title: The impact of intelligence on memory and executive functions of children with temporal lobe epilepsy: Methodological concerns with clinical relevance.
abstract: OBJECTIVE
  Patients with TLE are prone to have lower IQ scores than healthy controls. Nevertheless, the impact of IQ differences is not usually considered in studies that compared the cognitive functioning of children with and without epilepsy. This study aimed to determine the effect of using IQ as a covariate on memory and attentional/executive functions of children with TLE.
  
  
  METHODS
  Thirty-eight children and adolescents with TLE and 28 healthy controls paired as to age, gender, and sociodemographic factors were evaluated with a comprehensive neuropsychological battery for memory and executive functions. The authors conducted three analyses to verify the impact of IQ scores on the other cognitive domains. First, we compared performance on cognitive tests without controlling for IQ differences between groups. Second, we performed the same analyses, but we included IQ as a confounding factor. Finally, we evaluated the predictive value of IQ on cognitive functioning.
  
  
  RESULTS
  Although patients had IQ score in the normal range, they showed lower IQ scores than controls (p = 0.001). When we did not consider IQ in the analyses, patients had worse performance in verbal and visual memory (short and long-term), semantic memory, sustained, divided and selective attention, mental flexibility and mental tracking for semantic information. By using IQ as a covariate, patients showed worse performance only in verbal memory (long-term), semantic memory, sustained and divided attention and in mental flexibility. IQ was a predictor factor of verbal and visual memory (immediate and delayed), working memory, mental flexibility and mental tracking for semantic information.
  
  
  CONCLUSIONS
  Intelligence level had a significant impact on memory and executive functioning of children and adolescents with TLE without intellectual disability. This finding opens the discussion of whether IQ scores should be considered when interpreting the results of differences in cognitive performance of patients with epilepsy compared to healthy volunteers.
authors.affiliation: Laboratory of Psychiatric Neuroimaging (LIM-21), Department and Institute of Psychiatry, Faculty of Medicine, University of São Paulo, São Paulo, SP, Brazil; Center for Interdisciplinary Research on Applied Neurosciences (NAPNA), University of São Paulo, São Paulo, SP, Brazil. Electronic address: patriciarzezak@gmail.com.
authors.forename: Patricia
authors.initials: P
authors.lastname: Rzezak
authors.affiliation: Neurology Department, University of Campinas, Campinas, SP, Brazil.
authors.forename: Catarina A
authors.initials: CA
authors.lastname: Guimarães
authors.affiliation: Neurology Department, University of Campinas, Campinas, SP, Brazil.
authors.forename: Marilisa M
authors.initials: MM
authors.lastname: Guerreiro
authors.affiliation: Center for Interdisciplinary Research on Applied Neurosciences (NAPNA), University of São Paulo, São Paulo, SP, Brazil; Laboratory of Clinical Neurophysiology, Department of Psychiatry, University of Sao Paulo Medical School, São Paulo, SP, Brazil.
authors.forename: Kette D
authors.initials: KD
authors.lastname: Valente
mesh_terms: D000293:Adolescent; D001288:Attention; D016022:Case-Control Studies; D002648:Child; D004833:Epilepsy, Temporal Lobe / Q000523:psychology*; D056344:Executive Function; D005260:Female; D006801:Humans; D007360:Intelligence; D007361:Intelligence Tests; D008297:Male; D008570:Memory, Short-Term; D009483:Neuropsychological Tests; D011237:Predictive Value of Tests; D012016:Reference Values
keywords: Adolescents; Children; Executive functions; Intelligence; Memory; Temporal lobe epilepsy