WASHINGTON (AP) — Early diagnosis is considered key for autism, but minority children tend to be diagnosed later than white children. Some new work is beginning to try to uncover why — and to raise awareness of the warning signs so more parents know they can seek help even for a toddler.

“The biggest thing I want parents to know is we can do something about it to help your child,” says Dr. Rebecca Landa, autism director at Baltimore’s Kennedy Krieger Institute, who is exploring the barriers that different populations face in getting that help.

Her preliminary research suggests even when diagnosed in toddlerhood, minority youngsters have more severe developmental delays than their white counterparts. She says cultural differences in how parents view developmental milestones, and how they interact with doctors, may play a role.

Consider: Tots tend to point before they talk, but pointing is rude in some cultures and may not be missed by a new parent, Landa says. Or maybe mom’s worried that her son isn’t talking yet but the family matriarch, her grandmother, says don’t worry — Cousin Harry spoke late, too, and he’s fine. Or maybe the pediatrician dismissed the parents’ concern, and they were taught not to question doctors.

It’s possible to detect autism as early as 14 months of age, and the American Academy of Pediatrics recommends that youngsters be screened for it starting at 18 months. While there’s no cure, behavioral and other therapies are thought to work best when started very young.

Yet on average, U.S. children aren’t diagnosed until they’re about 4½ years old, according to government statistics.

And troubling studies show that white kids may be diagnosed with autism as much as a year and a half earlier than black and other minority children, says University of Pennsylvania autism expert David Mandell, who led much of that work. Socioeconomics can play a role, if minority families have less access to health care or less education.

But Mandell says the full story is more complex. One of his own studies, for example, found that black children with autism were more likely than whites to get the wrong diagnosis during their first visit with a specialist.

At Kennedy Krieger, Landa leads a well-known toddler treatment program and decided to look more closely at those youngsters to begin examining the racial and ethnic disparity. She found something startling: Even when autism was detected early, minority children had more severe symptoms than their white counterparts.

By one measure of language development, the minority patients lagged four months behind the white autistic kids, Landa reported in the Journal of Autism and Developmental Disorders.

It was a small study, with 84 participants, just 19 of whom were black, Asian or Hispanic. But the enrolled families all were middle class, Landa said, meaning socioeconomics couldn’t explain the difference.

One of the study’s participants, Marlo Lemon, ignored family and friends who told her not to worry that her son Matthew, then 14 months, wasn’t babbling. Boys are slower to talk than girls, they said.

“I just knew something was wrong,” recalls Lemon, of Randallstown, Md.

Her pediatrician listened and knew to send the family to a government “early intervention” program that, like in most states, provides free testing and treatment for young children’s developmental delays. Matthew was enrolled in developmental therapy by age 18 months, and was formally diagnosed with autism when he turned 2 and Lemon enrolled him in Kennedy Krieger’s toddler program as well. In many of his therapy classes, Lemon says, Matthew was the only African-American.

Now 7, Matthew still doesn’t speak but Lemon says he is making huge strides, learning letters by tracing them in shaving cream to tap his sensory side, for example, and using a computer-like tablet that “speaks” when he pushes the right buttons. But Lemon quit working full-time so she could shuttle Matthew from therapy to therapy every day.

“I want other minority families to get involved early, be relentless,” says Lemon, who now works part-time counseling families about how to find services early.

For a campaign called “Why wait and see?” Landa is developing videos that show typical and atypical behaviors and plans to ask Maryland pediatricians to show them to parents. Among early warning signs:

—Not responding to their name by 12 months, or pointing to show interest by 14 months.

—Avoiding eye contact, wanting to play alone, not smiling when smiled at.

—Saying few words. Landa says between 18 and 26 months, kids should make short phrases like “my shoe” or “where’s mommy,” and should be adding to their vocabulary weekly.

—Not following simple multi-step commands.

—Not playing pretend.

—Behavioral problems such as flapping their hands or spinning in circles.

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EDITOR’s NOTE — Lauran Neergaard covers health and medical issues for The Associated Press in Washington.

Copyright 2012 The Associated Press.