Accelerated forgetting in patients with epilepsy - Evidence for an impairment in memory consolidation

Patients with epilepsy frequently complain of memory difficulties yet perfo rm normally on standard neuropsychological tests of memory. It has been sug gested that this may be due to an impairment of very long-term memory conso lidation processes, beyond those normally assessed in the neuropsychologica l clinic. We carried out a prospective study of verbal memory over a long-t erm retention interval of 8 weeks in patients with epilepsy and in controls . Results were compared with performance on conventional tests of memory. D espite normal learning and retention over 30 min, patients with epileptic f oci in the left temporal lobe performed disproportionately poorly on the lo ng-term test compared with both patients with epileptic foci in the right t emporal lobe and controls. Our findings provide evidence for an extended pe riod of memory consolidation and point to the critical region for this proc ess, at least for verbal material, in the left temporal lobe, The implicati ons of our findings for clinical assessment and therapeutic management of p atients with epilepsy are discussed.