ADD, formally known as ADHD-PI, is a subtype of ADHD characterized by inattention, procrastination, and disorganization. The main symptoms are inattention and fatigue. ADHD is an umbrella term for disorders showing impulsiveness, inattention and hyperactivity. There are three subtypes: ADHD-PI, ADHD-HI, and ADHD-C. ADHD-PI is similar to ADD, while ADHD-HI and ADHD-C involve hyperactivity. Although the subtypes differ in dominant symptoms, they can be treated effectively with the same methods like stimulant medication, antidepressants, and therapy.