Is transient global amnesia a risk factor for amnestic mild cognitive impairment?

Transient Global Amnesia (TGA) is a common condition of unknown aetiology characterised by the abrupt onset of severe anterograde amnesia, which lasts less than 24 hours. Some authors have suggested that subclinical impairment of memory functions may persist for much longer, but neuropsychological assessment lasting years after TGA attack has not been performed so far. The aim of this study was to evaluate long-term cognitive functions in patients with a previous TGA episode. Fifty-five patients underwent a standardised neuropsychological assessment after at least one-year from the TGA attack, and were compared with 80 age-matched controls. TGA patients showed worse performances on tests evaluating verbal and nonverbal long-term memory and attention, with comparable global cognitive functions. By applying current criteria for amnestic Mild Cognitive Impairment (MCI-a) on TGA subjects, a group consisting of 18/55 (32.7%) MCI-a subjects was identified. There was no association between the presence of MCI-a and demographic variables, vascular risk factors, years since the TGA episode, or ApoE genotype. This study demonstrates that TGA appears to be a relatively benign syndrome although objective memory deficits fulfilling MCI-a criteria persist over time, as detected by multidimensional neuropsychological tasks performed at long-term follow-up.