"The Out of Sync Child" Its written by an OT (Occupational Therapist) who specialises in Sensory Processing Disorder. Its just that 80% of people on the Autism Spectrum have SPD as well... so there is a huge amount of overlap, especially for those who are high functioning. Sometimes identifying the SPD and working with that is enough... sometimes you have to go further for other forms of help and that is when a diagnosis is helpful.