Abstracts

Rationale: It is well known that epilepsy clinical variables impact cognitive functioning of patients with Temporal Lobe Epilepsy (TLE). It is reasonable to believe that the course of epilepsy and being exposed to a longer duration of epilepsy activity may impact cognition differently when considering chronological age of the patient, even in adulthood. The aim of this study is to compare the impact of clinical epilepsy variables in episodic memory abilities of young and late adults with TLE.  Methods: Eighty-four patients with TLE caused by hippocampal sclerosis (TLE-HS) were evaluated with a cognitive battery for episodic memory functions. Patients were divided into two groups according to their age: young adulthood (n=41, age<=40 yo), and late adulthood (n=40, age>40 yo). Their raw score in the memory tests were converted into Z scores based on a reference control sample of 76 healthy participants also divided into two groups based on the same age criteria. The following clinical epilepsy variables were entered in a linear regression model with memory tasks as dependents variables for each age group separately: lesion lateralization, age of onset, duration, previous history of febrile seizures, previous history of status epilepticus, number of AEDs, history of bilateral generalized tonic-clonic seizures , seizure frequency and seizure control. Results: The two groups of patients had similar gender (x2=1.00, p=0.318), IQ scores (t=1.52; p=0.134), and schooling (t=0.77;p=0.442). As expected by group categorization criteria, they had different age (t=12.48; p<0.001). As to epilepsy variables, older patients had longer epilepsy duration (t=3.00; p<0.004) and earlier age of epilepsy onset (t=4.28; p<0.001). Patients had similar TLE-HS lateralization distributions, history of febrile seizures, type of seizure, seizure frequency and seizure control In the late adulthood group, delayed verbal memory was negatively impacted by lesion lateralization (p=0.028) and seizure frequency (p=0.020), while delayed recall of verbal learning was negatively impacted by lesion lateralization (p=0.016), age of onset (p=0.018), duration (p=0.018), febrile seizure (p=0.015), polypharmacy (p=0.008), bilateral generalized tonic-clonic seizures (p=0.016), seizure frequency (p=0.007), and seizure control (p=0.006). For young adults, there was not any significant impact of clinical epilepsy variables in memory tests.  Conclusions: Our findings showed a more pronounced negative impact of clinical epilepsy variables into memory functions of older patients with TLE-HS when compared to the younger group. Delayed recall of verbal material was impacted by variables related to structural lesion, duration of the brain functioning disorder, and with variables associated to disorder severity only in the group of older patients. Younger patients also had worse performance in memory tests than healthy controls but this cognitive functioning was somehow less influenced by epilepsy clinical variables.  Funding: FAPESP (grant numbers 13/11361-4; 12/09025-3; 12/13065-0), CNPQ (grant numbers 307262/2011-1; 476250/2013-7; 466995/2014)