‘Mental illness’ means a clinically significant disorder of thought, mood, perception, orientation, memory or behavior which seriously limits the capacity of a person to function in the primary aspects of daily living, including, without limitation, personal relations, living arrangements, employment and recreation. The term does not include other mental disorders that result in diminished capacity, including, without limitation, epilepsy, intellectual disability, dementia, delirium, brief periods of intoxication caused by alcohol or other substances or dependence upon or addiction to alcohol or other substances.