Can there be an opposite of adhd?

Depression.: 1depression.(persistent sadness, worthlessness, no hope for any thing, loss of interest which is persistent and pervasive in all aspects of life, desire for death and response to support is poor.) 2 grief 3 demoralization. Loss of meaning, hopelessness, suicidal ideation due to chronic illness, disability, bodily disfigurement, social isolation, feeling a burden.

No such malady: Adhd has core symptoms of inattention, impulsiveness and hyperactivity. The opposite symptoms would be hyper-attention, rational behavior and calm. Such a person would be called smart or genius which is desirable and not a malady.