Do we know the average time taken to get an ME diagnosis? If it's five years or something, that whole graph is going to be shunted five years sideways (especially for the adults, I suspect, who will perhaps be more likely to initially get written off as stress cases).
If social factors affect diagnosis of men and women differently and introduce more noise into the men's distribution, I wonder if that might account for the flatter peak.
Has anybody found a graph of hormone levels by age? I googled a bit but couldn't find one.
I tried a PubMed search with 'endocrine' and 'age' in the title.
I got this:
http://www.ncbi.nlm.nih.gov/pubmed/25460292
which says "Aging increases the risk of developing obesity, sarcopenia, osteoporosis, and, also, cardiovascular diseases. A reduction of both bone and muscle mass with a corresponding increase of fat mass and inflammation and hormonal imbalance in the elderly lead to and may synergistically increase cardiovascular diseases. "
this:
http://informahealthcare.com/doi/abs/10.3109/09513590.2012.705372
which looks at the variation of a range of hormones in women with age, two of which decrease from about age 25, if I've understood the abstract from a quick look (full text needs log-in/payment).
this (full text):
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3368374/
which says "In males, levels of testosterone decrease by 1% per year, and those of bioavailable testosterone by 2% per year from age 30 [16, 58, 59]. In women, testosterone levels drop rapidly from 20 to 45 years of age [60]."
"circulating GH levels decline progressively after 30 years of age at a rate of ~1% per year [84]. In aged men, daily GH secretion is 5- to 20-fold lower than that in young adults [85]. The age-dependent decline in GH secretion is secondary to a decrease in GHRH and to an increase in somatostatin secretion [86]."
this:
http://www.ncbi.nlm.nih.gov/pubmed/19938780 which is called 'Endocrine changes with advancing age' and is in German - do we have a German reader who can access the paper?
this:
http://www.clinchem.org/content/45/8/1369.full which is called 'The Endocrinology of Aging' but I can't find much from a quick look - may need to look at the referenced papers.
There are many more but I'm tired now.