There is evidence linking genius and insanity. Scientists have found certain mental illnesses such as schizophrenia and bipolar disorder are found many times in highly creative and intelligent people.There have been many scientific studies that have confirmed the idea of a "mad genius." This creates a dilemia between treating the illness while not stifling the creativity and ideas.
I believe that all things in life can be related to each other especially in this case. In order for one to achieve borderline genius you would surely have your downfalls and that is where the insanity part comes in to play. If you don't believe me just research some of the great minds and you'll see.
Labels like "genius" and "insanity" are far too subjective to convincingly ascribe a connection between traits labeled as such. The word "genius" can describe anyone from Albert Einstein to Frieda Kahlo, and though may have been describe as "eccentric," neither are considered insane. As for insanity, mental illnesses are complex and varied, and they are often influenced as much by culture as by neurobiology. Thus, attempting to link two such vague and subjective attributes is futile.
Geniuses are often thought to be insane because they process information differently than most people. When people think of genius, one person who comes to mind is Albert Einstein. His portraits make him look crazy, but he was just crazy smart. Many insane people are extremely smart, but I would not say the two are connected. There are just as many dumb insane people.