title: Two distinct symptom-based phenotypes of depression in epilepsy yield specific clinical and etiological insights.
abstract: Depression is common but underdiagnosed in epilepsy. A quarter of patients meet criteria for a depressive disorder, yet few receive active treatment. We hypothesize that the presentation of depression is less recognizable in epilepsy because the symptoms are heterogeneous and often incorrectly attributed to the secondary effects of seizures or medication. Extending the ILAE's new phenomenological approach to classification of the epilepsies to include psychiatric comorbidity, we use data-driven profiling of the symptoms of depression to perform a preliminary investigation of whether there is a distinctive symptom-based phenotype of depression in epilepsy that could facilitate its recognition in the neurology clinic. The psychiatric and neuropsychological functioning of 91 patients with focal epilepsy was compared with that of 77 healthy controls (N=168). Cluster analysis of current depressive symptoms identified three clusters: one comprising nondepressed patients and two symptom-based phenotypes of depression. The 'Cognitive' phenotype (base rate=17%) was characterized by symptoms taking the form of self-critical cognitions and dysphoria and was accompanied by pervasive memory deficits. The 'Somatic' phenotype (7%) was characterized by vegetative depressive symptoms and anhedonia and was accompanied by greater anxiety. It is hoped that identification of the features of these two phenotypes will ultimately facilitate improved detection and diagnosis of depression in patients with epilepsy and thereby lead to appropriate and timely treatment, to the benefit of patient wellbeing and the potential efficacy of treatment of the seizure disorder. This article is part of a Special Issue entitled "The new approach to classification: Rethinking cognition and behavior in epilepsy".
authors.affiliation: Melbourne School of Psychological Sciences, The University of Melbourne, Victoria 3010, Australia; The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne Brain Centre, 245 Burgundy Street, Heidelberg, Victoria 3084, Australia. Electronic address: raynerg@unimelb.edu.au.
authors.forename: Genevieve
authors.initials: G
authors.lastname: Rayner
authors.affiliation: The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne Brain Centre, 245 Burgundy Street, Heidelberg, Victoria 3084, Australia; Comprehensive Epilepsy Programme, Austin Health, Melbourne Brain Centre, 245 Burgundy Street, Heidelberg, Victoria 3084, Australia.
authors.forename: Graeme D
authors.initials: GD
authors.lastname: Jackson
authors.affiliation: Melbourne School of Psychological Sciences, The University of Melbourne, Victoria 3010, Australia; The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne Brain Centre, 245 Burgundy Street, Heidelberg, Victoria 3084, Australia; Comprehensive Epilepsy Programme, Austin Health, Melbourne Brain Centre, 245 Burgundy Street, Heidelberg, Victoria 3084, Australia.
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Wilson
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D015897:Comorbidity; D003863:Depression / Q000145:classification / Q000175:diagnosis* / Q000209:etiology*; D004827:Epilepsy / Q000145:classification / Q000150:complications* / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D010865:Pilot Projects; D011340:Problem Solving; D055815:Young Adult
keywords: Brain networks; Cognition; Depression; Diagnosis; Focal epilepsy; Phenotyping