Evidence of Mitochondrial Dysfunction in Autism and Implications for Treatment
Daniel A. Rossignol, J. Jeffrey Bradstreet, International Child Development Resource Center,
"Classical mitochondrial diseases occur in a subset of individuals with
autism and are usually caused by genetic anomalies or mitochondrial
respiratory pathway deficits. However, in many cases of autism, there is
evidence of mitochondrial dysfunction (MtD) without the classic
features associated with mitochondrial disease. MtD appears to be more
common in autism and presents with less severe signs and symptoms. It is
not associated with discernible mitochondrial pathology in muscle
biopsy specimens despite objective evidence of lowered mitochondrial
functioning. Exposure to environmental toxins is the likely etiology for
MtD in autism. This dysfunction then contributes to a number of
diagnostic symptoms and comorbidities observed in autism including:
cognitive impairment, language deficits, abnormal energy metabolism,
chronic gastrointestinal problems, abnormalities in fatty acid
oxidation, and increased oxidative stress. MtD and oxidative stress may
also explain the high male to female ratio found in autism due to
increased male vulnerability to these dysfunctions.
Biomarkers for
mitochondrial dysfunction have been identified, but seem widely
under-utilized despite available therapeutic interventions. Nutritional
supplementation to decrease oxidative stress along with factors to
improve reduced glutathione, as well as hyperbaric oxygen therapy (HBOT)
represent supported and rationale approaches. The underlying
pathophysiology and autistic symptoms of affected individuals would be
expected to either improve or cease worsening once effective treatment
for MtD is implemented."
Epidemiology of autism spectrum disorder in Portugal: prevalence, clinical characterization, and medical conditions
"The objective of this study was to estimate the
prevalence of autistic spectrum disorder (ASD) and identify its clinical
characterization, and medical conditions in a paediatric population in
Portugal. A school survey was conducted in elementary schools, targeting
332,808 school-aged children in the mainland and 10,910 in the Azores
islands. Referred children were directly assessed using the Diagnostic
and Statistical Manual of Mental Disorders (4th ed.), the Autism
Diagnostic Interview–Revised, and the Childhood Autism Rating Scale.
Clinical history and a laboratory investigation was performed. In
parallel, a systematic multi-source search of children known to have
autism was carried out in a restricted region. The global prevalence of
ASD per 10,000 was 9.2 in mainland, and 15.6 in the Azores, with
intriguing regional differences. A diversity of associated medical
conditions was documented in 20%, with an unexpectedly high rate of
mitochondrial respiratory chain disorders."
