- Mild – IQ = 50-70, 85% of cases, can live and work independently, at sixth grade level, problems with self esteem and impulse
control, co-morbid conditions include conduct disorders, substance use, ADHD; problems with mild MR may attenuate after patient completes schooling and can lead a normal life
- Moderate – IQ = 35-50, 10% of cases, live in residential communities (supervised living) and can work with support, at second grade level, problems conforming to social norms, Down syndrome common in this category
- Severe (IQ = 20-35) and profound (IQ < 20) – 4% and 1% of cases, little or no speech, live in highly supervised care settings, limited ability to care for themselves
- Etiology – most cases are idiopathic in origin, other causes include genetic or chromosomal abnormalities, pregnancy/perinatal problems, general medical conditions, environmental factors
- Onset and course – onset is before 18 years of age, developmental milestones are delayed, patients have a childlike presentation, 1.5:1 male to female ratio
- Treatment – prevention is the goal with genetic counseling, safe environments, etc; treat
other medical conditions, provide special education, behavioral therapy and a supportive environment.