Advanced thinning roots

Hey guys. I joined here when I first started out dreading, and now my dreads are over a year and a half old.

I've noticed that some of my really thick dreads have extremely thin roots. I mean less than a millimeter thick. I brushed out the only "paddle" mat I ended up getting earlier today, which also had very thin roots, and when I got to the top it just broke off. I'm really scared now that my other dreads will end up doing the same thing.

I haven't done anything to them at all. I don't do any root maintenance or, actually, any maintenance at all.
If I crochet some loose hair into the top of the dread (where it's thicker) will it eventually join the roots?

updated by @niya-amity-haven: 01/13/15 10:01:14PM

are they visibly thinner or just feel thinner a 1 inch dread can feel 1 mm at the roots when pinched since the roots arent dreaded pinching it ca n flatten it to the width of a singl,e or few haitrs

chances are it just feels thinner the others maybe broke due to the combing?

can u post pics?

--
My new book Ban The Taboo Vol 1

They're visibly thinner. I think hair has actually come out of the dreads because there's a lot of short loose hair in the area.

I've attached a photo of one of the dreads in question. It does have a slightly thicker root than the others though.