A Study of the Association Between Autism and Immune Changes in the Brain

Current estimates indicate that 1 in 110 children are affected with autism. Despite this
striking statistic, we remain unable to describe the pathophysiology for autism, and we do
not have adequate treatments for autism. The etiologies in most patients with autism are
unknown, but emerging evidence supports a causal role of immune activation in autism.
Multiple studies provide clear evidence of immune activation in peripheral blood of patients
with autism, as demonstrated by elevations in immune markers (IFN-gamma, IL-1RA, IL-6, and
TNF-alpha). Studies also demonstrate immune activation in cerebrospinal fluid (CSF) of
patients with autism, as evidenced by significant elevations in cytokines and TNF-alpha.
Finally, three postmortem brain studies report neuroimmune activation in patients with
autism (ages 4-45). Combined, these three postmortem studies show activation of microglia
and astroglia through elevations in cytokines, histology and stereology.

While the growing body of literature supporting neuroimmune activation in autism is
intriguing, the current results present limitations. First, there are no studies assessing
the brains of living patients with autism/ASDs. Second, the most convincing evidence for
neuroimmune activation in postmortem brains is extracted almost exclusively from patients
with classical autism, where intellectual disability is common. As such, the evidence for
neuroimmune activation in higher functioning patients with autism and autism spectrum
disorders (ASDs) is less robust.

We propose to determine whether neuroimmune activation is present in the living brains of
patients with autism. Furthermore, given the heterogeneity of the autisms , as they are now
called, we would like to determine whether neuroimmune activation is detectable in higher
versus lower functioning patients with autism/ASDs. We propose to measure neuroimmune
activation in the living brains of patients by utilizing positron emission tomography (PET)
and the radioligand [(11)C]PBR28. This radioligand binds translocator protein (TSPO), which
is over-expressed in activated microglia and reactive astrocytes, and has been demonstrated
as a reliable marker of neuroimmune activation in various neuropsychiatric disorders.
Because the majority of patients with autism/ASD will require propofol sedation to remain
motionless for the two hour scan, we will include a control arm with healthy volunteers
without then with propofol in order to determine the effects of propofol on [(11)C]PBR28
uptake. NIH has developed a setup in the clinical center for administering
sedation/anesthesia in a safe manner, making this important study possible.

- INCLUSION CRITERIA:

PATIENTS WITH AUTISM OR ASD (INCLUSION CRITERIA):

1. Subjects must have a diagnosis of autistic disorder (299.0) or Asperger s disorder
(299.80), as determined using the Diagnostic and Statistical Manual-IV (DSM-IV) and
confirmation with the Autism Diagnostic Interview-Revised (Lord 1997) and/or Autism
Diagnostic Observation Scale (ADOS). (A diagnosis of Pervasive Developmental
Disorder, or PDD, will not suffice for this protocol).

2. Subjects must be adults between 18-45 years old.

3. Subjects must be healthy based on history and physical examination.

4. Subjects must be "binders" to [11C]PBR28 as determined via one of two ways: by prior
participation in a PET scan with [11C]PBR28 or by in vitro testing of their
leukocytes. We found that non-binders have markedly reduced affinity of [3H]PBR28 to
leukocyte membranes. The in vitro binding has shown no overlapping values between
binders (~90%) and non-binders.

5. Subjects must either provide informed consent, or they must assent in combination
with informed consent by a legal guardian or durable power of attorney (DPA).

HEALTHY VOLUNTEERS (INCLUSION CRITERIA):

1. Subjects must be adults between 18-45 years old.

2. Subjects must be healthy based on history and physical examination

3. Subjects must be binders to [11 C]PBR28 (see point 4 above for details)

4. Prior to the PET scan, all healthy subjects must have had within the prior year an
MRI scan of the brain to rule out significant structural abnormalities.

EXCLUSION CRITERIA:

PATIENTS WITH AUTISM OR ASD (EXCLUSION CRITERIA):

1. Any history of alcohol or substance dependence, as these conditions may alter uptake
of [11C]PBR28.

2. Any history of alcohol or substance abuse within the past 6 months, as these
conditions may alter uptake of [11C]PBR28.

3. Schizophrenia.

4. In addition to the diagnosis of autistic disorder, ASD or Asperger, any other Axis I
disorder that requires inpatient hospitalization during this study, or is at the time
of enrollment worsening relative to baseline. We will not completely exclude all Axis
I disorders, because it is typical for patients with autism /ASD to carry comorbid
Axis I disorders, including Generalized Anxiety Disorder (GAD), social phobia,
obsessive compulsive disorder (OCD), dysthymia, Major Depressive Disorder.

5. Intellectual quotient (IQ) less than 30, as including the lowest functioning patients
would make the experiment logistically challenging and would broaden heterogeneity
too much.

6. Clinically significant laboratory abnormalities as assessed by the PI, medically
responsible investigator or consultant.

7. Serious medical problems including but not limited to chronic neurological disease
such as multiple sclerosis, autoimmune diseases, poorly controlled seizure disorder,
or serious cardiopulmonary disease.

