Tonic immobility differentiates stress responses in PTSD.

Area of Science:

• Psychology
• Neuroscience
• Human Physiology

Background:

• Tonic immobility (TI) is a physical immobility state linked to extreme stress and posttraumatic stress disorder (PTSD).
• The objective stress response associated with TI, measured by body sway, remains largely unexplored.
• This study investigates the relationship between TI and objective stress responses, comparing PTSD patients and healthy controls.

Purpose of the Study:

• To explore the association between tonic immobility (TI) and objective stress responses using stabilometric measures.
• To investigate differences in body sway responses during stress induction between individuals with PTSD and healthy controls.
• To determine if TI is associated with a distinct stress response pattern, characterized by immobility.

Main Methods:

• Participants included 12 PTSD patients and 12 healthy controls.
• Stress was induced via eye closure and a mental arithmetic task.
• Body sway and heart rate were measured across four conditions: eyes open/closed and with/without mental arithmetic.

Main Results:

• PTSD patients exhibited increased body sway with eyes closed compared to controls.
• The arithmetic task eliminated the increased body sway effect in PTSD patients.
• Self-reported TI correlated with reduced body sway increases in PTSD patients and greater sway decreases in controls during eye closure.

Conclusions:

• Eye closure differentially affects body sway in PTSD patients versus controls.
• High self-reported TI may indicate a proneness for immobility as a stress response.
• Individual differences in stress response patterns, including TI, may be relevant for optimizing PTSD treatment.