If troops in the missile attack had been wearing blast gauges, we would have quantifiable data on the amount of blast pressure they’d been exposed to — both for those who developed T.B.I. and those who did not. This would help the Defense Department better understand what level or type of exposure is problematic and inform designs for improved protective measures — helmets, bunkers or walls — against future attacks.

As a result of two years of bureaucratic foot-dragging inside the Defense Department, none of the troops hit by the Iranian missile attack were wearing the gauges.

The Iranian ballistic missile strikes could have caused brain trauma through a variety of mechanisms:

The primary mechanism is a wall of blast pressure from an explosion. Even relatively low levels of blast exposure can result in temporary cognitive deficits.

A secondary mechanism: Wind rushes to fill the vacuum left by the pressure wave. This can hurl shrapnel and fragments.

A tertiary mechanism: People or things can be thrown by this wind, leading to impact concussions.

A quaternary mechanism: Fires, toxic gases, burns or crashes can follow.

The non-primary mechanisms of injury are relatively easy to understand and protect against through traditional means such as body armor, helmets and fire-resistant uniforms.

The primary mechanism of injury — the blast pressure wave itself — is less understood. We don’t know whether servicemembers at Al Asad were injured by the blast pressure directly rather than being knocked over and hitting their heads. If Defense Department officials had done their jobs, that information could have been available.

Still, it’s clear that the Defense Department’s mandatory post-incident T.B.I. screening has advanced remarkably since the inconsistent mechanisms in the years of the Iraq and Afghanistan wars.

What has been slower to adjust is a culture that has approached concussions as something to be “shaken off” or worries that diagnoses may harm their careers.

Extensive public education has mitigated some of the cultural stigma of brain trauma diagnosis and treatment, but it still has a way to go. This is why the public communications from the White House and Pentagon have been such a bumbling disaster.