Going back to that original graph, and trying to make sense of it
Figure One: twin age peaks:
(this image may be copyright: it's from the linked open source paper above, but please don't reproduce without linking to the original paper and explaining it may be copyright).
I noticed the
adult peak is much more pronounced in women than men so sex differences again may play a role in the peaks as well as the relative differences after puberty. The second peak is mid-to-late thirties, possibly extending to early forties. That seems to be too late to be accounted for by childbirth and young children (with stress/sleep deprivation/constant exposure to bugs). The second peak seems to start building from the mid-twenties.
If you were coming at this from a biopsychosocia perspective, would you be able to explain the age peaks, especially the later adult one (the first one would presumably be explained by EBV, and an inappropriate response to it)? Is there something about women in their thirties that would lead to a particuar psychological response?
Ah,
@Jonathan Edwards beat me to it:
And of course the second bump for ME looks similar. I keep coming back to the idea that these are curves you get with complex biological regulatory systems that have a built in trade off between diversity and stability. Neither looks like a psychosocial curve at all. Surely a psychosocial curve would have some asymmetrical camel-like outline relating to specific rites of passage? OK so everyone agrees that MS is not psychosocial, but the same case ... ...
For that matter I'm not sure what the biological explanation is either, though maybe it's in some way related to whatever is driving the MS peak .
OK, so I mused, and didn't get very far, apart from noticing the second peak is much more pronounced in women. What is it about women in their late thirties that doesn't apply to men of similar age?
Early peak
2. The first disease does NOT look like EBV, it starts too early.
Looking at the data more closely, the peak childhood years, given that small differnces probablly aren't signifcant, are:
- boys 11-14, avg 12.5
- girls: 13-15 (arguably 13-18), mean 14 or more
while this
Scottish study shows mono/EBV cases peak age 18-19 (see
Figure 4.)
I think
@Jonathan Edwards might have a theory on this mismatch
.