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ADRA2B Deletion Variant Selectively Predicts Stress-induced Enhancement of Long-term Memory in Females

Phillip Zoladz, Andrea E. Kalchik, Chelsea E. Cadle, Mackenzie M. Hoffman, Rachael Aufdenkampe, Sarah M. Lyle, Callie M. Brown, Amanda R. Scharf, Alison M. Dailey, Nicholas Wolters, Jeffrey N. Talbot, Boyd R. Rorabaugh
Ohio Northern University

Clarifying the mechanisms that underlie stress-induced alterations of learning and memory may lend important insight into susceptibility factors governing the development of stress-related psychological disorders, such as post-traumatic stress disorder (PTSD).  Previous work has shown that carriers of the ADRA2B deletion variant exhibit enhanced emotional memory, greater amygdala responses to emotional stimuli, and greater intrusiveness of traumatic memories.  We speculated that carriers of this deletion variant might also be more vulnerable to stress-induced enhancements of long-term memory, which would implicate the variant as a possible susceptibility factor for traumatic memory formation.  In the present study, participants submerged their hand in ice cold (stress) or warm (no stress) water for 3 min.  Immediately thereafter, they studied a list of 42 words varying in emotional valence and arousal and then completed an immediate recall test.  Twenty-four hours later, participants’ memory for the list was examined via free recall and recognition assessments.  Stressed participants exhibiting greater heart rate responses to the stressor had enhanced recall on the 24-hr assessment.  More importantly, stressed female ADRA2B deletion carriers, particularly those exhibiting greater heart rate responses to the stressor, demonstrated greater recognition memory than all other groups.  These findings support our hypothesis that the ADRA2B deletion variant is associated with increased susceptibility to stress-induced enhancements of learning.  Furthermore, they extend this speculation by revealing that females are selectively influenced by the genetic variant, which could lend insight into sex-dependent susceptibility to traumatic memory formation and PTSD.