No, they never grow out of it. But they CAN adapt, sometimes so well that they are, to all intents and purposes, functionally normal. It's like the example I gave of the swan on the lake - the semblance of serenity is only on the surface, because underneath is a lot of furious activity, making it all possible.
One of my sisters was brain-damaged by fever as a young child. She was unable to learn much because of short-term and long-term memory problems, as well as being extremely anxious and emotionally insecure. She left school as soon as she was old enough legally. Through her life she has slowly been able to learn and adapt. She never could cope with stress and change very well, but as life has continued she has been able to, in her own way, deal with some amazing things. About ten years ago she went to evening classes and did a course in accountancy. Now she does the books for most of the family. She has owned and run her own business. She has raised three wonderful children and is enjoying her grandchildren. When she was finally emotionally strong enough she threw out her first husband (not a bad bloke, but she married him too young and too immature - she finally grew up) and has since remarried very happily.
To all intents & purposes, she is normal. She certainly has found her intelligence, which for years seemed locked away inside a frightened little girl. She is strong and capable. Nobody would believe the brain damage that we knew. But put her under sudden, severe stress and we see it - until she gets a grip on herself again. It's still there but she has adapted brilliantly.
I feel it's the same with Pervasive Developmental Disorder (PDD) - depending on how much support they have and what they're trying to overcome, they adapt brilliantly. But EVERYTHING for them is adapting and adjusting.
There are gifts, too, with Pervasive Developmental Disorder (PDD). There can be some wonderful benefits. There are adults with Pervasive Developmental Disorder (PDD) who claim that given the choice to wake up in the morning with no Pervasive Developmental Disorder (PDD), they would choose to keep their Pervasive Developmental Disorder (PDD) for the blessings it has brought them as well. They have done their best to overcome their difficulties and have even turned things to their advantage. They are loyal. Honest. Gifted. Loving and caring. Law-abiding. Trusting. A Pervasive Developmental Disorder (PDD) friend will stick by you.
Value your child, value what you have helped him accomplish and don't be too upset by those who don't see it. They're not meaning to devalue those efforts, they are, in their own ham-fisted way, paying tribute to all the work that they have not been privileged to see. But in order to continue to recognise that effort, always recognise that the Pervasive Developmental Disorder (PDD) is still there, just ever more brilliantly covered up.