voice will tell you which buttons to press.'"
Sir Brian's spokesman claimed the comments were taken out of context.
He said: "He wasn't poking fun in any way. Most families have someone with some kind of problem so he wouldn't do that.
"His Souter Foundation has donated over many years to research and help for people who have mental disabilities in any way or who are fragile. He's very aware of the situation and very respectful.
"It's simply that a few flippant remarks have been taken out of context from the overall speech. If he has upset anyone then he would very much like to apologise."
Following Sir Brian's comments, Judith Robertson, director of mental health campaign See Me, said they were "hurtful and stigmatising".
Norman Lamb MP, minister for care and support at Westminster, also said he was appalled.
However, Marjorie Wallace, chief executive of the mental health charity Sane, said: "The day we stop being able to have any humour about the subject of mental illness is the day that stigma has won."