Extended retention intervals can help to bridge the gap between subjective and objective memory impairment
Introduction from Dr Markus Reuber, editor-in-chief of Seizure
Memory problems are probably the most frequently reported problem in seizure clinics – almost on a par with seizures! People with epilepsy may report problems with prospective memory (eg. remembering to carry out planned activities), autobiographical memory or accelerated forgetting (remembering things well over some hours but forgetting them over days or weeks).
There are many reasons why people with epilepsy may experience memory difficulties, including structural abnormalities of memory-relevant parts of the brain, functional disruption of memory encoding, storage or retrieval processes by epileptic activity or antiepileptic drug toxicity or iatrogenic effects of epilepsy surgery. All this produces a level of complexity which makes memory complaints associated with epilepsy hard to study and understand.
This situation is made worse by the fact that patients themselves and experts (such as neuropsychologists) often fail to agree whether memory problems are actually present. Conventional memory tests may reveal no problems although patients complain bitterly about their memory.
Up to now, the level of depression or anxiety was the best explanation for this difference between “subjective” and “objective” memory performance. The carefully constructed study by Witt et al. published in this issue of Seizure identifies another relevant explanatory factor missed during conventional memory tests: the observation of accelerated forgetting (ALF). Tests for ALF require the examiner to contact the patient again several weeks after the exposure to the stimuli (for instance the word lists) patients were meant to remember. This means that it is a bit of a challenge to integrate them into routine test batteries applied in neuropsychology clinics. However, the paper by Witt et al. (and the accompanying brief review by Muhlert and Zeman) suggest that such tests should be used more widely if neurologists want to get a better understanding of one of their patients’ greatest concerns – perhaps not only in patients with epilepsy.