I like the idea to categorize everything, but this could be done with tags or another drop down.
Ideally everyone could be able to see the topic/post count for all the Boards, from the main forum page. To generate more traffic we can merge a lot of them in a way I'm not exactly sure of yet. Ideally a website is known for 2-4 primary, memorable forums/Boards. These main boards are the core of their brand. The rest are just there out of politeness and to fill the web page.
I know a couple other forums that merged smaller sub-forums into their larger parents. And I kind of feel "News" sub-forums can just share the press release in some sort of Brain Health or General Health board. It's tempting to keep a separate forum for supplements or group buy stuff, but that could be broken down into brain/general health too making 2x2 = 4 boards. That's getting out of hand. Nutrition, Lifestyle, Dental health can probably be lumped in one greater category, as can Aging Theories, Stem Cells, News Releases.
Being able to tell which forums are hottest and most traveled from the main page is an under-rated asset. As is condensing information into a few main feeds. What you lose in on-topic-ness you gain in solidarity and sheer traffic volume.