Joseph Riordan – Clinical Psychologist, Qld

Topic: Monozgotic Twins – The contagious nature of trauma in attachment dyads when one twin experiences trauma. (Case Study)

Presentation

Monozygotic twins offer a unique research opportunity to examine the contagious nature of trauma in attachment dyads when one twin experiences trauma, but the other does not. Monozygotic twins share a unique form of sibling attachment, described here as monozygotic attachment, characterised by elevated somatic congruence resulting in suboptimal sibling attachment when trauma enters the dyad.

A quantitative experimental approach was used to examine the nature of trauma in a 13-year-old male twin pair and the significance of trauma in their sibling attachment dyad.

Smartphone devices were used to record seven autonomic variables pre- and post-treatment for both twins: heart rate variability (HRV), three HRV index variables, heart rate, sleep duration, and sleep disturbances. Mean and small sample t-tests were applied to determine statistical significance.

This and other research conducted by Joseph over a decade confirm attachment perturbations in trauma are complicit in widespread community psychopathology Including loneliness, social isolation, and loss of social cohesion.

A Webinar not to be missed!

Saturday 16 May 2026 from 10 am - 12 noon AEST 

Joseph Riordan has been a psychologist in private practice for 38 years. His early introduction to trauma was with WWII veterans. Throughout his career Joseph has treated war, civic and episodic trauma and now focuses his academic interest on the neuroscience of attachment and Dyadic Trauma.

Joseph’s practice of psychology has been characterised by his search for better outcomes with treatments “that work”. Combining evidence-based treatments with emerging theories of traumatology has been an enduring interest.

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