Thyroid Functioning and Risk of Childhood Autism

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Thyroid Functioning and Risk of Childhood Autism

• Heather M. Barrow, M.P.H
• H. Patrick Stern, M.D.
• Tiejian Wu, M.D., Ph.D.

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Introduction

• Autism is a neurobiological disorder of a complex
  developmental disability that has to appear
  during the first 3 years of life.
• Individuals with autism have problems with social
  interaction, communication difficulties, and
  restrictive or repetitive interests/behaviors.

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Introduction

• Recent studies by the National Institute of
  Health
• One out of 250 children born in the United States
  has some degree of autism.
• The risk increases to about one in 25 if the
  child has a brother or sister with the condition.
  
• It is generally accepted that autism includes
  abnormalities in the brain structure or
  physiological function, while the causes for the
  abnormalities are not clear.

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Introduction

• Abnormal thyroid function can have a variety of
  behavioral effects, ranging from severe
  neuropsychological defects in children with
  congenital hypothyroidism to hyperactivity
  associated with hyperthyroidism.
• The purpose of this study is to examine the
  association between thyroid function and risk of
  childhood autism.
• If there is an association, this will allow for
  the possible consideration of a therapeutic
  treatment of thyroid.

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Review of the Literature

• There have been a few studies that have examined
  the relationship between thyroid hormone and
  autism status.
• A study conducted in 1980 by Cohen et al.
  evaluated the blood indices of thyroid function,
  including T4, T3, and TSH, in a larger population
  of autistic children.
• No differences were found between autistic and
  normal children.
• Another study conducted by Hashimoto et al. in
  1991 showed that mean TSH basal levels, mean TSH
  peak levels, and mean TSH peak values minus basal
  values were significantly lower in autistic
  children than in the control group.

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Review of the Literature

• One study that has recently investigated the
  relationship between neonatal measure of thyroid
  and autism in children.
• This study conducted by Soldin et al. in 2003
  found that there were no significant differences
  that were detected between neonatal (T4) values
  in the cases of autistic spectrum disorder and
  the controls.
• All neonatal T4 values were within normal ranges.
  

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Summary

• There is a biological possibility that thyroid
  hormone may play a role in the development of
  autism.
• There is no consistency amongst these few studies
  on whether or not there is a relationship between
  thyroid hormone and autism status.
• Further investigation needs to be done in order
  to see if there is a possible relationship
  between thyroid hormone and autism.

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Methods

• Community Care Wellness Center
• The parents of 88 children diagnosed with autism
  were contacted by mail and phone.
• Packets-cover letter and informed consent form
• Phone-an initial and a follow-up phone call
• Medical charts were reviewed.
• Chart review - Parent questionnaire
• Lab tests-Current TSH, T4, Free T4, T3, Free T3,
  Lead, Ferritin, and Genetics
• Collect neonatal TSH levels from the Tennessee
  neonatal screening program.

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Methods

• A database was created to sort the 88 patients
  into categories.
• 70 of the parents were contacted by phone.
• 18 phone numbers were disconnected
• 3 of the addresses were wrong
• 10 participants refused to participate

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Methods

• Number of eligible patients 57 (age range of 1-
  15 years old).
• 23 (40) informed consents were received
• The lab results were tabulated in a spreadsheet
  in relation to specific reference values.

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• Results

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Discussion

• This pilot study was able to observe several
  trends from the collected data.
• Current TSH levels tended to be on the lower end
  of the normal range
• More data is needed to show the patterns of T3
  and T4.
• This may indicate that thyroid hormone may play a
  role in the risk of childhood autism and deserves
  further research attention.

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Discussion

• This study has several limitations.
• Small sample size of only 23
• All study subjects are males
• Only 7 of the eligible 57 patients were female.
• Normal range was used, but a control group was
  not available.
• Not all of the patients had all of the lab
  results
• This study was not able to retrieve the neonatal
  thyroid levels at this time.
• These levels will be retrieved at a later date in
  order for this study to be complete.

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Conclusion

• This pilot data indicates that there could be a
  possible correlation with thyroid functioning and
  risk of childhood autistic spectrum disorder.
• A better understanding of autism will help in
  better prevention and treatment strategies.
• Further investigation is needed in order to
  better understand the etiology of autism.