Why it is done this way
Reversible causes get excluded before anything is diagnosed
Patients arrive frightened, having decided this is early dementia. Usually it is not.
Thyroid disease, B12 deficiency, low vitamin D, poor blood sugar control, sleep apnoea, hormone change and several very common prescriptions all produce exactly these symptoms.
Adult ADHD is also real and frequently undiagnosed. Both deserve a workup rather than a shrug.