Britney Spears fears Jayden James, the youngest of her two sons with ex-husband Kevin Federline, may be autistic.

Compared to his big brother, Sean Preston, little Jayden “often seems to be in his own world,” family friends say.

“He plays alone a lot,” an In Touch Weekly snitch says. “Jayden often starts crying for no apparent reason,” a friend of K-Fed’s adds.

Britney and Kevin are planning to have the 1-year-old tested for the neurological disorder that affects communication skills, in addition to a host of other developmental conditions.

“Kevin wants Jayden tested to rule out any developmental problems,” a Federline insider dished to In Touch.