Is there some kind of connection?
There are five points involved in this question, which I will name a to e and adress below. But first of all, two important caveats:
- As I say in my signature, I'm just a guy with a keyboard. So readers are encouraged to check by themselves my quotes and reasoning from them.
- The studies I quote were the most current on the subject when I researched it in november 2012. Therefore it is very likely that newer studies have been published on the subject, which can have confirmed or denied the findings of the quoted ones. Readers are encouraged to research for such newer studies.
For all studies, I provide the authors and the title but not the link, as that would cause this message to requiere admin approval. The studies can be found searching for the title in scholar.google.com.
a. What is the statistical relationship between both disorders? I.e., are they mutually exclusive in practice or do they coexist?
The traditional answer to this question, that "they are mutually exclusive", has been challenged in 2012 by two studies:
[a.1] Maria Unenge Hallerbäck, Tove Lugnegård, & Christopher Gillberg 2012. "Is autism spectrum disorder common in schizophrenia?"
Abstract:
A century ago, Kraepelin and Bleuler observed that schizophrenia is often antedated by “premorbid” abnormalities. In this study we explore how the childhood neurodevelopmental problems found in patients with schizophrenia relate to the current concept of autism spectrum disorder (ASD). Forty-six young adult individuals with clinical diagnoses of schizophrenic psychotic disorders were assessed. The Structured Clinical Interview for DSM Disorders (SCID-I) was used in face-to-face psychiatric examination of each individual. In 32 of the 46 cases (70%), collateral information was provided by one or both parents. The Diagnostic Interview for Social and Communication Disorders — eleventh version (DISCO-11) was used when interviewing these relatives. This instrument covers, in considerable depth, childhood development, adaptive functioning, and symptoms of ASD — current and lifetime. There is a strict algorithm for ASD diagnosis. About half of the cases with schizophrenic psychosis had ASD according to the results of the parental interview. The rate of ASD was strikingly high (60%) in the group with a SCID-I diagnosis of schizophrenia paranoid type. The findings underscore the need to revisit the DSM's “either or” stance between ASD and schizophrenia.
[a.2] Petra Waris, Nina Lindberg, Kirsi Kettunen, & Pekka Tani 2012. "The relationship between Asperger’s syndrome and schizophrenia in adolescence"
Abstract
Asperger’s syndrome (AS), a pervasive developmental disorder (PDD), has nowadays been widely advocated in media. Therefore, psychiatrists treating adolescents frequently meet patients as well as their families reporting of symptoms resembling those of Asperger’s syndrome. It is known that symptoms of Asperger’s syndrome have some overlap with those of schizophrenia, but less is known about comorbidity between these two syndromes. We describe a sample of 18 adolescents with early onset schizophrenia. Diagnosis of schizophrenia was based on assessment with Kiddie Schedule for Affective Disorders and Schizophrenia. The diagnostic interview for Social and Communication Disorders version 11 was used to assess autism spectrum disorders. Ten adolescents fulfilled symptom criteria of Asperger’s syndrome after the onset of schizophrenia, while only two persons had Asperger’s syndrome before the onset of schizophrenia, a prerequisite for diagnosis. 44 % of the adolescents fulfilled the diagnosis of some PDD in childhood. Most of them were, however, unrecognized before the onset of schizophrenia. On the other hand, all 18 patients had one or more symptoms of PDDS in adolescence. Adolescents with schizophrenia have often symptoms consistent with AS, although only few of them have fulfilled the diagnostic criteria in their childhood, a prerequisite for the diagnosis of AS. There is a risk for misdiagnosis of adolescents with autistic symptoms if detailed longitudinal anamnesis is not obtained.
b. What is the phenotypical relationship between both disorders? I.e., is the underlying phenomenon the same or different in each?
In order to answer that, we need plausible theories describing at least the main physical phenomenon underlying each disorder.
IMV, the currently most plausible such explanations are the "long-distance neural underconnectivity" for ASD, and the malfunction caused by neuronal oxidative/nitrosative stress for schizophrenia. If these are the actual cases, then there is no reason why the disorders should be mutually exclusive.
Therefore, if the severity of each disorder is measured along one of the two coordinate axes in a plane, x for ASD and y for schizophrenia, the traditional view is that cases could be exclusively along one of the axes, and the new view is that cases can have nonzero values of both coordinates.
c. Does having an ASD increase the probability of getting schizophrenia?
This question in turn can be asked on either the statistical or phenomenological level. Focusing on the second, some studies have observed in ASD cases a deficiency in the level of glutathion, which is the endogenous detoxifying agent that prevents oxidative and nitrosative stress.
Thus, ASD cases would be at greater risk of malfunction of neuronal systems due to oxidative/nitrosative stress, so that,
- if the malfunction occurs at higher functional levels, such as logical thinking, they get psychotic episodes like delusions and hallucinations, like you.
- if the malfunction occurs at lower functional levels, such as control of the immune system, they get Chronic Fatigue Syndrome, like Blade_Runner and myself.
Most aspies get neither because, when their neuronal energy production is impaired by nitrosative stress, they go the shutdown way instead of the malfunction way. And as the logical functional level shuts down, the limbic system takes over and you can get e.g. a fit of rage in males or a crying meltdown in females.
[c.1] Yusra A Al-Yafee, Laila Y Al- Ayadhi, Samina H Haq and Afaf K El-Ansary 2011
Novel metabolic biomarkers related to sulfur-dependent detoxification pathways in autistic patients of Saudi Arabia
Results
Reduced glutathione (GSH), total glutathione (GSH+GSSG), glutathione status (GSH/GSSG), ... were significantly lower, ... in autistics compared to control subjects.
Conclusion
The impaired glutathione status ... could be used as diagnostic biomarkers of autism.
[c.2] Mara Parellada, Carmen Moreno, Karina Mac-Dowell, Juan Carlos Leza, Marisa Giraldez, Concepción Bailón, Carmen Castro, Patricia Miranda-Azpiazu, David Fraguas, Celso Arango 2011
Plasma antioxidant capacity is reduced in Asperger syndrome
TAOS (total antioxidant status) was reduced in Asperger individuals compared with healthy controls and psychosis patients, after covarying by age and antipsychotic treatment. This reduced antioxidant capacity did not depend on any of the individual antioxidant variables measured. ... In conclusion, Asperger patients seem to have chronic low detoxifying capacity.
[c.3] Chauhan A, Audhya T, Chauhan V. 2012
Brain region-specific glutathione redox imbalance in autism
These findings indicate that autism is associated with deficits in glutathione antioxidant defense in selective regions of the brain.
[c.4] Penelope AE Main*, Manya T Angley, Catherine E O'Doherty, Philip Thomas and Michael Fenech 2012
The potential role of the antioxidant and detoxification properties of glutathione in autism spectrum disorders: a systematic review and meta-analysis
The findings of this systematic review support the assertion that children with autism spectrum disorders are more likely to have significantly lower tGSH and GSH and significantly increased GSSG, resulting in a significantly lower GSH:GSSG than children without autism.
d. What is the hereditary relationship between both disorders? I.e., what is their statistical correlation within families?
I remember a statistical correlation had been found, but I leave finding the relevant studies in scholar.google.com to people having the interest and will to do so.
e. What is the genetic relationship between both disorders? I.e., have any common genetic mutations been identified in both?
Though this is a field still very immature, I remember that some common genetic basis had been preliminary found. Again, I leave this answer to people willing to do the research.
