Antibiotic Doxycycline May Block PTSD Symptoms

October 10, 2017 · Posted in Potential Treatments · Comment 

doxycycline capsulesA 2017 proof-of-concept study suggests that the antibiotic doxycycline can block the formation of negative thoughts and fear memories, perhaps offering a new way to treat or prevent post-traumatic stress disorder (PTSD).

In the study by Dominik R. Bach in the journal Molecular Psychiatry, healthy adults who received doxycycline had a lower fear response to fearful stimuli compared to healthy adults who received a placebo. The 76 participants received either doxycycline or placebo and then were taught to associate a color with an electric shock. Later, they were exposed to the color accompanied by a loud sound (but no shock), and their startle response was measured by tracking eye blinks, an instinctive response to sudden threats. Bach and colleagues found that the fear response was 60% lower in those participants who received doxycycline, suggesting that the antibiotic disrupted the fear memory linking the color to a threat.

The theory is based on evidence that doxycycline can inhibit metalloproteinase enzymes, which are involved in memory formation.

While in the study doxycycline was delivered before the fearful event occurred, there is hope that the antibiotic could also do some good after the fact. There is growing evidence that actively recalling a traumatic event can open a ‘memory reconsolidation window’ during which emotions associated with that event are open to change. Bach and colleagues hope to follow up with studies involving this reconsolidation window.

Another line of research is exploring how pain medications may reduce the emotional power of traumatic memories, because intense pain strengthens memory consolidation.

Revising Traumatic Memories in the Reconsolidation Window

October 6, 2017 · Posted in Potential Treatments · Comment 

elderly womanWe have previously described in the BNN how therapies can take advantage of the memory reconsolidation window to reduce the power of traumatic memories. Five minutes to one hour following active emotional recall of a traumatic event, a ‘window’ opens during which therapies can revise or extinguish the traumatic memory. A 2017 article by our Editor-in-Chief Robert M. Post and Robert Kegan in the journal Psychiatric Research describes how the reconsolidation window could theoretically be used to prevent recurring depressive episodes.

The theory is based on the idea that depressive episodes initially stem from stressors, but eventually become ingrained in the brain’s habit memory system. Cognitive behavioral therapy during the memory reconsolidation window might be a good way to disrupt these habit memories.

The memory reconsolidation window has already been used successfully to reduce traumatic memories and even to reduce heroin and cocaine cravings in addiction. The idea in changing traumatic memories, in the words of researcher Göran Högberg in a 2011 article in the journal Psychology Research in Behavior Management, is to “change a reliving intruding memory into a more distant episodic memory.” Post and Kegan suggest that work in depression would have a similar goal, to rework the triggering experience and render the depressive experience “less harsh, severe, [and] self-defeating (guilt-inducing).”
In exploring this new therapeutic approach, Post and Kegan suggest that it might be best to begin with patients whose depressive episodes are triggered by stressors.

The patient would be encouraged to recall the memory of the particular stressor and any emotions related to it. Then they would be prompted to reframe the memory, either by recognizing adaptive aspects of their response, focusing on their youth at the time of the stressor in the case of childhood memories, addressing any guilt the patient may feel, or other techniques used in trauma therapy. Evoking positive feelings during this period via relaxation exercises would be another useful practice.

In addition to targeting stressors that precede depression, the stress of the depressive experience itself could be a target of reframing during the reconsolidation window.
Questions remain, such as whether to target early or more recent memories, and whether this technique would be as useful in reducing manic episodes. Patient characteristics might also affect the success of this type of therapeutic intervention.

Post and Kegan also address how the therapy might be used in different stages of illness, and how it might be combined with other therapies, such as medications or procedures such as repeated transcranial magnetic stimulation (rTMS).

Using the Memory Reconsolidation Window to Extinguish Drug Craving and Use

November 28, 2012 · Posted in Potential Treatments · Comment 

In last week’s article we discussed how fearful memories can be changed during the window in which they are reconsolidated (5 minutes to 1 hour after active recall of the long-term memory). Now the memory reconsolidation window has been used in animals and people to extinguish an addiction to cocaine or heroin. The results in humans were reported by Xue et al. in the journal Science in April 2012.

cocaine

In a typical recovery scenario, a cocaine addict is repeatedly presented cocaine cues (such as paraphernalia) without the delivery of cocaine, and craving for cocaine becomes extinguished. While the patient stops craving the drug, some biological signs of the addiction remain, such as autonomic hyper-reactivity (e.g. changes in skin conductance, pulse, or blood pressure) in response to the cocaine cues. When the sober cocaine addict leaves the recovery program, he may believe he is no longer subject to cocaine craving even upon the sight of cocaine-related cues, but this craving can return spontaneously or be reactivated by cocaine-related environments or friends who were also users, and he typically relapses.

