Here's a link to an article in PubMed Central that reviews research on pharmacological treatments with individuals with ASD; clonidine is mentioned.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3338180/

And one in PubMed Central that looks at guanfacine:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2835389/

Maybe they will lead you to some other helpful references.

Linda

Hagerman e.a. (2009), and see link, mention both guanfacine and clonidine for ADHD symptoms in FXS (and ASD).

http://pediatrics.aappublications.org/content/123/1/378.full.html

Yeah they are more to control the ADHD/ODD stuff that is generally coupled with the Autism diagnosis. They lower blood pressure to adjust for the hyperactive symptoms.

Guanfacine (brand name Tenex, and the extended release Intuniv) and Clonidine (trade name Kapvay or Nexiclon) are selective a-2 agonists. These medications are mainly used to treat high blood pressure. Oral or transdermal administration of selective a-2 agonists have shown improvement in autistic individuals. It has been shown that guanfacine gives improvements in attention, hyperactivity, insomnia, and tics (Posey et al. 2004). The most common adverse effects observed with guanfacine are insomnia, fatigue, blurred vision, headache, and mood alteration (Boellner et al. 2007). Clonidine improves hyperactivity, mood instability, aggressiveness and agitation in autistic individuals. The side effects of this medication are mostly acceptable. Fankhauser and coworkers (1992) did a placebo-controlled double-blind clinical trial of clonidine in autism. The study provides evidences for the clinical efficacy and safety of clonidine in autism and related disorders. A newer study shows that Clonidine (at bedtime) also produced improvements in sleep, night time awakenings, aggression and mood (Ming et al. 2008). You will find further relevant studies on these drugs by searching medical databases.

REFERENCES

Boellner SW, Pennick M, Fiske K, Lyne A, Shojaei A (2007) Pharmacokinetics of a guanfacine extended-release formulation in children and adolescents with attentiondeficit-hyperactivity disorder. Pharmacotherapy 2007; 27: 1253-62.

Fankhauser MP, Karumanchi VC, German ML, Yates A, Karumanchi SD (1992) A double-blind, placebo-controlled study of the efficacy of transdermal clonidine in autism. J Clin Psychiatry 1992; 53: 77–82.

Ming X, Gordon E, Kang N, Wagner GC (2008) Use of clonidine in children with autism spectrum disorders. Brain Dev 30: 454–60.

Posey DJ, Puntney JI, Sasher TM, Kem DL, McDougle CJ (2004) Guanfacine treatment of hyperactivity and inattention in pervasive developmental disorders: a retrospective analysis of 80 cases. J Child Adolesc Psychopharmacol 14; 233-41.

Just a side note. We tried to My daughter with autism off risperdal and onto Tenex transdermal patches (Guanfacine) and it made her zombie like, agitated, she stopped answering intraverbals, stopped giving hugs and socializing with the family, It was horrible. She was a different kid.

References

Arnsten, A. F., & Jin, L. E. (2012). Guanfacine for the treatment of cognitive disorders: A century of discoveries at Yale. The Yale journal of biology and medicine, 85(1), 45.

Masana, M., Santana, N., Artigas, F., & Bortolozzi, A. (2012). Dopamine Neurotransmission and Atypical Antipsychotics in Prefrontal Cortex: A Critical Review. Current topics in medicinal chemistry, 12(21), 2357-2374.

Handen, B. L., Sahl, R., & Hardan, A. Y. (2008). Guanfacine in children with autism and/or intellectual disabilities. Journal of Developmental & Behavioral Pediatrics, 29(4), 303-308.

Tsai, L. Y. (1999). Psychopharmacology in autism. Psychosomatic medicine, 61(5), 651-665.

Scahill, L., Aman, M. G., McDougle, C. J., McCracken, J. T., Tierney, E., Dziura, J., ... & Vitiello, B. (2006). AProspective Open Trial of Guanfacine in Children with Pervasive Developmental Disorders. Journal of Child & Adolescent Psychopharmacology, 16(5), 589-598.

Guanfacine or its slow release form has recently been approved for the treatment of ADHD in children and adults, but I'm not aware of similar recommendations for ASD by the FDA. I would not be surprised that the beneficial effects reported in clinical trials are mixed for ASD, since it is a heterogeneous condition. GUAN and clonidine seem to provide the best clinical outcomes when catecholamine frontal circuits are compromised. The work of Dr. Amy Arnsten from Yale illustrates this point very well.

See my answer above about autism. It exists better documentation for the use of selective alpha-2 agonists in ADHD than autism. It is a need for further research.

i agree Geir - there seems to be a research gap there. I wounder if there is any evidence suggesting "pro-social" effects of GUAN or CLO in humans?