Autism

Autism is a neurodevelopment disorder that affects about 1 out of every 150 individuals in the U.S.  It is characterized by impairments in social interaction, trouble with communication, and restrictive and repetitive behaviors.  Improvements in the condition are not common.  Studies show that the incidence of autism is increasing.  More and more parents are seeking alternative and “off-label” therapies.

Numerous single photon emission computed tomography (SPECT) and positron emission tomography (PET)* research studies have demonstrated hypoperfusion (decreased blood flow) to several areas of the brain, mostly to the temporal lobes.  In one study the decreased blood flow got worse the older the child became.86

* PET is a test that uses a special camera and a radioactive marker to look at organs in the body.

PET scans are often used to evaluate cancer, check blood flow, and/or see how organs are functioning.  PET scans are done to study the brain’s blood flow and metabolic activity in a wide range of conditions such as MS, ALS, stroke, etc.  They are also done to determine the amount of blood flow to the heart, and to determine the prevalence of damaged heart tissue.87

Area of Cerebral Hypoperfusion Clinical Correlation
Thalamus Repetitive, self-stimulatory and unusual behaviors
Temporal lobes Desire for sameness and social/communication disorders
Temporal lobes and amygdala Impairments in processing facial expressions and emotions
Fusiform gyrus Difficulty recognizing familiar faces
Wernicke’s and Brodmann’s areas Decreased language development and auditory processing problems
Temporal and frontal lobes Decreased IQ

The cause of cerebral hypoperfusion in autistic individuals is not known but may be associated with inflammation of the brain.  There is evidence of inflammatory cells around the blood vessels, which could be consistent with vasculitis (inflammation of the blood vessels) leading to diminished cerebral blood flow.  There is also evidence of an increased level of markers for lipid peroxidation causing vasoconstriction and platelet aggregation.

Treatment of inflammation might help restore normal blood flow.  Many inflammatory conditions such as lupus, Kawasaki disease and encephalitis are all characterized by cerebral hypoperfusion and anti-inflammatory medication can restore blood flow to normal in some of these conditions.  With inflammation also comes edema leading to more hypoxia.

HBOT possesses strong anti-inflammatory effects.  It inhibits neutrophils’ attachment to blood vessel walls and reduces leukocyte adherence.  It has been used for cerebral hypoperfusion including fetal alcohol syndrome, cerebral palsy, autism, closed head injury and stroke.

Notes
86Zhang,  211.
87 www.webmd.com/a-to-z-guides/positron-emission-tomography