BIO: Confusion in the extreme form of delirium is pathological. Engel, a psychiatrist, saw it as cerebral insufficiency. Though it has many causes, one significant trigger is inflammation, which is true of an increasing number of psychological disorders. The experience of delirium may arise from varieties of synaptopathy.
Less extreme are the everyday symptoms of brain fog, an informal category of confusion symptoms. A lot of people experience brain fog now and then from jet lag–of course- or sleep deprivation, systemic exertion intolerance disease (as chronic fatigue syndrome has been renamed), fibromyalgia, chemotherapy, low blood sugar, Lyme disease, menopause, or aerotoxic syndrome and some prescription medications. (Or missing medications like thyroid pills.) Aside from drugs, the list goes on in unscholarly avenues. A pregnant woman may ask if it’s normal to become so forgetful, which might be related more to fatigue than cognition. And chronic inflammation may lead to attentional lapses.