Problems with thinking clearly. While there may be a number of issues which can cause problems with thinking clearly, it could also be due to a Candida infection. When you’re suffering from an overgrowth of Candida albicans, this produces a toxin called acetaldehyde. If you have a serious Candida infection, your blood may literally be awash in acetaldehyde, and it may not be possible for your liver to process it all before some of it reaches your brain or your nervous system. Acetaldehyde can cause confusion in thinking, and can also prevent you from remembering things that would otherwise easily come to mind. It is also associated with an inability to concentrate. So, if you are experiencing any of the above symptoms, you might consider the possibility that you are suffering from a yeast infection.