Here is a study from Wisconsin University regarding protective headgear and concussions. Although the study relates to soccer specifically, I would imagine that the findings would be quite the same for basketball.
www.med.wisc.edu
I have questions about this study.
1. They had 88 schools with girls teams and divided them in half. But they don't report the number of active athletes in each group. (But the original article did.)
2. Many soccer players sit out whole games, some play a few minutes in a game, so game+practice minutes could vary widely amongst the players. The rate of concussions per active minute would be a useful stat, and since they "used licensed medical professionals in the field to record the onset" they should have been able to provide that information.
3. The headline touts "does not prevent", but this quote appears in the body of the article: "the rate of a sport-related concussions sustained by male and female players wearing specific headgear models varied a great deal. The authors found that the rate of these injuries ranged from 2.7% to 5.9%
depending on the type of headgear worn by the players." (emphasis mine).
4. The original article provided rates per 1000 "Athletic Exposures (AE)", but didn't define that term. Some could have been 1 minute, some 80 minutes.
I found the article, so here's the full quote for point 3: "Overall, the SRC incidence ranged from
2.5% (HR: 0.54 (0.20–1.43), p=0.213) for players wearing the Storelli ExoShield to
5.4% (HR: 1.09 (0.62–1.91), p=0.765) for players wearing the Ultra Forcefield Sweatband." (emphasis mine)
In other words, the results for
the random mix of head gear (each girl got to choose which of the 5 models in the study they wanted to wear) was "no difference from no head gear", but different models had different results. Not a very useful result, and does not, IMO, justify the claim of "does not prevent" without giving many qualifications that the study report does not present.