I have written about my experiences here on the board. I cannot find an appropriate reference at this moment. I did search back and find this post that you might consider. viewtopic.php?f=7&t=6238&p=43878#p43878
Briefly my experience has been with someone with OCD and my own, what I now consider to be, perseveration of thought related possibly to high functioning Asperger's syndrome for which I have never been diagnosed. I now see that my own perseveration of thought was not the same as OCD and has been helpful in keeping me on the track of my purpose for being in this particular life. I do not know the answer to the question I posed in the post linked to above. I am inclining towards thinking that it is natural within our digital consciousness for a track of repeating obsession cycling at a very high rate. I can see this being picked out of our total thought stream as the focus item to be placed into our much slower moving PMR consciousness. I suspect that meditation could help, including asking for help to block the OCD stream to permit the meditation. I achieved earlier control of perseveration by repeatedly trying to do this myself and eventually succeeding. I was a child and knew nothing of meditation.
It is perhaps what your brother needs to work on in this lifetime as a reduction of entropy measure or it is perhaps a glitch of the VRRE aspect of TBC. Either way, persistent meditation might be helpful in my opinion.