I'm not sure I've used the right words there, but here goes...
I'm considerably less intelligent when I'm at the upper end of my swings than the lower. With the misery comes more acute awareness, the ability to connect more things in my mind, and faster. With the highs I am slower, have a more narrow spectrum of mental ability.
It affects my concentration span, my vocabulary, my ability to multitask, concentrate on difficult tasks...
Anyone else?