Brain area tied to emotions is larger in vets, service members with mild TBI and PTSD
'An intriguing structural finding'
April 29, 2019
Science Daily/Veterans Affairs Research Communications
A new study finds that veterans and active-duty service members with combat-related PTSD and mild traumatic brain injury had larger amygdalas -- the region of the brain that processes such emotions as fear, anxiety, and aggression -- than those with only brain injuries.
The findings appeared online April 25 in the Journal of Head Trauma Rehabilitation.
Through magnetic resonance imaging, the researchers found that the right and left sides of the amygdala in people with combat-related PTSD and mild traumatic brain injury (mTBI) were larger than those in people with only combat-related mTBI. The amygdala is an almond-shaped section of tissue in the temporal portion of the brain and is key to triggering PTSD symptoms.
The researchers caution that the findings were based on an observational study and therefore can't prove a cause-and-effect relationship -- only a correlation.
The study included 89 veterans and active-duty military personnel, about a third of whom had both PTSD and mTBI. The rest formed the mild-TBI-only control group. A mild traumatic brain injury is also known as a concussion.
"This is an intriguing structural finding, given the role of the amygdala in the challenging [neuropsychological] symptoms witnessed in casualties of combat-related mTBI and PTSD," the researchers write. "Further investigation is needed to determine whether amygdala size could be used to screen people at risk for PTSD, or whether it could be used to monitor the [effectiveness of medical solutions]."
The study's lead author, Dr. Mingxiong Huang, is a neuroimaging scientist at the VA San Diego Health Care System. He says the finding of a larger amygdala in veterans with combat-related PTSD and mTBI was a bit of a surprise.
"Some previous PTSD research showed declines in amygdala volume based on the assumption of a loss of size due to injuries," says Huang, also a professor in the department of radiology at the University of California San Diego (UCSD). "Our finding of increased amygdala volume seems to point to different mechanisms, such as an exposure to repetitive fear and stress."
Such exposure, he adds, may lead to an abnormal growth of the neural networks within the amygdala, a development that has been reported in animal studies but hasn't been fully explored in human PTSD studies. More studies involving people with non-combat PTSD are needed to generalize this finding to other types of PTSD, he notes.
A co-author of the paper, Dr. Douglas Chang, is a physician and researcher at VA San Diego.
"The amygdala is involved with processing threat perception and arousal and with linking emotion to experience in complex ways," says Chang, who is also a professor of orthopedic surgery at UCSD. "A larger amygdala volume may be a sign of hyperactivity with an enlarged neural network. But we don't know whether this is an attempt by the brain to cope with PTSD or whether the growth and enlargement is causing symptoms, like an electrical storm."
He adds: "The situation may also resemble scar tissue formation on skin. Is this an organized response by the body to heal itself, or is the scar tissue going haywire and forming a grossly disfigured area? Another possibility is that this study simply identified at-risk people for PTSD with a pre-existing condition: an enlarged amygdala."
Combat-related PTSD and mTBI are leading health care concerns in veterans and service members. It's not unusual for both conditions to occur in the same person, based on evidence from a cross section of studies. Some of the symptoms are similar, such as depression, anxiety, insomnia, fatigue, and changes in memory and concentration. However, the effects of PTSD and mTBI on neural pathways in the brain, as well as the impact of the co-existence of the two, are not fully understood.
Scientists in Huang's study conducted the testing at VA San Diego and at two Marine Corps bases in California. They measured intracranial volume, a key statistic used to analyze the size of the brain and brain regions, especially in cases of neurodegenerative diseases.
The size of the right amygdala was 0.122 percent of total brain volume, on average, in the group with mTBI and PTSD. It was 0.115 percent in the cohort with only mTBI. The size of the left amygdala was 0.118 percent of brain volume in those with mTBI and PTSD, compared with 0.112 percent in the mTBI group. The researchers found both of those differences to be "statistically significant."
The study team also examined the caudate, the hippocampus, the anterior cingulate cortex, and the cerebral cortex. Those brain regions, like the amygdala, are in the limbic system, which controls basic emotions, including fear, pleasure, and anger. The researchers found no "statistically significant" differences in those regions, suggesting that only changes in the amygdala are linked to PTSD symptoms in people with mTBI, according to Chang.
The study authors say the findings have several implications for research and treatment.
"To be able to see a structural difference between these two cohorts and in this stage of PTSD really points to something going on with the amygdala," Chang says. "Can we use this as a screening tool to identify people at risk? Maybe this is an adaptive response that we can monitor and use to track different kinds of mental health treatment approaches. Maybe yoga is helpful, maybe mindfulness meditation is helpful, maybe exercise is helpful. Perhaps there are drugs that can protect somebody against these traumas or to help improve their conditions. To be able to identify something that's changed in a quantitative way is amazing. It opens the door to many possibilities to help treat this problem."
https://www.sciencedaily.com/releases/2019/04/190429182805.htm
Brain changes seen in veterans with PTSD after mindfulness training
Surprising findings suggest promise of mind-body techniques; more study needed
April 1, 2016
Science Daily/University of Michigan Health System
Like an endlessly repeating video loop, horrible memories plague people with post-traumatic stress disorder. But a new study in veterans shows the promise of mindfulness training for enhancing the ability to manage those thoughts if they come up, and not get 'stuck'. It also shows the veterans' brains changed in ways that may help them find their own off switch for that endless loop.
