Nervosa

Nervosa means "the psychological addiction to a behavior, belief, or habit".

An example would be Anorexia Nervosa. Anorexia being in which someone starved themself / a serious mental disorder, where people (usually females) have a strong need to lose weight. When you combined Anorexia and Nervosa it would mean the addiction to the behavior, belief, or habit, of starvation.