For autism, Parkinson’s, hope for faster diagnosis

For many brain diseases, diagnosis is no exact science.
Because of the complexity of the brain and of the symptoms that it can cause,
there are often no definitive tests, and neurologists lean on years of
experience, long and painstaking observations, and educated guesses to
determine what exactly is afflicting their patients. Not only is this
frustrating for everyone involved, but in some cases a delayed diagnosis can
make a disease much more difficult or even impossible to treat successfully.

Now, scientists have made progress on faster, more objective
methods to detect at least two serious neurological disorders in which early
and correct diagnosis is vital.

A small pilot study conducted by Timothy
Roberts
and his colleagues at the Children’s Hospital of Philadelphia report
has found that a relatively unobtrusive brain-scanning technique may be useful
in detecting autism-spectrum
disorders
(ASD). These conditions, characterized by problems in
communication and social interaction, are often diagnosed after a child has
already begun school, when treatments to prevent reading and other learning
disabilities are less effective. They are also not that uncommon: A recent
study by the Centers for Disease Control and Prevention found that
almost 1 percent of children in the U.S. have an ASD
.

For the study,
reported online in the journal Autism
Research
this month, the scientists measured brain responses from 25
children with ASDs and 17 without using magnetoencephalography, in which a helmet
surrounding the head is used to measure the brain’s magnetic field. On average,
the ASD group had a tiny delay—about 11 milliseconds—in brain responses to
sounds. According to the researchers, this may be explained by one
of their previous studies
, which found that people with ASDs have reduced
amounts of white matter, or myelination, a type of insulating material that
speeds up transmission of nerve signals.

In the second study, slated
to appear in the February issue of Lancet
Neurology,
researchers from the Feinstein Institute for Medical
Research, led by David
Eidelberg
, used positron emission tomography (PET), which measures blood
flow and chemical changes in the brain, to successfully diagnose whether a person
had Parkinson’s disease, multiple system atrophy, or progressive supranuclear
palsy. These movement disorders often show nearly identical symptoms at the
start but require different types of treatments.

In 167 patients, a computer program analyzing PET results
matched the diagnosis made by experienced specialists more than 80 percent of
the time. The doctors, however, had spent an average of 2.6 years assessing the
patients before coming to their judgments.

It remains to be seen whether the results of their studies
will end up reaching the doctor’s office, as many promising brain-scan findings
have ultimately failed to be precise or accurate enough upon additional testing.
The ASD study, for instance, looked at an extremely small number of people and tested
children with an average age of 10; it’s unknown whether such a delay would
still be detectable in young children or infants, for whom early diagnosis
would offer the most advantages.

The computer program used in the PET work will likewise need
additional testing through large, double-blind studies, according to the study
authors. But if confirmed, the findings could extend beyond better diagnosis,
they say; the research may also spur drug development for movement disorders by
allowing doctors to identify candidates for clinical trials much earlier than
previously possible.

—Aalok Mehta

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