The quote titling this post - "Ruminative thinking is the autistic dimension more strongly associated with suicidality" - comes from the findings published by Liliana Dell'Osso and colleagues  and provides something of an extension of previous work from authors on this paper (see here).
The important topic under investigation by Dell'Osso et al was suicidality; something that crops up time and time again in connection to the autism spectrum (see here). No, such a topic doesn't make for great PR 'about autism'. But if you want to talk about research/clinical priorities when it comes to the autism spectrum, I can't think of many topics that would be more pressing...
The hypothesis: those with subthreshold autistic traits (AT) and autism spectrum disorder (ASD) "will both show a higher prevalence of suicidal ideation and behaviors" when compared with asymptomatic controls. Further: "to clarify if AT do actually imply a risk factor for suicidality similar to full-blown ASD, hypothesizing that suicidal thoughts and behaviors will not differ between subjects with subthreshold autism and full-blown ASD." Similar sentiments have been previously expressed in other research results (see here and see here and see here).
I won't bore you with all the details of the hows-and-whys of Dell'Osso study (it is open-access) but do want to focus in on a few important observations made. First authors reported that they "found no differences in suicidality scores between ASD and AT groups, while both showed a higher score than HC [healthy controls]." I might add that 'HC' is a term used by the authors and wouldn't be my choice for describing a control group. This finding is important not just for autism but potentially for lots of other labels that manifest autistic traits (see here and see here) on the basis that autistic traits are not necessarily exclusive to a diagnosis of autism.
Second: "the ASD group reported significantly higher MOODS-SR total score and MOODS-SR depressive component score than the AT group, and the AT group in turn scored significantly higher than the HC." I don't think anyone should be really surprised by the finding that the symptoms of mood disorders such as depression seem to be 'over-represented' alongside a diagnosis of autism given other data on this issue (see here). Indeed, one might even say that depression could, for some autistic people, be considered a core issue over and above just being described as a comorbidity (see here).
Finally I head back to the title of this post, and how something like ruminative thinking - "a pattern of repetitive thinking, usually associated to and exacerbating anxiety and depression, often affecting problem-solving and the processing of negative feelings and leading to social isolation" - might be a particular dimension *associated* with suicidality in the context of autism or the presentation of subthreshold autistic traits. I've talked a few times about rumination in the context of autism on this blog (see here and see here). Rumination has also been talked about in the context of autism and suicide before too (see here). If research continues to point to rumination as something important, one might potentially envisage the development of interventions that could ameliorate such an issue and possibly onward *affect* the risk of something like suicidality?
I don't want anyone to get the impression that the Dell'Osso findings have *solved* the issue of suicidality in the context of autism because they haven't. As I've said many times before on this blog, suicide is a very, very complicated and deeply personal issue (see here) with no one-size-fits-all answer to the questions it raises. As part of a larger picture however, the Dell'Osso results are however important. If their application in a clinical context saves even one life, I would consider that to be infinitely worthwhile.
If anyone needs someone to talk to, there are people who will listen (see here and see here)...
 Dell'Osso L. et al. Mood symptoms and suicidality across the autism spectrum. Comprehensive Psychiatry. 2019. April 3.