I think intellect is affected by trauma in this way:

The first reaction is to engage the fight response, or the flight response if fighting cannot work. If as a child neither of those is available, and the trauma situation continues and the person perceives their very survival to be at stake, then to preserve what is left of sanity the mind can shut off most other responses and go into almost a dormant state. It is a desperate move, but available if nothing else is, though it means any defenses are unavailable, and your survival depends on the attacker (I assume that is what is happening) being confused by your shutdown and quiting attacking.

I think that sort of thing happened to me, and the effects of the near shutdown of much thinking ability, and its replacement by pure instinct, lasted until puberty, and its effects are still noticeable today.