Apologies, this New Scientist article requires a subscription to read the complete article. Thankfully, I do have a subscription and so I shall summarise it 🙂 Research indicates that the mutation that causes HD also seems to increase intelligence in people under 20 years old. This information is casting some new light on how our brain develops in childhood - https://www.newscientist.com/article/mg26034663-700-mutation-behind-huntingtons-linked-to-higher-childhood-intelligence/