Comorbid

I've been meaning to write about this topic for some time but never quite got around to it. Now seems like as good a time as any so here goes.

A lot of people discuss certain medical symptoms and conditions, that may or may not be more common in autistic children, as if these disorders are either linked to the etiology of autism or and integral component of autism. For some reason many parents of autistic children become offended when these symptoms are described as comorbid to autism because they see these things as part of autism. I'm not saying that some autistic children aren't also afflicted with various health issues but let's look at reasons why they are often described as comorbidities and why some would prefer to see these things recognized as symptoms of autism.

First the Definition of Comorbidity
Comorbidity: The coexistence of two or more disease processes.

That's a very simple definition from a medically oriented website but it's a pretty straightforward and more or less accurate definition. The only way this definition works for autism is when one of the two or more diseases is autism. Right there we have a problem because autism cannot accurately be described as a disease. Not with our current knowledge of the biology of autism, it can't.

For the sake of discussion, we'll need to accept that medical professionals will most likely define autism as a medical condition, to some extent, and other medical conditions will be described as co-existing disease processes as long as one doesn't clearly cause the other. That probably won't please many of us but that's the way it usually works.

The definition of comorbidity can also change according to context. In some circles it's perfectly acceptable to describe two or more psychiatric disorders or behaviors as comorbidities.

The presence of multiple disorders in one individual. Pathological gambling has high rates of comorbidity with disorders such as alcoholism and depression.

Unless it becomes widely recognized that drinking causes gambling, gambling causes depression, and depression causes alcoholism, rates of comorbidity will be used to describe the relationship between these conditions. As long as Casinos serve alcohol in attempt to impair gambling decisions, patrons will become depressed after losing money which may cause some to drink. Clinical depression isn't a symptom of gambling losses and alcoholism doesn't promote gambling, for the most part.

The Symptoms of Autism

There's a reason why the DSM-IV description for autism doesn't include things like GI distress, diarrhea, constipation, immune abnormalities, allergies, etc. Autism can be diagnosed in people with any number of other medical or psychiatric conditions and the diagnosis doesn't rely upon physical, medical, or biological parameters. That's one of the reasons we know that autism can be diagnosed more often with Down Syndrome, Fragile-X, Prader Willi Syndrome, Rett Syndrome, etc. Depending on how autism is described, autism itself might be seen as a comorbidity. Autism doesn't cause those other conditions and those conditions can exist without autism.

When Andrew Wakefield decided to investigate GI symptoms in a handful of autistic children, they weren't randomly selected. Parents who were concerned about their autistic child's GI issue sought medical attention from a gastroenterologist. No doubt he saw a strong correlation between autism and GI symptoms. A GI specialist may be more inclined to think that GI inflammation can cause autism in the same way an economist might leap to the conclusion that correlation implies causation. If this particular GI specialist claims to have previously detected the measles virus in the GI tracts of patients with Crohn's Disease, he might be inclined to connect reports of autistic regression with exposure to the measles component of the MMR. It's also likely that these same parents saw a correlation and shared their observations with Dr. Wakefield but we can't be sure.

Whatever the sequence of events, Wakefield reported a relationship between Ileal-lymphoid-nodular hyperplasia, autism, and the presence of the measles virus. Even if he didn't specifically say that one cause the other, he did nothing to dispel the obvious conclusions drawn form his work. One doesn't coin the term autistic enterocolitis and describe the presence of the measles virus only in autistic children without implying a relationship. Of course the relationship was more than implied in the years to follow and we now have a pretty good idea of where he went wrong with the PCR techniques but I don't expect Wakefield will ever come out and admit that he was wrong. We'll probably see more emphasis placed on GI inflammation as he argues that his actions were justified given the circumstances.

Is there a higher rate of GI disturbances and gut inflammation in autistic children? Possibly, maybe even probably. My personal opinion, based on my own observations leads me to believe so but I am willing to accept data from well designed studies if it shows otherwise. So far it looks like there are higher rates but the debate is far from over. Wakefield didn't just claim a relationship between ASD's and GI symptoms. He claimed a relationship between highly specific patterns of GI inflammation, exposure and detection of vaccine strain measles virus, and regressive autism. The presence of all or absence of 1 of 3 could make or break the diagnosis of "new variant inflammatory bowel disease."

Based on Wakefield's requirements, how many autistic children would be eligible for the diagnosis - Measles-mumps-rubella-induced regressive autism. None, apparently, since no other labs are able to confirm the presence of the measles virus and it's difficult to find a doctor ready and eager to scope children without good reason, autism or not.

Should we include nodular lymphoid hyperplasia in the DSM-V diagnostic criteria for autism? Of course not. Even when it's reported along with Bannayan-Riley-Ruvalcaba syndrome , autism and PTEN mutation. The traits that make this person autistic are still described as autism and comorbid conditions are described with different medical terms. Never will the word autism be used to communicate a broad range of physical medical disorders.

Idiopathic Autism

According to Wikipedia, the word idiopathic means arising spontaneously or from an obscure or unknown cause. Idiopathic Autism has become somewhat of a catch-all phrase where a cause, most often genetic, is unknown. Although the majority of autism falls into this category, this does not mean the majority of autism is the same thing. Before we had the tools to identify genetic and environmental factors, it could be said that all autism was idiopathic autism. Unfortunately, when a cause isn't identified, the void may be filled with any number of less plausible hypotheses. This phenomenon isn't unique to autism but no where else can we witness such a low standard of scientific accountability.

Autism By Any Other Name

I can't count the number of times I've heard it said that one type of autism or autistic-like behaviors aren't the same as this autism, core autism, idiopathic autism, HF, LF, AS, Whatever. Just stop it already. If a person is diagnosed as autistic, that's autism, alright? Whether it's part of Cri du chat syndrome or a creatine transport deficiency, if the label is applied it can't be peeled away by amateur diagnosticians on internet mailing lists. If a diagnosis gets counted under total number of cases which in turn is held up as evidence of an autism epidemic, you don't get to break out individual causes as it serves your agenda.

At this point we haven't found a single thing that causes autism each and ever time. True, there are certain genetic conditions associated with autism, there are several substances and infectious agents that may increase the chances of having an autistic child following prenatal exposure, and there are many suspected prenatal and perinatal risk factors under investigation.

No single gene, environmental factor, combination of genes and/or environment, or other risk factors, can consistently cause autism. I doubt that we will find such a gene or agent but we will most certainly continue to identify new causes, potential treatments, comorbidities, categories, and labels cleaved from the idiopathic autism realm. There's a lot to sort out before we can say that one thing is caused by another so our only option for now is to ignore symptoms that may or may not be associated with being autistic, or continue to discuss these things as potential comorbid conditions. Humans will always sort, catalog, and label all we encounter. We need to exercise great caution when we approach categorizing humans by comorbidities.