The full spectrum
In 1911, Swiss psychiatrist Paul Bleuler published a 500-plus-page book about disorders characterized by difficulties with understanding emotions, reading social cues and thinking about others' beliefs.
Sounds a lot like autism, doesn't it? Bleuler's subject was actually schizophrenia or, as he called it, "the group of schizophrenias."
Scientists have debated the relationship between autism and schizophrenia for decades. The two disorders are different in many obvious ways — autism crops up in childhood and is marked by an indifference toward other people, whereas schizophrenia appears in adolescence or adulthood and often comes with paranoid thoughts and delusions about others.
But a review published last month suggests that they are two sides of the same neurobiological coin.
As Bleuler first noted, people with schizophrenia, like those with autism, have deficits in 'Theory of Mind:' the ability to infer what other people are thinking. A study published this summer, for example, shows that people with schizophrenia consistently score poorly on Theory of Mind tests.
Autism and schizophrenia also share intriguing abnormalities in the brain, such as a smaller-than-normal corpus callosum, the bundle of nerve fibers that connect the right and left hemispheres. And both disorders have been linked to disruptions in mirror neurons, cells that fire when you perform an action or watch someone else do so.
Most persuasive to me is their genetic overlap. About one percent of the population has autism, and one percent has schizophrenia. If the two had no relationship, then the probability of someone having both disorders would be one-hundredth of a percent.
In fact, it's much higher: one study found that ten percent of adults with autism also have a schizophrenia-like illness. What's more, people with schizophrenia have a higher risk of having a child with autism. Both disorders have been linked to some of the same genetic variants, such as mutations in the SHANK3 gene.
The new review notes several ways in which the same initial insult — whether a disruption in a gene or a particular brain circuit — could unspool. For example, the key difference could be timing: if a glitch happens at one point in early development, it leads to autism, whereas if it happens at a slightly different time, it causes schizophrenia. A better understanding of the link between autism and schizophrenia could help clinicians diagnose and treat each condition. For now, it's safe to say that psychiatric disorders don't belong in black-and-white categorical buckets, but rather on a full and colorful spectrum.
Comments
A very nice post - that I arrived at from a tweet. (I hope to find the the tweet and re-tweet it.) Now to read some of the links within.
Virginia;
You correctly state that autism is defined by an indifference to other people. However, that is not what current diagnostic criteria for autism states (DSM-IV-TR, ICD-10). Current definition includes twelve isolated symptoms, none of which are specific to autism suggesting substantial ambiguity in autism definition. That definition defines autism as a 'qualitative impairment in recpirocal social interaction'. There is a huge difference between an autistic child with an indifference to the existence of other people, including parents and siblings and the social problems in say Fragile X mentally retarded boys whose social problems are that of social anxiety and shyness or in the symptoms of schizophrenia.
This broad expansion of diagnostic concepts, beginning in 1994 with the introduction of DSM-IV and ICD-10 may be responsible for the so-called 'autism epidemic'. If you throw too wide a net you catch all the wrong kinds of fish.
This is nothing new in the brief history of autism. In 1957, Leo Kanner joined Van Krevelan in objecting to the 'abuse of the diagnosis of autism' that 'threatens to become a fashion'.
http://neurodiversity.com/library_kanner_1965.html
:
Kanner wrote:
'In the same year, Clemens Benda included in his book, Developmental Disorders of Mentation and Cerebral Palsies, a brief chapter with four illustrations, entitled "The Autistic Child". In it, he wrote: "The great question is whether autism is a part of the schizophrenic syndrome complex or should be considered a separate entity. A decision of this question cannot be made without a more thorough discussion of what constitutes childhood schizophrenia."
This sage advice was not heeded by many authors. While the majority of the Europeans were satisfied with a sharp delineation of infantile autism as an illness sui generis, there was a tendency in this country to view it as a developmental anomaly ascribed exclusively to maternal emotional determinants. Moreover, it became a habit to dilute the original concept of infantile autism by diagnosing it in many disparate conditions which show one or another isolated symptom found as a part feature of the overall syndrome. Almost overnight, the country seemed to be populated by a multitude of autistic children, and somehow this trend became noticeable overseas as well. Mentally defective children who displayed bizarre behavior were promptly labeled autistic and, in accordance with preconceived notions, both parents were urged to undergo protracted psychotherapy in addition to treatment directed toward the defective child's own supposedly underlying emotional problem.
