The International Journal of Neuropsychopharmacology

Brief Report

Effect of fluoxetine on regional cerebral metabolism in autistic spectrum disorders: a pilot study

Monte S.  Buchsbaum  a1 c1, Eric  Hollander  a1, M.  Mehmet Haznedar  a1, Cheuk  Tang  a1, Jacqueline  Spiegel-Cohen  a1, Tse-Chung  Wei  a1, Andrea  Solimando  a1, Bradley R.  Buchsbaum  a1, Diana  Robins  a1, Carol  Bienstock  a1, Charles  Cartwright  a1 and Serge  Mosovich  a1
a1 Neuroscience PET Laboratory, Mt. Sinai School of Medicine, New York, USA


The regional metabolic effects of fluoxetine were examined in patients with autism spectrum disorders. Six adult patients with DSM-IV and Autism Diagnostic Interview (ADI) diagnoses of autism (n = 5) and Asperger's syndrome (n = 1), entered a 16-wk placebo-controlled cross-over trial of fluoxetine. The patients received 18F-deoxyglucose positron emission tomography with co-registered magnetic resonance imaging at baseline and at the end of the period of fluoxetine administration. After treatment, the patients showed significant improvement on the scores of the Yale–Brown Obsessive–Compulsive Scale – Obsessions subscale and the Hamilton Anxiety Scale; Clinical Global Impressions – Autism scores showed 3 of the patients much improved and 3 unchanged. Relative metabolic rates were significantly higher in the right frontal lobe following fluoxetine, especially in the anterior cingulate gyrus and the orbitofrontal cortex. Patients with higher metabolic rates in the medial frontal region and anterior cingulate when unmedicated were more likely to respond favourably to fluoxetine. These results are consistent with those in depression indicating that higher cingulate gyrus metabolic rates at baseline predict SRI response.

(Received June 18 2000)
(Reviewed September 13 2000)
(Revised December 4 2000)
(Accepted December 18 2000)

Key Words: Positron emission tomography; magnetic resonance imaging; selective serotonin reuptake inhibitor; cingulate gyrus; orbitofrontal cortex; autism; Asperger's syndrome.

c1 Address for correspondence: Dr M. S. Buchsbaum, Neuroscience PET Laboratory, Box 1505, Mt. Sinai School of Medicine, One Gustave L. Levy Place, New York, NY 10029-6574, USA. Tel.: +1 212 241-5294 Fax: +1 212 423-0819 E-mail: