|The thing about perfection is that it's unknowable.|
I'm not going to dwell too long on this paper aside from suggesting that such results add to a growing trend in psychiatry asking whether our current compartmentalising way of diagnosing mental health issues is actually fit for purpose à la RDoC (Research Domain Criteria). A few weeks back Virginia Hughes talked about 'Category Fail' based to a large extent on the paper by London  who suggested that: "The use of autism as a diagnostic category guiding translational research is fraught with so many problems that the validity of research conclusions is suspect." Sentiments which have been rumbling on for quite a few years now.
The Mancuso results are complemented by quite a few other findings suggestive of fuzzy boundaries when it comes to giving psychiatric labels and their associated qualities. Plucking randomly from the peer-reviewed literature, the paper from Silver & Bilker  for example, talking about people with schizophrenia showing "impairments in [the] recognition of identity and emotional facial clues" as part of social cognition carries hints of what has been described in cases of autism for example. The findings reported by Langdon and colleagues  talking about a specific Theory of Mind (ToM) impairment in their cohort with early psychosis provides further evidence for the non-exclusivity of this concept when similarly talked about with autism in mind (see here). I might add that I'm not a great fan of the link between ToM and autism anyway.
Of course, one might also see the concept of a spectrum of psychiatric conditions to be itself rather too simplified when it comes to describing and categorising behaviours and actions. The growing pluralisation of autism - 'the autisms' - and schizophrenia - 'the schizophrenias' - perhaps implies that 'tapestry' might be a better way to define presented symptoms, bearing in mind the potential number of permutations of displayed symptoms and underlying genetic/biological issues that may be evident. It might also cover the evidence talking about overlapping spectrums also.
It's all getting rather complicated...
Music: Chase & Status - Lost & Not Found.
 Mancuso SG. et al. A comparison of schizophrenia, schizoaffective disorder, and bipolar disorder: Results from the Second Australian national psychosis survey. J Affect Disord. 2014 Sep 30;172C:30-37.
 London EB. Categorical diagnosis: a fatal flaw for autism research? Trends Neurosci. 2014 Nov 14;37(12):683-686.
 Silver H. & Bilker WB. Social cognition in schizophrenia and healthy aging: Differences and similarities. Schizophr Res. 2014 Nov 15;160(1-3):157-162.
 Langdon R. et al. Theory of mind and neurocognition in early psychosis: a quasi-experimental study. BMC Psychiatry 2014, 14:316
Mancuso SG, Morgan VA, Mitchell PB, Berk M, Young A, & Castle DJ (2014). A comparison of schizophrenia, schizoaffective disorder, and bipolar disorder: Results from the Second Australian national psychosis survey. Journal of affective disorders, 172C, 30-37 PMID: 25451392