Tourette Syndrome and autism: room for diagnostic confusion

It is a concern that existing qualitative 'psychological' and checksheet-driven protocols that are used for diagnosing autism often produce false positive results for people who have Tourette Syndrome but are not on the autistic spectrum. There can be significant apparent symptom cross-over between the two conditions. Autism is a differential diagnosis for TS but rarely is TS regarded as a differential for autism, yet mistakes have occurred. Confusion is inevitable although can be limited by stricter interpretation of diagnostic characteristics. Although many with TS have social and sensory difficulties as well as obsessive thinking etc., that are shared with ASD (including Asperger Syndrome), there are several areas that are markedly different and are considered defining in ASD. These include an apparent reduced concern for other's feelings (although in Asperger's, empathy may be clear), a lack of awareness of the isolation and autonomy of the individual mind, less need to develop friendships, dislike of touching or being touched (but this may not be a true reflection of inner wants) and a seeming lack of imaginative play/behaviour. 


Although 'theory of mind' difficulties do occur in TS, many of these 'classic' ASD deficits are, conversely, strongly developed 'attributes' in TS. E.g: Expansive and highly-developed imaginative life, gregariousness, need for tactile contact, emotional hyper-responsivity and sometimes very overt concern and empathy for others and a need to express their 'feelings'. It also appears that some of the shared symptoms and 'characteristics' between the two disorders may have a very different origin and have their roots in differing neurological and psychological aetiologies. However an awareness that the two disorders may co-occur should always be considered. An often overlooked component that can play a central role in both TS and ASD is sensory hyper-sensitivity. Patients with either condition will often emphasise that such sensory problems cause some of their most significant difficulties.