One of the happiest outcomes of the diametric model of mental illness is that, for the first time ever, the striking difference between the early age of onset of autism spectrum disorders (ASDs) as opposed to the relatively late age of onset of psychotic spectrum disorders (PSDs) is readily explained. According to the model, this is simply the result of the fact that ASD is symptomatically hypo-mentalistic, and represents a failure to complete a normal process of development of mentalism, (aka theory of mind skills). PSD, by contrast, is according to the model symptomatically hyper-mentalistic, implying that the normal period of development normally needs to be completed before mentalism can become pathologically over-developed as classically seen, for example, in paranoid schizophrenia, as I describe at length in The Imprinted Brain.
But the theory does not preclude the possibility that potential sufferers from PSD later in life might nevertheless show signs of being on a hyper-mentalistic developmental trajectory during childhood, somewhat in the way in which very talented people can show outstanding gifts in their youth, and long before they acquire their adult expertise. Furthermore, the analogy is a good one because it features something that is distinctive about the diametric model by comparison to conventional views. This is the logical implication that, even though mentalism may be as pathologically over-developed in psychotics as it is under-developed in autistics, such enhanced development might nevertheless confer real benefits in certain respects.
This is something that psychiatrists have been noticing since Blueler commented that schizophrenics who seem totally withdrawn and uninterested in their environment nevertheless “pick up an astounding amount of information from snatches of conversation about the personal lives of their doctors and care personnel, and about tensions among them.” Nor is this simply anecdotal: experimental evidence shows that borderline personality disorder patients do better than normal controls in a virtual trust game demanding mentalistic skills, as described in an earlier post. Indeed, one of the most arresting possibilities of this line of reasoning is that, just as there are autistic savants with remarkable mechanistic cognitive abilities, so there might be psychotic savants with the corresponding mentalistic gifts, as I pointed out in a previous post and speculate about in an online interview.
All this is in sharp contrast to conventional views, which assume that any deviation from normal mentalizing in ASD or PSD must be detrimental to mental functioning, and implies that tests of mentalistic competence in such cases will always reveal deficits and failures. Frustratingly for the diametric model, this is the assumption built into a new Danish study entitled, Hyper-Theory-of-Mind in Children with Psychotic Experiences (below).
The study started from the fact that
Hallucinations, delusions and other psychotic symptoms in the absence of diagnosable psychotic illness occur frequently in the general population. Recent meta-analyses found a median prevalence of such non-clinical Psychotic Experiences (PE) of around 7% in the general population of all ages, and around 17% in the subgroup of children aged 9–12 years. PE are usually transitory, but longitudinal cohort studies have shown an association with later development of psychotic illness, indicating that PE may index psychometric risk for psychotic disorder.
The aim of the study was to examine the specific patterns of alterations of what the authors call “Theory of Mind (ToM and HyperTom)” or what I would call mentalism and hyper-mentalism in relation to psychotic experiences in children, “in order to expand current knowledge on the role of ToM in the aetiology of psychosis.”
As the diametric model would predict given that block design (BD) is a skill at which autistics often do better than normal, the study found that “The HyperToM group (…) had a significantly lower BD score than the Non-HyperToM group (…).” And as the model would also lead you to expect, the children “with low ToM” did not have a significantly increased risk of having psychotic experiences compared to the children with ”high ToM.” But the children with ”HyperToM” had an increased risk of psychotic experiences compared to the children without it. Even more to the point, the authors report that their results suggest that hyper-mentalism in childhood is particularly associated with psychotic experiences, “and that this association is strongest for delusional ideas with paranoid content (…), i.e, delusions of persecution, mind-reading and/or receiving messages from TV/radio.”
The authors of this study go on to note that
it may be argued that development of ToM abilities, including the awareness of intentions of the self and others, is necessary in order to experience ideas of reference and symptoms like mind reading. Clearly, paranoid patients have intact ToM in the sense that they know that other people have mental states, but may perform poorly because of their difficulties in accurately monitoring other people’s intentions.
Indeed, as they also note and as the diametric model also predicts,
A retrospective study of young patients with schizophrenia found an increased likelihood of delusional beliefs with age, indicating that the formation of these symptoms from pre-adolescence onwards depend on brain maturation and learning. Similarly, HyperToM may also depend on brain maturation and learning. The immaturity of the more advanced aspects of ToM abilities in pre-adolescent children may increase the likelihood of social misinterpretation, anxiety and formation of paranoid and first-rank like delusional ideation that may ultimately result in the persistence of PE.
The study notes that “Our findings suggest that it may be productive to apply more differentiated measures of ToM instead of relying on an overall score based on number of correct answers,” and in another post I drew attention to just such a study which was able to distinguish between normal mentalizing, over-mentalizing, under-mentalizing, or not metalizing at all. Clearly, we need longitudinal studies that include unbiased measures of mentalism in all these respects and which also take into account alternatives to conventional wisdom, such as the diametric model.
(With thanks to Bernard Crespi for bringing this to my attention.)