Which is a symptom of intrusive trauma that persists beyond a month after the event?

A symptom of intrusive trauma that persists beyond a month after the event is physical reactivity. This can manifest as heightened arousal, such as an increased heart rate, sweating, or a startle response when reminded of the traumatic experience. Physical reactivity is a hallmark symptom often associated with post-traumatic stress disorder (PTSD) and reflects the body's physiological response to trauma.

On the other hand, constricted emotions generally refer to a dampening or suppression of emotional expression, which may not specifically indicate reactivity. Avoidance of crowds can be a coping mechanism for those who have experienced trauma, where individuals steer clear of reminders of the traumatic event. Increased social interactions, however, is not typically a symptom associated with trauma; rather, trauma often leads individuals to withdraw or isolate themselves. Thus, physical reactivity stands out as the most pertinent symptom in the context of intrusive trauma that lingers past a month.