Background:


Secure attachment is important in maintaining an individual's
health and well-being. Attachment disturbances increase the risk for
developing psychiatric disorders such as affective disorders. Yet, the
neurobiological correlates of human attachment are poorly understood at
the neurotransmitter level. We investigated whether adult attachment
style is linked to functioning of the opioid and serotonergic systems in
the human brain.

Methods:


We used positron emission tomography with radioligands [¹¹C]carfentanil and [¹¹C]MADAM
to quantify mu opioid receptor (n = 39) and serotonin transporter (n =
37) availability in volunteers with no current psychiatric disorders.
Attachment style was determined according to the Dynamic-Maturational
Model of Attachment and Adaptation with the structured Adult Attachment
Interview.

Results:


Secure attachment was associated with higher mu opioid receptor
availability in the hippocampus, amygdala, thalamus, and prefrontal
cortex when compared with insecure (i.e., avoidant or ambivalent groups
combined) attachment. In contrast, attachment style was not associated
with serotonin transporter availability.

Conclusions:


Our results provide preliminary in vivo evidence that the opioid
system may be involved in the neurocircuits associated with individual
differences in adult attachment behavior. The results suggest that
variation in mu opioid receptor availability may be linked with the
individuals' social relationships and psychosocial well-being and thus
contributes to risk for psychiatric morbidity.

Keywords:


Attachment; Neurotransmission; Opioid; Positron emission tomography; Serotonin.