Hyperuricemia is an excess of uric acid in the blood. Uric acid passes through the liver, and enters your bloodstream. Most of it is excreted (removed from your body) in your urine, or passes through your intestines to regulate "normal" levels. Uric acid highly affects the development of human brain. It therefore appears that the IQ of a person could be predicted by finding out his serum uric acid value. A positive correlation was found in serum uric acid levels and IQ.
There is much evidence concerning the positive role of hyperuricemia regarding the CNS (in contrast to its negative influence on the metabolic processes in diabetes, metabolic syndrome, hypertension etc.). The geneticist V.P. Efroimson analyzed hundreds of the historical personalities in the verified sources and established at least tenfold increase in the frequency of gout among eminent personalities (and a great part of his book "Genetics of Genius" is devoted just to hyperuricemia). It is highly possible that uric acid effect is directed not on IQ itself, but on the general activity of the person allowing to realize the existing abilities to the maximum extent.
Much verified data has appeared recently, like the works cited by Entedhar Sarhat. Besides, there is a neuroprotective effect of uric acid partially linked to its antioxidant effect which is especially high just within the brain, and the results appear about its positive influence in neurodegenerative diseases.
Several years ago we tried to summarize such data in the review, I can send you a copy if there is an interest.