Concussion diagnoses have spiked in recent years as publicity about long-term brain damage has made head injuries more frightening, and Pennsylvania and New Jersey have among the highest rates in the nation, a new analysis of claims data by the Blue Cross Blue Shield Association has found.

The report, released Tuesday morning, found that the increase was particularly pronounced among 10-to-19-year-olds.  In that age group, concussion diagnoses increased by 71 percent from 2010 through 2015.  The growth in concussion rates for girls and young women was 118 percent, while it was 48 percent for boys and young men.

The biggest part of the increases occurred between 2010 and 2013, when many states were enacting laws that required medical clearance before young athletes suspected of having a head injury could return to training and playing.  Fall, the report said, is peak concussion season for young males.

The concussion rate increased for adults aged 20 through 64 as well, but not as steeply.  For them, it rose 26 percent.

Rates for post-concussion syndrome, in which symptoms last for weeks or months, also increased.  It was most common in older women.

The increases in diagnoses likely were not the result of more injuries,  said Don Liss, medical director for Independence Blue Cross in Philadelphia.  Independence is one of 36 Blue Cross or Blue Shield plans that belong to the association. They participate in the Blue Health Intelligence initiative, which produced the report, by sharing claims information.

There's no reason, Liss said, "to think there's been a fundamental change in how often those head injuries occur."

The report was based on an analysis of 936,630 diagnosed concussions involving commercially insured members.  It did not include data on how much those concussions cost the insurer or its members.  Liss said the treatment for concussion, which usually amounts to rest and avoiding stimulation, is not expensive.  The report did not look at whether there had been an increase in visits to pediatricians after sports injuries.

The report found considerable geographic variation in rates of diagnosed concussions. The mid-Atlantic and Northeast appear to be concussion hot spots while the South generally has lower rates.  Mississippi, for example, had the lowest concussion rate for 10-to-19-year-olds at  7 per 1,000 members in 2015, compared with 23.7 in New Jersey and 27.3 in Pennsylvania.  Only Massachusetts, at 27.5, had a rate higher than Pennsylvania's.

Liss said he believes the variation between states is also the result of "reporting bias" rather than differences in the number of injuries.  Pennsylvania may be high, he said, because doctors at Children's Hospital of Philadelphia have become authorities on concussions and have educated their colleagues in the region.

The report called for more study into possible reasons for state variations, including differences in state regulations and their implementation, participation in contact sports, and overall patterns of use of the health care system.

This is the ninth in the association's "Health of America Series."  Previous topics included cesarean sections, angioplasty and hip and knee replacements.