Corpus callosal area differences and gender dimorphism in neuroleptic-naïve, recent-onset schizophrenia and healthy control subjects

Abstract

The study of corpus callosal morphometry is important to unravel the underlying connectivity disturbance in schizophrenia. We studied the corpus callosal area in schizophrenia subjects compared to healthy subjects, while controlling for several confounders that could affect morphometric measures of the corpus callosum (CC). Areas of the whole CC and its sub-regions obtained by two geometric partitioning schemes were studied in 23 right-handed neuroleptic-naïve, recent-onset, schizophrenia patients and compared with 23 right-handed age-, sex- and education-matched healthy subjects. The patients did not differ from controls in whole CC area. On tripartite division of the CC, the area of the anterior sub-region was significantly higher in patients compared to controls. On radial division into 5 sub-regions, the anterior truncus area was significantly higher in patients compared to controls. There was a significant effect of gender (F>M) on the area measures; however there was no significant diagnosis()gender effect. Age, age of onset, duration of illness and psychopathology ratings did not show any significant correlations with whole CC area and area of CC sub-regions. The finding of increased area of the anterior truncus that possibly comprises white fibres connecting the temporal association cortices could be indicative of an "abnormal functional hyperconnection" involving these regions in positive symptom schizophrenia. Additionally, the finding of females having larger areas of the whole CC and of the anterior and middle sub-regions could reflect a "normal hyperconnection" underlying increased ambilaterality in females.

A longitudinal study of the corpus callosum in chronic schizophrenia

“…First, the number of segments entered into statistical analyses of size or anisotropy varied across the studies from 3 to 5 equal divisions, with a single 9-segment study (Rotarska-Jagiela et al, 2008) and two 6-segment studies (Keshavan et al, 2002; Goghari et al, 2005) employing unequal anatomical partitioning schemes (Witelson et al, 1989; Highley et al, 1999). Second, few of the analyses based their segmentation on the medial axis of callosal outline (Downhill et al, 2000; Walterfang et al, 2008b), whereas most others used radial (John et al, 2008) or vertical (Bachmann et al, 2003) partitioning. Utilization of the medial axis, however, provides a better estimate of the shape irregularities of the corpus callosum, especially when more sagittal sections are outlined in addition to the midline, which has thus far been seldom done (Bachmann et al, 2003; Rotarska-Jagiela et al, 2008).…”

“…These segments, starting anteriorly, were anatomically approximated as the rostrum and genu (segment 1), anterior body (segment 2), midbody (segment 3), posterior body (segment 4) and splenium (segment 5). Previous 5-segment parcellations of the corpus callosum in schizophrenia have not shown consensus over the isthmus identification (Venkatasubramanian et al, 2003), variously ascribing it to segment 4 (Bachmann et al, 2003) or 5 (John et al, 2008). We therefore chose to refer to segment 4 as the posterior body and to segment 5 as the splenium.…”

“…Indeed, many morphological and neuroimaging studies have detected abnormalities in callosal shape (DeQuadro et al, 1999; Downhill et al, 2000; Narr et al, 2000; Frumin et al, 2002), size (Arnone et al, 2008; Rotarska-Jagiela et al, 2008), density (Hulshoff-Pol et al, 2004; Seok et al, 2007; Wolf et al, 2008), structure (Flynn et al, 2003; Diwadkar et al, 2004; Kubicki et al, 2005) and function (Innocenti et al, 2003). In contrast to the pioneering postmortem work of Rosenthal and Bigelow (1972), who found dorsoventral dimension of the callosal body increased in schizophrenia patients, most of the following studies using variety of methodologies have found the smaller rather than larger absolute callosal size (see their meta-analyses in Arnone et al, 2008 and Woodruff et al, 1995; and reviews in Innocenti et al, 2003 and Shenton et al, 2001), with few exceptions (Nasrallah et al, 1986; Uematsu and Kaiya, 1988; John et al, 2008). Several of the reports have also found increased curvature of the whole corpus callosum and/or its subdivisions (Downhill et al, 2000; Narr et al, 2000; Frumin et al, 2002), but no differences in full callosal length or its size relative to the whole-brain volume (Woodruff et al, 1995).…”

Functional relevance of interhemispheric fiber tracts in speech processing

“…Thus, an improved interhemispheric connectivity might be disadvantageous for patients with schizophrenia. This aspect is supported by John, Shakeel, and Jain (2008) proposing a so-called "hyperconnectivity" of interhemispheric fibers connecting temporal association cortices as a cause of positive symptoms of schizophrenia.…”

Magnetic resonance imaging study of corpus callosum abnormalities in patients with different subtypes of schizophrenia

“…[13] The inconsistent findings may be a consequence of possible confounding factors, including age, [14] handedness, [15] gender, [16] chronicity of illness [17,18] and differences in CC partitioning schemes employed by the different studies. [19,20] In addition, it was suggested that it may also be owing to the heterogeneity in symptom profiles. [12,18] Schizophrenia is characterised by large heterogeneity, [12,18] and subtypes of schizophrenia may differ in neuroimaging-based measures of brain morphology.…”