In cases of ME or CFS or probably Lyme there are cognitive issues. This is not a psychotic problem, its about low blood flow and low metabolism in the brain, with possibly neurological or immunological issues as well. Many of these patients have areas of the brain that are almost switched off. We interpret that sometimes as having a hole in the way we can thing ... some things are not there any more. This is usually completely reversible in theory, but in practice is very hard to do.