Will someone who died at the age of 42, suffering from a severe developmental delay, be held accountable after the Resurrection?

If a person reaches the age of discretion and then becomes insane, he is held accountable for his state of mind before the insanity. However, if he was born or reached maturity lacking intellect, there is a difference of opinion among scholars regarding him. The preponderant view is that he is among the people of Paradise if he had Muslim parents, and it is also said that he will be tested in the Hereafter. As for one whose intellect has not departed, he is among those who are held accountable.