Blocking a newly identified memory pathway could prevent the disorder
About 8 million Americans suffer from nightmares and flashbacks to a traumatic event. This condition, known as post-traumatic stress disorder (PTSD), is particularly common among soldiers who have been in combat, though it can also be triggered by physical attack or natural disaster.
Studies have shown that trauma victims are more likely to develop PTSD if they have previously experienced chronic stress, and a new study from MIT may explain why. The researchers found that animals who underwent chronic stress prior to a traumatic experience engaged a distinctive brain pathway that encodes traumatic memories more strongly than in unstressed animals.
Blocking this type of memory formation may offer a new way to prevent PTSD, says Ki Goosens, the senior author of the study, which appears in the journal Biological Psychiatry.
“The idea is not to make people amnesic but to reduce the impact of the trauma in the brain by making the traumatic memory more like a ‘normal,’ unintrusive memory,” says Goosens, an assistant professor of neuroscience and investigator in MIT’s McGovern Institute for Brain Research.
The paper’s lead author is former MIT postdoc Michael Baratta.
Goosens’ lab has sought for several years to find out why chronic stress is so strongly linked with PTSD. “It’s a very potent risk factor, so it must have a profound change on the underlying biology of the brain,” she says.
To investigate this, the researchers focused on the amygdala, an almond-sized brain structure whose functions include encoding fearful memories. They found that in animals that developed PTSD symptoms following chronic stress and a traumatic event, serotonin promotes the process of memory consolidation. When the researchers blocked amygdala cells’ interactions with serotonin after trauma, the stressed animals did not develop PTSD symptoms. Blocking serotonin in unstressed animals after trauma had no effect.
“That was really surprising to us,” Baratta says. “It seems like stress is enabling a serotonergic memory consolidation process that is not present in an unstressed animal.”
Memory consolidation is the process by which short-term memories are converted into long-term memories and stored in the brain. Some memories are consolidated more strongly than others. For example, “flashbulb” memories, formed in response to a highly emotional experience, are usually much more vivid and easier to recall than typical memories.
Goosens and colleagues further discovered that chronic stress causes cells in the amygdala to express many more 5-HT2C receptors, which bind to serotonin. Then, when a traumatic experience occurs, this heightened sensitivity to serotonin causes the memory to be encoded more strongly, which Goosens believes contributes to the strong flashbacks that often occur in patients with PTSD.
“It’s strengthening the consolidation process so the memory that’s generated from a traumatic or fearful event is stronger than it would be if you don’t have this serotonergic consolidation engaged,” Baratta says.
“This study is a very nice dissection of the mechanism by which chronic stress seems to activate new pathways not seen in unstressed animals,” says Mireya Nadal-Vicens, medical director of the Center for Anxiety and Traumatic Stress Disorders at Massachusetts General Hospital, who was not part of the research team.
This memory consolidation process can take hours to days to complete, but once a memory is consolidated, it is very difficult to erase. However, the findings suggest that it may be possible to either prevent traumatic memories from forming so strongly in the first place, or to weaken them after consolidation, using drugs that interfere with serotonin.
“The consolidation process gives us a window in which we can possibly intervene and prevent the development of PTSD. If you give a drug or intervention that can block fear memory consolidation, that’s a great way to think about treating PTSD,” Goosens says. “Such an intervention won’t cause people to forget the experience of the trauma, but they might not have the intrusive memory that is ultimately going to cause them to have nightmares or be afraid of things that are similar to the traumatic experience.”
The Food and Drug Administration has already approved a drug called agomelatine that blocks this type of serotonin receptor and is used as an antidepressant.
Such a drug might also be useful to treat patients who already suffer from PTSD. These patients’ traumatic memories are already consolidated, but some research has shown that when memories are recalled, there is a window of time during which they can be altered and reconsolidated. It may be possible to weaken these memories by using serotonin-blocking drugs to interfere with the reconsolidation process, says Goosens, who plans to begin testing that possibility in animals.
The findings also suggest that the antidepressant Prozac and other selective serotonin reuptake inhibitors (SSRIs), which are commonly given to PTSD patients, likely do not help and may actually worsen their symptoms. Prozac enhances the effects of serotonin by prolonging its exposure to brain cells. While this often helps those suffering from depression, “There’s no biological evidence to support the use of SSRIs for PTSD,” Goosens says.
Read more: Possible new weapon against PTSD
The Latest on: PTSD Cure
via Google News
The Latest on: PTSD Cure
- 'I think they’re waiting for me to die': It took nearly a decade for a veteran to receive VA exam for post-traumatic stresson November 30, 2021 at 6:57 am
Maurice Thomas served in the U.S. Marine Corps, watching people die around him. He filed a compensation claim for PTSD in 2010, and he's still going through the appeals process.
- Some veteran 'suicides' could be deaths from drugs prescribed for PTSD, psychiatrist tells royal commissionon November 30, 2021 at 4:43 am
Consultant psychiatrist Dr Andrew Khoo says more than 70 different drugs are being prescribed to veterans for PTSD. He tells the Royal Commission into Defence and Veteran Suicide they could be causing ...
- Bright Minds Biosciences Provides Scientific Update on its Novel 5-HT2A Psychedelic Program for the Treatment of Mental Diseaseson November 30, 2021 at 4:30 am
Hundreds of de novo patentable psychedelic-based compounds created through discovery program — — Company plans to announce lead molecule in first quarter of 2022 — VANCOUVER, British Columbia, Nov. 30 ...
- Closure of local PTSD clinic is putting lives at risk, says war veteranon November 29, 2021 at 8:00 pm
THE closure of a post-traumatic stress disorder clinic in Townsville puts lives at risk, an Afghanistan war veteran says.
- What is PTSD? Experts on the symptoms, treatment and causes as Japan’s ex-princess Mako shows it can strike anyoneon November 29, 2021 at 8:15 am
Following intense media focus on the former Japanese princess’s mental health, experts describe the causes, symptoms and treatment of PTSD, and how to help someone who might have it.
- Psychedelics Show Promise in Treating Mental Illness: Depression, Anxiety, Addiction, and PTSDon November 29, 2021 at 1:33 am
One in five U.S. adults will experience a mental illness in their lifetime, according to the National Alliance of Mental Health. But standard treatments can be slow to work and cause side effects. To ...
- Great Falls doctor is injecting new hope for PTSD patientson November 25, 2021 at 8:38 am
About 15 million adults have PTSD during a given year. About 8% of women develop PTSD sometime in their lives, compared with about 4% of men. Dr. Katrina Lewis of Advanced PTSD Solutions in Great ...
- This is how employers can help support their veteran population suffering from PTSDon November 22, 2021 at 10:00 am
Veterans seeking treatment for mental health challenges cited barriers to accessing healthcare services, including transportation and finding nearby providers with experience treating PTSD.
- Post-Covid Stress Disorder: Signs, Treatment and Everything You Need to Knowon November 20, 2021 at 9:12 pm
Some symptoms of Post Covid Stress Disorder include headaches, anxiety, insomnia, lethargy, irritability, and mood changes, among others.
- How Psychedelic Drugs Are Helping Veterans and Others with PTSD, Depressionon November 19, 2021 at 7:04 pm
Experts say psychedelic drugs along with psychotherapy can help treat PTSD as well as depression and other mental health conditions.
via Bing News