sorry i have not hear about this before. i have listen about dog became crazy.
Altering your dog between 6 and 9 months of age seems to be a completely safe option. This is when I spay my bitches; generally right before their first heat. This keeps their "girly parts" nice and small and does not seem to affect their musculature in any way. I have never had any of my spayed females get fat either. Spayed females getting fat is a myth. However, I will say that I have had more than one spayed female develop incontinence problems which can be a real pain.
With my male dogs which are going into police detection work or pet homes, I neuter them between 6 and 9 months. This has proved satisfactory for me. Dogs which are going to be worked in weight pull but not bred I would not neuter until they were closer to 24 months.