This may sound entirely irrelevant but certain common diseases that usually show up around middle age cause brain fog, which we usually incorrectly diagnose as

This may sound entirely irrelevant but certain common diseases that usually show up around middle age cause brain fog, which we usually incorrectly diagnose as "aging". Diabetes is one such disease which highly decreases focus and energy on most people. Luckily, once managed, those effects mostly disappear. In my case, it was allergies. I discovered that I had gluten allergy (mild) since birth that somehow stayed out of my radar for 28 years. Only after age 28, its side-effects became so apparent that I had to take action, only to find out that it was there all the time.