"A possible implication is that interventions aimed at either autism symptoms or symptoms of depression may improve the other."
That was the intriguing statement made by Per Normann Andersen and colleagues  who "investigated the course of and association among changes in autism symptoms, depression symptoms and executive functions (EF) in children with high-functioning autism (HFA)." Aside from frowning a little at the mention of the concept of 'high-functioning' I assume to denote those who have "relatively mild symptoms which, despite their mildness, are significant enough to merit an autism spectrum diagnosis" according to one description (see here), I was interesting in the Andersen findings. Specifically, the idea that the spectrum of depression (depressive illness if you will) might be something rather more integral to the presentation of autism at least for some people.
I've talked before about depression as one of several mental health issues/problems perhaps over-represented following a diagnosis of autism (see here). The paper by Vannucchi and colleagues  covered in a previous post (see here) did particularly well bringing into sharp focus the fact that bipolar disorder may very well be a frequent comorbidity in cases of Asperger syndrome albeit "often characterized by atypical presentation, making its correct identification particularly difficult."
Of course this is not the first time that something of a rather intimate relationship has been reported when considering depression and autism together. Takara & Kondo  (open-access) reported that: "Depressed adults with comorbid atypical autistic traits are at higher risk for suicide attempts and may engage in methods that are more lethal" based on their case-control study. This is perhaps one of the more extreme outcomes potentially associated with depression but also highlights something of a growing realisation that suicide ideation may not be an uncommon issues reported by some on the autism spectrum (see here) and may to some extent tie into the presentation of depression.
Further work is required to better categorise depression comorbid to a diagnosis on the autism spectrum as per the the findings from Gotham and colleagues . Additional work is also required on the best way(s) to tackle depression in cases of autism whether based on pharmacotherapy or other more psychological approaches. I might also advance the case that several other potentially important variables be also examined, such as vitamin D (see here) in light of the evidence related to autism in this area and the various anti-inflammatory strategies (see here) also tentatively put forward as management options for depression. Inflammation and autism, as some readers might know, is a topic in the research ascendancy (see here). There may be other areas slightly outside of the mainstream that might also be considered as research targets too.
Without any medical advice given or intended, I'm also going to link you to the case study (stress: case study) presented by Philip Bird  (open-access) talking about the use of the anti-epileptic phenytoin with a young man with autism. Aside from some interesting positive effects recorded on autism presentation, Bird also noted that: "Post-treatment, there was robust change in all domains, with an absence of depressive symptoms and with both anxiety and stress being recorded as moderate." I'm not saying that this will be for everyone (personalised medicine and all that). Merely that there may be many different ways of tackling such issues when combined and some thinking 'outside of the box' might be required.
The next questions: how does depression combine with something like anxiety with autism in mind, and what happens to depressive and other symptoms when anxiety is 'treated'? Further, given the connection between depression and other diagnoses such as schizophrenia  and acknowledging that a diagnosis of autism is seemingly not protective against developing schizophrenia (see here), are there other lessons that could be learned about the relationship(s) between various diagnostic labels?
More research is indicated...
So: Black Grape - Reverend Black Grape.
 Andersen PN. et al. Associations Among Symptoms of Autism, Symptoms of Depression and Executive Functions in Children with High-Functioning Autism: A 2 Year Follow-Up Study. J Autism Dev Disord. 2015 Mar 13.
 Vannucchi G. et al. Bipolar disorder in adults with Asperger׳s Syndrome: A systematic review. J Affect Disord. 2014 Jul 8;168C:151-160.
 Takara K. & Kondo T. Comorbid atypical autistic traits as a potential risk factor for suicide attempts among adult depressed patients: a case-control study. Ann Gen Psychiatry. 2014 Oct 16;13(1):33.
 Gotham K. et al. Depression and its measurement in verbal adolescents and adults with autism spectrum disorder. Autism. 2014 Jun 10. pii: 1362361314536625.
 Bird PD. The treatment of autism with low-dose phenytoin: a case report. J Med Case Rep. 2015 Jan 16;9:8.
Andersen PN, Skogli EW, Hovik KT, Egeland J, & Øie M (2015). Associations Among Symptoms of Autism, Symptoms of Depression and Executive Functions in Children with High-Functioning Autism: A 2 Year Follow-Up Study. Journal of autism and developmental disorders PMID: 25763986