By 1953, van Krevelen rightly became impatient with the confused and confusing use of the term infantile autism as a slogan indiscriminately applied with cavalier abandonment of the criteria outlined rather succinctly and unmistakably from the beginning. He warned against the prevailing "abuse of the diagnosis of autism," declaring that it "threatens to become a fashion." A little slower to anger, I waited until 1957 before I made a similar plea for the acknowledgment of the specificity of the illness and for adherence to the established criteria'.
Virginia;
As per 'Theory of Mind' impairments being shared by autism and schizophrenia patients are concerned, quite right. However 'Theory of Mind' impairments have also been observed in adult stroke patients:
http://www.ncbi.nlm.nih.gov/pubmed/10384736
'Theory of Mind' impairments are neurologically based but not a specific diagnosis based phenomena.
Hi RAJ,
Thanks, as always, for reading SFARI.
You make some good points -- certainly there have been significant changes in the diagnostic criteria for autism and schizophrenia over the years, and it seems plausible to me that that could partly account for some of the observed behavioral similarities.
Is it your belief that 'autism', per se, does not actually exist?
Assuming for the moment that autism is a distinct condition, it's quite striking to me that a disproportionately high number of children with autism have mothers and fathers with other psychiatric conditions, including, notably, schizophrenia and bipolar disorder. It seems like many lines of evidence are converging on the idea that 'autism' risk genes cause glitches that, depending on a host of developmental and environmental factors, can result in an array of impairments (and therefore, different diagnoses).
"Most persuasive to me is their genetic overlap. About one percent of the population has autism, and one percent has schizophrenia. If the two had no relationship, then the probability of someone having both disorders would be one-hundredth of a percent.
In fact, it's much higher: one study found that ten percent of adults with autism also have a schizophrenia-like illness."
The second paragraph doesn't follow directly upon the first. The way it is written, some might think that the comparison is between 0.01% and 10%.
If the data above are correct, schizophrenia symptoms are more common in autitics--but the comparison is between 1% and 10%.
Yes, 1 in 10,000 of the general population should have schizophrenia and autism if they are unrelated.
However, 1 in 100 of autistics (1%) should have schizophrenia.
Hi Sullivan,
Thanks for the close reading! You're right, the way I put these two statistics together is somewhat misleading.
The bottom line is the same, though: One study found that ten percent of adults with autism also have a schizophrenia-like illness, which is much higher than the expected one percent.
Virginia;
Autism does exist,it is simply being vastly over diagnosed. For example. Angelmans Syndrome involves genetic mutations in the region of chromosome 15Q12 where the UB3A gene is located. Angelmans Syndrome usually involves severe mental retardation, seizures and gross motor incoordination. Angelmans syndrome individuals have been reported in the AGRE multiple incidence family data base. Most cases are the consequence of a de novo mutation and is not inherited.
http://ghr.nlm.nih.gov/condition/angelman-syndrome
Specialists in autism see autism in Angelman Syndrome childen, but the parents, families, therapists, clinicians and researchers who specialize in Angelmans syndrome and who have joined in a collaboratve effort, much like Autism Speaks, in an organization called the Angelmans Syndrome Foundation:
http://www.angelman.org/
They unequivocally state that Angelmans Syndrome is often misdiagnosd as cerebral palsy or autism:
http://www.angelman.org/stay-informed/
Who would you believe with respect to Angelmans syndrome, autism specialists who see autism everywhere, including virtually the entire advisory board of the Simons Foundation, or those who actually are the most closely involved in understanding the causes of this devastating disorder? I'l go with those who are most closely involved and have a greater understanding of what Angelmans syndrome is all about rather than SAFRI autism experts..
Wow! This is so interesting. Especially since my son has Paranoid Schizophrenia(28) and the young great nephew we have custody of is diagnosed aspergers autism. (6 years old) It is my prayer that this study will enhance their lives.
I have an autistic grandchild and others in my extended family, as well as many instances of scizophrenia. I have documented this, diagnosed and undiagnosed schizophrenia, as far back as four genereations. My husband's family has instances of Asbergers. I am looking to send this info to researchers in the field. Can any one help put me in contact with the appropriate people?
Sylvia,
The lead author of the review I blogged about here is Bryan King at the University of Washington. His contact information is here: http://depts.washington.edu/chdd/iddrc/res_aff/king.html.
Judith Rapaport of the National Institute of Mental Health has also studied the connection between autism and schizophrenia. You can read about her work here: http://health.usnews.com/health-news/blogs/on-parenting/2008/03/31/autism-and-schizophrenia-linked.html. Her contact information is: http://neuroscience.nih.gov/Lab.asp?Org_ID=134.
Hope this helps. Thanks for reading SFARI!