brain ****
brainpower
learning ability
mental capacity
mentality *
wit *

"There is nothing wrong with my mental capacity," she says.

"Our goal is to have two children who come out the same way they went in," without any loss of mental capacity, he said.

Finally she is on the floor, her mental capacity gone, few words remaining.

By another, her mental capacity, she was - and always will be - 8.

The question is whether to tell him that the young woman will always have the mental capacity of a 10-year-old.

When you're young, you have the mental capacity for a lot of races.

With the addition of language to the human culture came an increased mental capacity.

Also, in four of the seven, mental capacity was determined low.

His mental capacity is quite low as a result of the accident.

There was no point in employing his mental capacity without a good reason, after all.