The Interplay of Oxytocin and Attachment in Schizophrenic Patients: An fMRI Study

Abstract

Background: Attachment theory offers an important framework for understanding interpersonal interaction experiences. In the present study, we examined the neural correlates of attachment patterns and oxytocin in schizophrenic patients (SZP) compared to healthy controls (HC) using fMRI. We assumed that male SZP shows a higher proportion of insecure attachment and an altered level of oxytocin compared to HC. On a neural level, we hypothesized that SZP shows increased neural activation in memory and self-related brain regions during the activation of the attachment system compared to HC.

Methods: We used an event-related design for the fMRI study based on stimuli that were derived from the Adult Attachment Projective Picture System to examine attachment representations and their neural and hormonal correlates in 20 male schizophrenic patients compared to 20 male healthy controls.

Results: A higher proportion of insecure attachment in schizophrenic patients compared to HC could be confirmed. In line with our hypothesis, Oxytocin (OXT) levels in SZP were significantly lower than in HC. We found increasing brain activations in SZP when confronted with personal relevant sentences before attachment relevant pictures in the precuneus, TPJ, insula, and frontal areas compared to HC. Moreover, we found positive correlations between OXT and bilateral dlPFC, precuneus, and left ACC in SZP only.

Conclusion: Despite the small sample sizes, the patients' response might be considered as a mode of dysregulation when confronted with this kind of personalized attachment-related material. In the patient group, we found positive correlations between OXT and three brain areas (bilateral dlPFC, precuneus, left ACC) and may conclude that OXT might modulate within this neural network in SZP.

Keywords: attachment; fMRI; interpersonal functioning; neuroimaging; oxytocin; schizophrenia; social cognition; social emotion; theory of mind.

Figure 1

Stimuli were presented within two blocks of six trials each. Each block contained three different sets of personally relevant sentences and neutral sentences for each picture stimulus. Trials alternated between personally relevant and neutral in groups of seven AAP picture stimuli. Pictures were presented in the same order as in the interview to activate the attachment system. In total, there were 84 trials resulting in a scanning time of about 28 min. One measurement consists of 2 blocks of 6 single trials each with 440 scans for each functional run. After each trial started the sentence and the picture were presented for a total of 9.4 s. This was followed by 9.9 s of fixation (inter-stimulus interval).

Figure 2

Proportional distribution of attachment classifications of patients and healthy controls by χ²-testing.

Figure 3

T-contrast personally relevant > neutral, activations SZP > HC: bilateral precuneus and temporoparietal junction; cingulate gyrus and insula (Peak-level: p < 0.05, FDR-corrected, cluster level: p < 0.05, FDR-corrected; L = left, R = right; statistical pictures showing the activation on a color scale from dark red to light yellow = statistical with yellow symbolizing stronger activation and red symbolizing weaker activation).

Figure 4

Positive correlation between oxytocin scores and ROI activation of (r_lP = 0.501, p < 0.025; r_rP = 0.520, p < 0.019) and bilateral TPJ (r_lTPJ = 0.462, p < 0.040; r_rTPJ = 0.543, p < 0.013; L = left, R = right) in patients, statistical pictures showing the activation on a color scale from dark red to light yellow = statistical with yellow symbolizing stronger activation and red symbolizing weaker activation.

Figure 5

T-contrast personally relevant > neutral, activations disorganized/unresolved patients > organized/resolved patients (Peak-level: p < 0.001, uncorrected, additional threshold: 50 voxels, R = right, L = left; statistical pictures showing the activation on a color scale from dark red to light yellow = statistical with yellow symbolizing stronger activation and red symbolizing weaker activation).

Figure 6

ToM-Network of mentalization (adapted from Abu-Akel and Shamay-Tsoory [113]).