Long-term memory in children with epilepsy

Abstract

Memory difficulties represent a common complaint in patients with epilepsy. These difficulties may refer to (i) a faster rate of forgetting of newly-learned materials over long delays relative to short delays (accelerated long-term forgetting; ALF) or (ii) autobiographical memory (ABM) difficulties, including deficits in recall of episodic (re-experiencing of personal events) and semantic (factual information) components. To date, ALF and ABM studies have largely focussed on adults. This thesis assesses ALF and ABM in children with temporal lobe epilepsy (TLE) and in those with idiopathic generalised epilepsy (IGE). ALF is assessed in 23 children with TLE, 20 with IGE and 58 similarly-matched controls. Participants completed a battery of tests, including a measure of verbal learning and recall after short (30-min) and long (7-day) delays. Relative to controls, children with TLE recalled fewer words at the 7-day delay compared with the 30-min delay. Age was also negatively correlated with word recall after short and long delays within the TLE group. Children with IGE recalled fewer words after a long, but not short, delay relative to controls. Moreover, greater epilepsy severity was associated with poorer 7-day recognition in the IGE group. ABM was assessed in 21 children with TLE, 18 with IGE and 42 healthy controls. Children with TLE recalled fewer episodic, but not semantic, details than controls. Unlike controls, episodic recall did not increase with age in the TLE group and was unrelated to epilepsy factors, such as side of seizure focus. Children with IGE recalled fewer episodic details than controls while earlier age of seizure onset was associated with poorer episodic recall. Our findings suggest that long-term memory consolidation may be disrupted by temporal lobe pathology or seizure focus and generalised seizures. Finally, long-term memory deficits may gradually emerge in children with TLE, as older children are more likely to present with these deficits.