title: Frontolimbic brain networks predict depressive symptoms in temporal lobe epilepsy.
abstract: Psychiatric co-morbidities in epilepsy are of great concern. The current study investigated the relative contribution of structural and functional connectivity (FC) between medial temporal (MT) and prefrontal regions in predicting levels of depressive symptoms in patients with temporal lobe epilepsy (TLE). Twenty-one patients with TLE [11 left TLE (LTLE); 10 right TLE (RTLE)] and 20 controls participated. Diffusion tensor imaging was performed to obtain fractional anisotropy (FA) of the uncinate fasciculus (UF), and mean diffusivity (MD) of the amygdala (AM) and hippocampus (HC). Functional MRI was performed to obtain FC strengths between the AM and HC and prefrontal regions of interest including anterior prefrontal (APF), orbitofrontal, and inferior frontal regions. Participants self-reported depression symptoms on the Beck Depression Inventory-II. Greater depressive symptoms were associated with stronger FC of ipsilateral HC-APF, lower FA of the bilateral UF, and higher MD of the ipsilateral HC in LTLE, and with lower FA of the contralateral UF in RTLE. Regression analyses indicated that FC of the ipsilateral HC-APF was the strongest contributor to depression in LTLE, explaining 68.7% of the variance in depression scores. Both functional and microstructural measures of frontolimbic dysfunction were associated with depressive symptoms. These connectivity variables may be moderating which patients present with depression symptoms. In particular, FC MRI may provide a more sensitive measure of depression-related dysfunction, at least in patients with LTLE. Employing sensitive measures of frontolimbic network dysfunction in TLE may help provide new insight into mood disorders in epilepsy that could eventually guide treatment planning.
authors.affiliation: Multimodal Imaging Laboratory, University of California, San Diego, La Jolla, CA, USA; Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA. Electronic address: nkemmotsu@ucsd.edu.
authors.forename: Nobuko
authors.initials: N
authors.lastname: Kemmotsu
authors.affiliation: Multimodal Imaging Laboratory, University of California, San Diego, La Jolla, CA, USA; SDSU/UCSD Joint Doctoral Program in Clinical Psychology, San Diego, San Diego, CA, USA. Electronic address: erkut@ucsd.edu.
authors.forename: N Erkut
authors.initials: NE
authors.lastname: Kucukboyaci
authors.affiliation: Multimodal Imaging Laboratory, University of California, San Diego, La Jolla, CA, USA. Electronic address: kleyden@ucsd.edu.
authors.forename: Kelly M
authors.initials: KM
authors.lastname: Leyden
authors.affiliation: Multimodal Imaging Laboratory, University of California, San Diego, La Jolla, CA, USA. Electronic address: cecheng90@gmail.com.
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Cheng
authors.affiliation: SDSU/UCSD Joint Doctoral Program in Clinical Psychology, San Diego, San Diego, CA, USA. Electronic address: hmgirard@gmail.com.
authors.forename: Holly M
authors.initials: HM
authors.lastname: Girard
authors.affiliation: Department of Neuroscience, University of California, San Diego, La Jolla, CA, USA. Electronic address: viragui@ucsd.edu.
authors.forename: Vicente J
authors.initials: VJ
authors.lastname: Iragui
authors.affiliation: SDSU/UCSD Joint Doctoral Program in Clinical Psychology, San Diego, San Diego, CA, USA; Department of Neuroscience, University of California, San Diego, La Jolla, CA, USA. Electronic address: etecoma@ucsd.edu.
authors.forename: Evelyn S
authors.initials: ES
authors.lastname: Tecoma
authors.affiliation: Multimodal Imaging Laboratory, University of California, San Diego, La Jolla, CA, USA; Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA; SDSU/UCSD Joint Doctoral Program in Clinical Psychology, San Diego, San Diego, CA, USA. Electronic address: camcdonald@ucsd.edu.
authors.forename: Carrie R
authors.initials: CR
authors.lastname: McDonald
mesh_terms: D000328:Adult; D016880:Anisotropy; D001931:Brain Mapping; D003072:Cognition Disorders / Q000209:etiology; D003863:Depression / Q000175:diagnosis* / Q000209:etiology*; D038524:Diffusion Magnetic Resonance Imaging; D004569:Electroencephalography; D004833:Epilepsy, Temporal Lobe / Q000150:complications* / Q000523:psychology; D005260:Female; D005625:Frontal Lobe / Q000473:pathology*; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008032:Limbic System / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000473:pathology; D009483:Neuropsychological Tests; D011237:Predictive Value of Tests; D011569:Psychiatric Status Rating Scales; D014741:Video Recording; D055815:Young Adult
keywords: Comorbidity; DTI; Depression; Functional connectivity; Temporal lobe epilepsy; Uncinate facsiculus