But a new study in veterans with PTSD shows the promise of mindfulness training for enhancing the ability to manage those thoughts if they come up, and not get "stuck." Even more surprising, it actually shows the veterans' brains changed -- in ways that may help them find their own off switch for that endless loop.
The findings, published in Depression and Anxiety by a team from the University of Michigan Medical School and VA Ann Arbor Healthcare System, come from a study of 23 veterans of the wars in Iraq and Afghanistan. All of them got some form of group therapy. After four months of weekly sessions, many reported that their PTSD symptoms eased up.
But only in those who got mindfulness training -- a mind-body technique that focuses on in-the-moment attention and awareness -- did the researchers see the brain changes that surprised even them.
Shifting brain connections
The changes showed up on functional MRI, or fMRI, brain scans that can visualize brain activity as different areas of the brain "talk" to one another through networks of connections between brain cells.
Before the mindfulness training, when the veterans were resting quietly, their brains had extra activity in regions involved in responding to threats or other outside problems. This is a sign of that endless loop of hypervigilance often seen in PTSD.
But after learning mindfulness, they developed stronger connections between two other brain networks: the one involved in our inner, sometimes meandering, thoughts, and the one involved in shifting and directing attention.
"The brain findings suggest that mindfulness training may have helped the veterans develop more capacity to shift their attention and get themselves out of being "stuck" in painful cycles of thoughts," says Anthony King, Ph.D., a U-M Department of Psychiatry researcher who led the new study in collaboration with VA psychologists.
"We're hopeful that this brain signature shows the potential of mindfulness to be helpful for managing PTSD for people who might initially decline therapy involving trauma processing," he adds. "We hope it may provide emotional regulation skills to help bring them to a place where they feel better able to process their traumas."
King, who has experience providing individual and group therapy for veterans from many conflicts, worked with a team of brain-imaging experts and PTSD specialists including senior author Israel Liberzon, M.D. They used an fMRI scanner at the VA Ann Arbor that's dedicated to research.
In all, 14 of the veterans finished the mindfulness sessions and completed follow-up fMRI scans, and 9 finished the comparison sessions and had scans. The small size of the group means the new results are only the start of an exploration of this issue, King says.
A palatable option
Before they launched the study, the researchers weren't sure that they could find enough veterans to try mindfulness-based training. After all, it has a reputation as an "alternative" approach and has a relationship to traditionally East and South Asian practices like meditation and yoga.
But in fact, more of the initial group of veterans stuck with mindfulness-based therapy sessions -- held each week for two hours with a trained mindfulness teacher and psychotherapist -- than made it all the way through the comparison psychotherapy group that didn't get mindfulness training.
"Once we explained the rationale behind mindfulness, which aims to ground and calm a person while also addressing mental phenomena, they were very interested and engaged -- more than we expected," says King. "The approach we took included standard elements of exposure therapy as well as mindfulness, to help lead veterans to be able to process the trauma itself."
The comparison group received a VA-developed intervention that was designed for "control group" use. It included problem-solving and group support but not mindfulness or exposure therapy.
The mindfulness group saw improvement in PTSD symptoms, in the form of decreased scores on a standard scale of PTSD severity, that was statistically significant and considered clinically meaningful, whereas the control group did not. However, the between-group effects in this small study were not considered statistically significant, and therefore King wants to explore the trend further in larger groups, and in civilians.
He emphasizes that people with PTSD should not see mindfulness alone as a potential solution for their symptoms, and that they should seek out providers trained specifically in PTSD care.
That's because mindfulness sessions can sometimes actually trigger symptoms such as intrusive thoughts to flare up. So, it is very important for people with PTSD to have help from a trained counselor to use mindfulness as part of their therapy for PTSD.
"Mindfulness can help people cope with and manage their trauma memories, explore their patterns of avoidance when confronting reminders of their trauma, and better understand their reactions to their symptoms," says King. "It helps them feel more grounded, and to notice that even very painful memories have a beginning, a middle and an end -- that they can become manageable and feel safer. It's hard work, but it can pay off."
Network shifts
At the start of the study, and in previous U-M/VA work, the fMRI scans of veterans with PTSD showed unusual activity. Even when they were asked to rest quietly and let their minds wander freely, they had high levels of activity in brain networks that govern reactions to salient, or meaningful, external signals such as threats or dangers. Meanwhile, the default mode network, involved in inwardly focused thinking and when the mind is wandering, was not as active in them.
But at the end of the mindfulness course, the default mode area was more active -- and showed increased connections to areas of the brain known as the executive network. This area gets involved in what scientists call volitional attentional shifting -- purposefully moving your attention to think about or act upon something.
Those with the greatest easing of symptoms had the largest increases in connections.
"We were surprised by the findings, because there is thinking that segregation between the default mode network and the salience network is good," says King. "But now we are hopeful that this brain signature of increased connection to areas associated with volitional attention shifting at rest may be helpful for managing PTSD, and may help patients have more capacity to help themselves get out of being stuck in painful ruts of trauma memories and rumination."
https://www.sciencedaily.com/releases/2016/04/160401073703.htm