In order to make the extinction learning more powerful, it must be experienced during the reconsolidation window. In the animal experiments by Xue et al., rodents were trained to press a lever to receive an injection of cocaine or heroin. In the extinction process, the animals were returned for 15 minutes to the same environment where they had learned to press the lever and receive the drug. This was meant to activate memories associated with the drug. Then, after a 10-minute waiting period, a 180-minute extinction training was given. The process was repeated daily for 14 days and resulted in almost complete absence of relapse to drug use with passage of time (spontaneous recovery), exposure to the drug (reinstatement), or exposure to the drug-associated environment (renewal). Moreover, the expected changes in heart rate and blood pressure upon re-exposure to the drug cues were also fully extinguished. Extinction training that began one hour after activation of the memory was also successful.

When the same extinction training was given 6 hours after placing the animal in the drug administration environment, the animal remained prone to drug re-instatement and relapse in the same or different environments or spontaneously. It can be presumed that this occurred because the extinction training took place after the reconsolidation window had closed.

These well-controlled data with both cocaine and heroin self-administration in animals were then taken to the clinic to test their validity in humans.

The same procedure worked in humans addicted to heroin.  Two consecutive days of sixty-minute extinction learning within the reconsolidation window, i.e. starting 10 minutes after a 5-minute retrieval of drug-associated memories by watching a video resulted in amelioration of drug craving for at least 184 days, and amazingly, as in the animals, also resulted in the loss of the unconscious biological reactivity in heart rate and to a lesser extent, blood pressure.  Patients did not relapse during 6 months of followup.  The same extinction process was unsuccessful when it occurred outside of the reconsolidation window, i.e. 6 hours after retrieving the drug-related memories.

Editor’s Note: These results could be of considerable potential therapeutic value in a variety of psychiatric illnesses. This process is conceptual breakthrough that has great promise for clinical use.  Psychiatrists, psychologists, and patients should become familiar with these data and the principles of exploiting the reconsolidation window for potentially transformational results.

How quickly these principles can be incorporated into mainstream psychotherapeutic encounters remains to be seen.  However, clinicians should begin to familiarize themselves with these data and concepts so that they can soon be put to use for more effective clinical treatment of psychiatric conditions involving pathological learning, conditioning, and habits.

Opening The Reconsolidation Window to Extinguish Fear Memories: A New Conceptual Approach to Psychotherapeutics

November 20, 2012 · Posted in Potential Treatments · Comment 

fearMemory processes occur in several phases. Short-term memory is converted to long-term memory by a process of consolidation that requires the synthesis of new proteins. Transcription factors in the nuclei of hundreds of millions of nerve cells are activated so that specific synapses can be modified for the long term. If protein synthesis is inhibited during a period within a few hours after new learning has occurred, what was learned never gets consolidated and is essentially forgotten. It is thought that this phase of consolidation happens when a memory trace moves from short-term storage in the hippocampus to long-term storage in the cerebral cortex.

Recently a later phase of memory storage called reconsolidation has been identified. When an old memory is recalled, the reconsolidation window opens, and the memory trace becomes temporarily amenable to change. The reconsolidation window (the period during which the trace can be revised) is thought to begin five minutes after a memory is recalled and last for an hour or possibly two. New learning that takes place during the reconsolidation window can be more profound than learning that occurs without recall of the related memory or after the reconsolidation window has closed.

Consider the example of a fearful memory created when a person is attacked in a dark alley. If the person repeatedly visits the same alley without being attacked, they can eventually become less afraid of dark places. Repeated viewing of pictures of dark places can also extinguish the fear. These are typical ways in which a fear memory is extinguished. However, the original fear is subject to spontaneous recovery (the fear of dark places returns without provocation) or to reactivation (if another dangerous situation is encountered, the person may regain their fear of dark alleys).

The new findings suggest that if the extinction process (the repeated exposures to the pictures of the dark alley) takes place during the reconsolidation window after the fear memory of being attacked is recalled, the old fear can be permanently reversed (wiped clean, or re-edited such that it appears forgotten) so that it is no longer subject to spontaneous recovery or reactivation.

Editor’s Note: To accomplish extinction training within the reconsolidation window, first a person must actively recall the old memory, opening the reconsolidation window. Then, after a 5-minute delay, extinction training (e.g. new learning that the old feared place is now safe) should take place within the next hour. This process has been demonstrated in animal studies and is thought to be clinically relevant for humans in the case of phobic anxiety and post-traumatic stress disorder (PTSD). The psychotherapeutic implications of using the reconsolidation window to better ameliorate PTSD fears, avoidance, and flashbacks are enormous.

Observing the Amygdala’s Role in the Extinction of Fear Memory Traces

The amygdala is a crucial part of the learned or conditioned fear pathway. It is activated during fear conditioning and during the recall of cues associated with the fear experience. If the amygdala is removed, conditioning fear does not occur.

A new study published in Science this year by Agren et al. indicates that in humans, the amygdala-based response to conditioned fear can be completely abolished using extinction training within the memory reconsolidation window. Training that took place 10 minutes after the fear memory was activated was successful, while training that took place 6 hours later was not. Read more