8. Active seizure disorder, as defined as having had a seizure in the past year or being
on antiepileptic medications for seizures.

9. Positive HIV status.

10. Head trauma resulting in a period of unconsciousness lasting longer than 5 minutes.

11. Exposure to radiation in the past year (i.e., PET from other research), which when
combined with this study would be above the allowable limits.

12. Positive urine drug screen at time of enrollment.

13. Pregnancy at time of scan (beta HCG will be measured in all female patients within 24
hours before start of scan and must be negative).

14. In patients who will get an MRI scan at NIH, metallic foreign bodies that would be
affected by the MRI magnet, or a fear of enclosed spaces that would prohibit MRI
scanning.

15. Allergy to propofol or eggs (since egg products are used to formulate propofol),.

16. Snoring, as this increases the likelihood of complications from propofol sedation.

17. Currently taking antibacterial drugs (such as Amoxicillin-Clavulanate/ Augmentin ,
Metronidazole/Flagyl Minocycline/Minocin ). We will not discontinue any medications
in any subjects.

18. Currently taking antiviral drugs (such as Acyclovir/Zovirax , Interferon beta
1/Avonex , Valacyclovir/Valtrex ). We will not discontinue any medications in any
subjects.

19. Taking corticosteroids within the 6 months prior to study enrollment (such as
Dexamethasone/Decadron , Hydrocortisone/Hydrocortone , Methylprednisone/Medrol ). We
will not discontinue any medications in any subjects.

20. Taking immunosuppressants in the past 6 months prior to study enrollment (such as
Azathioprine/Imuran , Infliximab/Remicade , Sulfasalazine/ Azulfidine ,
Olsalazine/Dipentum ). We will not discontinue any medications in any subjects.

21. Any history of taking immunosuppressants in the context of chemotherapy or organ
transplant. Medications in this class might include Tacrolimus/Prograf ,
6-mercaptopurine/Purinethol , and Methotrexate/Trexall . We will not discontinue any
medications in any subjects.

22. Currently taking Clozapine/Clozaril , as high doses in rats increases TSPO. With the
exception of clozapine, patients may be on centrally-acting medications, including
medications for mood and behavioral disturbances. These medications may be
antiepileptic medications, so long as the antiepileptics are being used for symptoms
of mood and behavior as opposed to seizure disorder.

Healthy Volunteers (Exclusion criteria):

1. Any past or present Axis I disorder. The exception is substance abuse which ended
over 6 months prior to enrollment.

2. Intellectual disability or significant learning problems, as determined by IQ testing
lower than 70, inability to read or write, or history of being unable to take regular
classes while in school.

3. Clinically significant laboratory abnormalities, as defined as laboratory values that
are out of normal range or require clinical workup and/or treatment.

4. With the exception of isolated doses of benzodiazepine which may be administered once
or twice by the investigators of this study, psychotropic medication use (including
benzodiazepines and illicit drugs) during the 28 days (42 days if fluoxetine) prior
to the PET scan. Investigators of this study may administer lorazepam for anxiety
(see procedures).

5. Serious medical problems including but not limited to chronic neurological disease
such as multiple sclerosis, autoimmune diseases or cardiopulmonary disease that would
significantly increase risk with propofol sedation.

6. Positive HIV status.

7. Metallic foreign bodies that would be affected by the MRI magnet or fear of enclosed
spaces likely to make the subject unable to undergo an MRI scan.

8. Head trauma resulting in a period of unconsciousness lasting longer than 5 minutes.

9. Exposure to radiation in the past year (i.e., PET from other research), which when
combined with this study would be above the allowable limits.

10. Positive urine drug screen at time of enrollment

11. Inability to lie flat on a camera bed for about 2.5 hours per PET scan and 1 hour for
MRI.

12. Allergy to propofol or eggs, since egg products are used to formulate propofol

13. Pregnancy at time of scan (beta HCG will be measured in all female patients within 24
hours prior to start of scan and must be negative).

14. Snoring, as this condition increases the likelihood of complications from propofol
sedation.

15. Currently taking antibacterial drugs (such as Amoxicillin-Clavulanate/ Augmentin ,
Metronidazole/Flagyl Minocycline/Minocin ). We will not discontinue any medications
in any subjects.

16. Currently taking antiviral drugs (such as Acyclovir/Zovirax , Interferon 1/Avonex ,
Valacyclovir/Valtrex ). We will not discontinue any medications in any subjects.

17. Taking corticosteroids within the 6 months prior to study enrollment (such as
Dexamethasone/Decadron , Hydrocortisone/Hydrocortone , Methylprednisone/Medrol ). We
will not discontinue any medications in any subjects.

18. Taking immunosuppressants in the past 6 months prior to study enrollment (such as
Azathioprine/Imuran , Infliximab/Remicade , Sulfasalazine/ Azulfidine ,
Olsalazine/Dipentum ). We will not discontinue any medications in any subjects.

19. Any history of taking immunosuppressants in the context of chemotherapy or organ
transplant. Medications in this class might include Tacrolimus/Prograf ,
6-mercaptopurine/Purinethol , and Methotrexate/Trexall . We will not discontinue any
medications in any subjects.