Interesting idea, Icabod
But mightn't that be considered concealing evidence? If she had been diagnosed with something like severe depression and was (or is) being prescribed medication, then that is an important aspect of her emotional / mental state that is being withheld from the court.
Perhaps that could explain why there is a glaring absence of medical professionals testifying?
No, I don't think it could be considered as concealing evidence
Kate has not taken the stand, afterall, she has not at any time ( as far as I am aware ) made any mention of
any medical treatment/drug therapy she has recieved for depression
In court all we have heard is second hand 'hearsay' regarding Kate's suicidal depression
It has always been that way ... the McCanns rarely commit to anything, leaving it to others to 'assume'
Anything 'assumed' by others, of course, in entirely deniable by the McCann themselves, if push comes to shove