Olfactory sulcal depth and olfactory bulb volume in patients with schizophrenia: an MRI study

Abstract

The current report used structural magnetic resonance imaging (MRI) to objectively measure olfactory bulb volume and olfactory sulcal depth in patients diagnosed with chronic schizophrenia and healthy controls. Additional measures were obtained to assess olfactory function. The olfactory bulb and sulcus were manually traced on structural 3T MRIs for 25 right-handed male patients diagnosed with chronic schizophrenia and 25 matched male healthy controls. A sub-set of subjects received the University of Pennsylvania Smell Identification Test (UPSIT). Olfactory bulb volume was significantly decreased in patients with schizophrenia compared to healthy controls, as was their performance on the UPSIT. Additionally, a positive correlation was seen in patients between right bulb volume and UPSIT scores. Overall, our findings support earlier research studies showing morphometric and functional changes in the olfactory system in patients with schizophrenia.

Brain Changes in Kallmann Syndrome

“…[7][8][9][10][11][12] Olfactory sulcus abnormalities have been associated with embryogenic olfactory bulb-inducted processes. 10,11,30,31 In patients with KS, the aplasia/hypoplasia of the olfactory bulbs is associated with an ipsilaterally decreased depth of the olfactory sulcus, which might turn medially, opening anteriorly into the interhemi- spheric fissure. 7 Indeed, as shown in Fig 2, the olfactory sulcus presented with decreased sulcation and curvature, while the medial orbital-frontal sulcus showed a "compensatory-like" increased sulcation and curvature.…”

The influences of age on olfaction: a review

“…Thus, olfactory bulb volume is reduced in cigarette smokers (Schriever et al, 2013) and in those with a number of neurological diseases or other disorders (Yousem et al, 1995b). These include acute depression (Negoias et al, 2010), Alzheimer's disease (Thomann et al, 2009), childhood abuse (Croy et al, 2013), chronic sinusitis (Rombaux et al, 2008), congential anosmia with and without Kallmann syndrome (Yousem et al, 1993, 1996; Abolmaali et al, 2002; Koenigkam-Santos et al, 2011; Levy et al, 2013), epilepsy (Hummel et al, 2012), head trauma (Yousem et al, 1995a; Doty et al, 1997; Landis et al, 2005; Jiang et al, 2009), multiple sclerosis (Goektas et al, 2011; Schmidt et al, 2011), Parkinson's disease (Wang et al, 2011b; Brodoehl et al, 2012), polyposis (Herzallah et al, 2013), schizophrenia (Turetsky et al, 2003; Nguyen et al, 2011), and prior upper respiratory infections associated with chronic smell loss (Rombaux et al, 2009). Such studies strongly suggest that olfactory bulb volume is a marker for olfactory function in general (Yousem et al, 1998; Turetsky et al, 2003; Buschhuter et al, 2008; Haehner et al, 2008; Hummel et al, 2011; Rombaux et al, 2012).…”

Molecular evidence for decreased synaptic efficacy in the postmortem olfactory bulb of individuals with schizophrenia

“…Individuals with schizophrenia and those at high risk exhibit deficits in multiple domains of olfactory function including deficits in odor identification (Moberg et al, 1997), odor detection threshold sensitivity (Rupp et al, 2005), odor discrimination (Rupp et al, 2005) and odor memory and odor hedonic judgments (Moberg et al, 2014; Moberg and Turetsky, 2003; Nguyen et al, 2011; Turetsky et al, 2009; Turetsky et al, 2003b). Interestingly, a lesser degree of olfactory dysfunction also may be found among patients’ family members (Moberg et al, 2014) but see (Compton and Chien, 2008; Kamath et al, 2013), suggesting a heritability of this phenotype.…”

“…Structural and functional alterations in the olfactory circuitry have been reported in schizophrenia (Arnold et al, 2001; Kamath et al, 2011; Nguyen et al, 2011; Rioux et al, 2004). Olfactory event related potentials that are measured in response to odorant stimulation were found to be decreased in patients with schizophrenia compared to controls (Turetsky, 2003a) which indicates an overall decrease in odorant induced neural transmission.…”

“…Olfactory event related potentials that are measured in response to odorant stimulation were found to be decreased in patients with schizophrenia compared to controls (Turetsky, 2003a) which indicates an overall decrease in odorant induced neural transmission. Such changes could be in part due to structural changes in key regions of the circuit, as evidenced by decreased size of the OB (Turetsky et al, 2003a; Turetsky et al, 2000) and olfactory sulci (Nguyen et al, 2011; Takahashi et al, 2013a; Takahashi et al, 2013b; Takahashi et al, 2014) in schizophrenia patients and individuals at high risk. In addition, histologic examination of the postmortem OE showed increased ratios of immature vs. mature (GAP-43 immunoreactive vs. OMP immunoreactive) neurons (Arnold et al, 2001), suggesting that altered neuronal maturation may impact olfactory neuron function in schizophrenia patients.…”