Thanks for the concern, I don't think I suffer from any health issues. Are there any notable health problems that you know of which have such psychological effects?

I am not a doctor but... Cognitive issues could be stress/burnout related. Environment can also play a big part in cognitive issues. Mold illness causes cognitive/psychological issues and patients often describe the feeling as a "brain-fog". There is a relatively simple online test for mold issues found here http://www.survivingmold.com/diagnosis.