About 4,440 local public school students are autistic, a number that has quadrupled during the last decade, according to new figures from the California Department of Education.
The figure represent a rise of about 300, or 8 percent, from 2012 to 2013.
Statewide, the number of autistic students rose by 6,300, or 9 percent, to almost 79,000. The number of autistic students statewide has risen by between 5,000 and 7,000 most years for more than a decade. In 2001, there were about 14,000 autistic students in the state.
Theories for the rise, which is a nationwide phenomenon, include improved autism screening, broader definitions of the condition and a genuine increase in autism cases.
A University of California study concluded that changes in diagnoses patterns alone cannot explain the rise in the disease. Instead, the study postulated that environmental factors were partially to blame and called for more study of the effects of viruses, pesticides, chemicals and other substances on the development of autism.
This chart shows the number of students with autism in the four-county region over the last decade.