He was shot in 1918 leaving bullets in his body and left him weakened, then in 1922 he suffered at least three debilitating strokes. He lost his ability so speak and had to learn to speak again. He even proposed assisted suicide because he was suffering so much. He then had a final fatal stroke in 1924. I don't think "he looks crazy so he must have had some STD" is medically accurate or remotely appropriate on what's supposed to be an academic forum. He most likely had brain damage towards the end thus his illness of course was reflected on his body looked. Lenin's eyes reflected his post-stroke damage.
He was quite sane in his life and his work expanding on Marx is of course extremely important.
