Memory loss may be a natural part of ageing. Simple, treatable causes include stress, insomnia, alcohol or drug use, and side effects of prescribed medicines. More serious causes include dementia and physical conditions, such as B12 deficiency, thyroid disease, mental disorders (including depression, bipolar and schizophrenia), and brain diseases (including tumours, Parkinson’s, multiple sclerosis or Huntingdon’s).
There are other amnesia types. These include retrograde amnesia, where you lose existing memories. Or transient global amnesia (TGA), where you have sudden, temporary memory-loss episodes not attributable to neurological conditions, like epilepsy or stroke, which occurs in middle or older