Women with a history of childhood maltreatment exhibit more activation in association areas following non-traumatic olfactory stimuli: a fMRI study

Abstract

Background: The aim of this study was investigating how women with a history of childhood maltreatment (CM) process non-threatening and non-trauma related olfactory stimuli. The focus on olfactory perception is based on the overlap of brain areas often proposed to be affected in CM patients and the projection areas of the olfactory system, including the amygdala, orbitofrontal cortex, insula and hippocampus.

Methods: Twelve women with CM and 10 controls participated in the study. All participants were, or have been, patients in a psychosomatic clinic. Participants underwent a fMRI investigation during olfactory stimulation with a neutral (coffee) and a pleasant (peach) odor. Furthermore, odor threshold and odor identification (Sniffin' Sticks) were tested.

Principal findings: Both groups showed normal activation in the olfactory projection areas. However, in the CM-group we found additionally enhanced activation in multiple, mainly neocortical, areas that are part of those involved in associative networks. These include the precentral frontal lobe, inferior and middle frontal structures, posterior parietal lobe, occipital lobe, and the posterior cingulate cortex.

Conclusions: The results indicate that in this group of patients, CM was associated with an altered processing of olfactory stimuli, but not development of a functional olfactory deficit. This complements other studies on CM insofar as we found the observed pattern of enhanced activation in associative and emotional regions even following non-traumatic olfactory cues.

Figure 1. Hedonic and intensity ratings (means, standard deviations [SD]) for peach-odor and the coffee-like odor in CM- and control group.

Higher ratings mean greater perceived pleasantness and/or intensity. For convenience, standard deviations are presented one-sided.

Figure 2. Activated clusters (k≥6; p≤0.001) for both odors in the CM group (orange) and in the controls (blue) (contrasts: ON vs. OFF separately for the two groups).

For visualization, we used a normalized template, provided by SPM 5 –Software (single_subj_T1.nii).

Figure 3. Activated clusters for contrast: CM group vs. control group in the x = −6 slice (k≥6; p≤0.001) for both odors.

The CM group (orange) exhibits activation in the posterior cingulate cortex (PCC) while control subjects (blue) show activation in the anterior cingulate cortex (ACC). For visualization, we used a normalized template, provided by SPM 5 –Software (single_subj_T1.nii).