Actually, this is an extremely good question. I’ve heard Michael Savage call liberalism a mental disorder. However, mental disorders have demonstrated good response to medical treatment with drugs. I’d have to suggest, then, that liberalism is a Personality Disorder as no drugs (that we know of at this time) provides any relief from this malady. The evidence is in the fact that many people who are strong advocates for liberalism are often reported in the news as seeking treatment for drug use/abuse - obviously the drugs do not have a positive benefit with respect to their liberalism.