III. AGE AT ONSET, COURSE, PREVALENCE

AGE AT ONSET:
Usually apparent by age 7 (2nd grade), sometimes age 6 (1st grade) (DSM-III, 1987).
Sometimes up to age 9 if a Developmental Reading Disorder is compensated for in school (DS-III-R, 1987).

COURSE:
If mild, with therapy, there are no signs in adulthood (DSM-III-R, 1987).
If severe, it could persist through adulthood (DSM-III-R, 1987).

PREVALENCE of dyslexia in poplulation:

3% to 6% of school-aged children (Council on Scientific Affairs, 1989)
4% of school-aged children (DSM-IV, 1994).
40% to 70% of those participating in prison programs (“Dyslexia and the adult learner,” 1994).
60% and more of those in adult literacy programs (“Dyslexia and the adult learner,” 1994).
40% to 60% of those in basic adult education programs (“Dyslexia and the adult learner, ” 1994).

GENDER NOTE:
60% to 80% of individuals diagnosed with Reading Disorder (Dyslexia) are males. This disorder is more equal in both males and females when careful criteria is used as opposed to the traditional school based referral and diagnostic procedures (DSM-IV, 1994). Therefore, the previous ratios of four males to each female diagnosed with dyslexia are a result of the diagnosis. However, males often manifest more severe cases of dyslexia and behavioral disorders, like ADHD (National Institute of Child Health and Human Development–Human Learning and Behavior Branch, Center for Mothers and Children, 1992).