"Anxiety disorders significantly increased mortality risk. Comorbidity of anxiety disorders and depression played an important part in the increased mortality."
So said the findings reported by Sandra Meier and colleagues  looking to assess any relationship between the presence of an anxiety disorder and mortality risk. Based on data from one of those oh-so-useful Scandinavian population registries (Denmark this time), researchers reported that: "The risk of death by natural and unnatural causes was significantly higher among individuals with anxiety disorders... compared with the general population." Death by unnatural causes was also linked in quite a few cases to "comorbid diagnoses of depression."
Although making sombre reading, the data from Meier et al provide further evidence  that a psychiatric/behavioural diagnosis might have far-reaching implications when it comes to the risk of early mortality, be that based on natural causes or something rather more unnatural such as death by suicide or an enhanced risk of accidental death or death because of illness. This also follows a trend suggesting that severe mental illness also has social implications such as an increased risk of becoming a victim of crime too (see here). Quality of life, health-related or otherwise, is nearly always affected by such diagnoses.
I introduced the 'implications for autism' bit to this post simply because (a) when it comes to comorbidity surrounding the diagnosis of autism, anxiety and depression (various types) pretty much come top with regards to psychiatric labels applied (see here and see here respectively) and (b) enhanced risk of early mortality is also an unfortunate feature when it comes to autism too (see here). Putting these findings together and well, I'm sure you can understand the need for quite a bit more study in this area and in particular, a reiteration of how utterly disabling anxiety and/or depression can be when it comes to autism.
If and when possible roles for anxiety and/or depression are found to contribute to some of the excess risk of early mortality when it comes to autism, the bright side is that this could have implications for intervention and management and onwards a reduction in mortality risk. I might also introduce the findings reported by Butnoriene and colleagues  at this point, who suggested that sex differences might also be relevant to the type of risk factors associated with mortality. Discussions in this area should also probably include discussions on a related topic based on a particularly extreme path being selected by some on the autism spectrum (see here).
Without trying to make connections where none might exist, I'm also inclined to suggest that outside of psychological and pharmacological interventions to tackle anxiety and/or depression comorbid to autism, one might also look to treating certain somatic correlates also potentially exerting an effect (see here). There is potentially lots to examine across such comorbidities as yet again, another very important line of study opens up that intersects with autism.
Finally, dare I also add that other labels such as obsessive-compulsive disorder (OCD) that may also intersect with some autism (see here - yes, this is another Meier paper) might also increase the risk of early mortality when it comes to autism too ?
 Meier SM. et al. Increased mortality among people with anxiety disorders: total population study. The British Journal of Psychiatry. 2016; 209: 216-221.
 Pratt LA. et al. Excess mortality due to depression and anxiety in the United States: results from a nationally representative survey. Gen Hosp Psychiatry. 2016 Mar-Apr;39:39-45.
 Butnoriene J. et al. Metabolic syndrome, major depression, generalized anxiety disorder, and ten-year all-cause and cardiovascular mortality in middle aged and elderly patients. Int J Cardiol. 2015;190:360-6.
 Fernández de la Cruz L. et al. Suicide in obsessive-compulsive disorder: a population-based study of 36 788 Swedish patients. Mol Psychiatry. 2016 Jul 19.
Meier SM, Mattheisen M, Mors O, Mortensen PB, Laursen TM, & Penninx BW (2016). Increased mortality among people with anxiety disorders: total population study. The British journal of psychiatry : the journal of mental science PMID: 27388572