Verbal fluency deficits and altered lateralization of language brain areas in individuals genetically predisposed to schizophrenia

Bhojraj, Tejas S; Francis, Alan N; Rajarethinam, Rajaprabhakaran; Eack, Shaun; Kulkarni, Shreedhar; Prasad, Konasale M; Montrose, Debra M; Dworakowski, Diana; Diwadkar, Vaibhav; Keshavan, Matcheri S

doi:10.1016/j.schres.2009.09.033

« Previous Next »Schizophrenia Research
Volume 115, Issue 2 , Pages 202-208, December 2009

Verbal fluency deficits and altered lateralization of language brain areas in individuals genetically predisposed to schizophrenia

Tejas S Bhojraj
- Department of Psychiatry, Beth Israel Deaconess Medical Center and Massachusetts Mental Health Center; Harvard Medical School, Boston, MA, USA
Alan N Francis
- Department of Psychiatry, Beth Israel Deaconess Medical Center and Massachusetts Mental Health Center; Harvard Medical School, Boston, MA, USA
Rajaprabhakaran Rajarethinam
- Wayne State University, Detroit, Michigan, USA
Shaun Eack
- Western Psychiatric Institute and Clinic, Pittsburgh, Pennsylvania, USA
Shreedhar Kulkarni
- Department of Psychiatry, Beth Israel Deaconess Medical Center and Massachusetts Mental Health Center; Harvard Medical School, Boston, MA, USA
Konasale M Prasad
- Western Psychiatric Institute and Clinic, Pittsburgh, Pennsylvania, USA
Debra M Montrose
- Western Psychiatric Institute and Clinic, Pittsburgh, Pennsylvania, USA
Diana Dworakowski
- Wayne State University, Detroit, Michigan, USA
Vaibhav Diwadkar
- Wayne State University, Detroit, Michigan, USA
Matcheri S Keshavan
- Department of Psychiatry, Beth Israel Deaconess Medical Center and Massachusetts Mental Health Center; Harvard Medical School, Boston, MA, USA
- Wayne State University, Detroit, Michigan, USA
- Western Psychiatric Institute and Clinic, Pittsburgh, Pennsylvania, USA
- Corresponding author. Beth Israel Deaconess Medical Center, Department of Psychiatry, Massachusetts Mental Health Center, 401 Park Drive, Room 2P12, The Landmark Center, Boston, MA 02215, USA.

Received 28 July 2009; received in revised form 18 September 2009; accepted 22 September 2009. published online 19 October 2009.

Abstract

Alterations of verbal fluency may correlate with deficits of gray matter volume and hemispheric lateralization of language brain regions like the pars triangularis (PT) in schizophrenia. Examining non-psychotic individuals at high genetic risk (HR) for schizophrenia may clarify if these deficits represent heritable trait markers or state dependent phenomena. We assessed adolescent and young adult HR subjects (N=60) and healthy controls (HC; N=42) using verbal fluency tests and Freesurfer to process T1-MRI scans. We hypothesized volumetric and lateralization alterations of the PT and their correlation with verbal fluency deficits. HR subjects had letter verbal fluency deficits (controlling for IQ), left PT deficits (p=.00), (controlling ICV) and reversal of the L>R PT asymmetry noted in HC. Right Heschl's (p=.00), left supramarginal (p=.00) and right angular gyrii (p=.02) were also reduced in HR subjects. The L>R asymmetry of the Heschl's gyrus seen in HC was exaggerated and asymmetries of L>R of supramarginal and R>L of angular gyri, seen in HC were attenuated in HR subjects. L>R asymmetry of the PT predicted better verbal fluency across the pooled HR and HC groups. Young relatives of schizophrenia patients have verbal fluency deficits, gray matter volume deficits and reversed asymmetry of the pars triangularis. A reversed structural asymmetry of the PT in HR subjects may impair expressive language abilities leading to verbal fluency deficits. Volumetric deficits and altered asymmetry in inferior parietal and Heschl's gyrii may accompany genetic liability to schizophrenia.