Suppressing traumatic memories can cause amnesia, research suggests

It has long been understood in the world of psychotherapy that traumatic experience frequently leads to suppression of unwanted memories. These unwanted memories become locked away in a kind of time capsule, blocked from consciousness these traumatic experiences continue to exist in a person’s subconscious; simultaneously many emotional states or responses associated with the events also become locked into this time capsule. These unconscious processes that continue to exert themselves on individuals perceptions of life and influence everyday actions. Now there is neurological research to corroborate these findings. Suppressing bad memories from the past can block memory formation in the here and now, research suggests. The following study could help explain why those suffering from post-traumatic stress disorder (PTSD) and other psychological conditions often experience difficulty in remembering recent events.

A recent study (you can read the full article here; Justin C. Hulbert, Richard N. Henson & Michael C. Anderson) “Inducing amnesia through systemic suppression”, explores how forgetting past incidents by suppressing  recollections can create a “virtual lesion” in the brain that casts an “amnesiac shadow” over the formation of new memories. “If you are motivated to try to prevent yourself from reliving a flashback of that initial trauma, anything that you experience around the period of time of suppression tends to get sucked up into this black hole as well,” Dr Justin Hulbert

Decades of research on memory formation show that the hippocampus is essential for constructing new episodic memories. Hippocampal damage irreversibly harms people’s ability to store new memories, causing profound amnesia for life’s events

Reversibly disturbing the hippocampus through optogenetic, electrical and pharmacological interventions temporarily disrupts memory formation. Research indicates that people often downregulate hippocampal activity through cognitive control when they are reminded of an unwelcome event and try to stop retrieval.

Together, these findings imply a striking possibility: if stopping (suppressing) episodic retrieval reduces hippocampal activity, this may broadly disturb all hippocampal functions, including—critically—processes necessary to form and retain new, stable memories.

Retrieval suppression may, in essence, induce a transient ‘virtual lesion’, leaving in its wake, an amnesic shadow for any experiences—whether related or not to the memory being suppressed—that simply have the misfortune of happening near in time to efforts to forget.

Professor Chris Brewin, an expert in PTSD from University College, London, who was not involved in the study.

“I think it makes perfect sense because we know that people with a wide range of psychological problems have difficulties with their everyday memories for ordinary events,” “Potentially this could account for the memory deficits we find in depression and other disorders too.”  (Guardian 15 March 2016)