Cerebellum Damage May Be the Root of PTSD in Combat Veterans

Cerebellum in red.

Source: Life Science Databases/Wikimedia Commons

A groundbreaking study by a team of brain injury experts has discovered that mild traumatic brain injury (mTBI) to the cerebellum may be a hidden cause of post-traumatic stress disorder (PTSD) in combat veterans—especially for soldiers who encountered explosive blasts in Iraq or Afghanistan.

Although the cerebellum (Latin for “little brain”) has traditionally been considered the part of our brain that integrates sensory information and coordinates movements, experts now believe that the cerebellum strongly influences our emotional states of mind.

Purkinje cell drawing by Ramón y Cajal circa 1899.

Source: Ramón y Cajal/Public Domain

The January 2016 study, “Repetitive Blast Exposure in Mice and Combat Veterans Causes Persistent Cerebellar Dysfunction,” was published in the journal Science Translational Medicine. This study, by researchers from VA Puget Sound Health Care System and the University of Washington, uncovers some mysteries of how combat veterans have been injured by repetitive blast exposure.

The researchers found that repeated exposure to blasts creates microlesions in the blood-brain barrier (BBB) and the ventral cerebellum. According to the researchers, Purkinje cell loss in the cerebellum associated with these BBB microlesions could be an important factor in driving long-term changes in the brain associated with PTSD experienced by combat veterans.

The researchers found that the number of blast exposures correlated directly with cerebellar dysfunction in combat veterans. Cerebellar is the sister word to cerebral and means, "of, relating to, or affecting the cerebellum." Interestingly, the pattern of damage observed in the Purkinje cells of combat veterans is similar to findings observed in retired boxers more than 40 years ago.

“Whatever the Cerebellum Is Doing, It’s Doing a Lot of It”

Source: Courtesy of Viking

My father, Richard M. Bergland, was a neuroscientist, neurosurgeon, and author of The Fabric of Mind (Viking). He was obsessed with the hidden powers of the cerebellum and passed this obsession on to me. The relationship between both hemispheres of the cerebrum (Latin for "brain") and both hemispheres of the cerebellum is the foundation of The Athlete’s Way paradigm of thought.

The cerebellum is only 10% of brain volume but holds over 50% of the total neurons in the brain. My dad always said, “We don’t know exactly what the cerebellum is doing, but whatever it’s doing, it’s doing a lot of it.” When my father passed away unexpectedly in 2007, I made a vow that I would continue his quest to solve the riddle of what exactly it is the cerebellum is doing.

I was excited this morning to wake up and read about the new study linking PTSD and the cerebellum for two reasons. Firstly, I've been writing a lot about the neuroscience of PTSD in the past week. Recently, I had a strong empathetic response to the personal testimonial of one of my Psychology Today readers who goes by the alias of 'Wounded Warrior.' He suffered TBI in Iraq and has been struggling to find effective treatments for his PTSD. Since hearing his story a few days ago, I've heightened my antennae for any new research that might be of help to him and other combat veterans.

Secondly, my father was labeled a heretic by many of his peers in the 'ivory tower' of the medical establishment when he spoke of the cerebellum possibly playing a role in our cognitive, creative, and emotional brain functions. My dad went to his grave not knowing that he'd been vindicated. Since his death, I’ve been on a personal crusade to clear my father’s name and reputation as a visionary and iconoclast for posterity.

Mild Traumatic Brain Injury (mTBI) of the Cerebellum May Contribute to PTSD

Both hemispheres of the cerebellum have extensive "microzones" that serve a variety of functions.

Source: Wikimedia Commons/Public Domain

A wide range of studies have shown that most veterans repeatedly exposed to mild-blast explosions suffered mild traumatic brain injuries (mTBIs). In fact, more than 250,000 U.S. military personnel around the world have been diagnosed with mTBI.

The new study on the cerebellum and mTBI found that the more blasts a soldier is exposed to, the more likely that soldier is to show chronic changes in the neuron activity of the cerebellum. The scientists also found that in mild blast-exposed mice, Purkinje cells are lost in the same region of the cerebellum as in combat veterans who have been exposed to blasts.

Post-Traumatic Stress Disorder Essential Reads

Taming the Amygdala in PTSD

What Happens In the Brain During PTSD?

In a press release, Dr. David Cook, VA scientist and UW research associate professor of medicine and pharmacology said,

"There is a huge gulf separating our understanding of what kind of brain injuries develop because of mild blast and how they relate to the neuroimaging changes many research groups have detected. The similarities we see in the pattern of neuron injury in the cerebellum of mice, the neuron loss previously seen in boxers, and our neuroimaging findings in veterans is a step toward reducing this knowledge gap.”

Dr. Elaine Peskind, co-director of the Mental Illness Research, Education, and Clinical Center at VA Puget Sound, was another author on this study. She describes TBI and PTSD as the “invisible wounds of war.”

Approximately 75% of the mTBI patients Peskind treats also have PTSD. In a press release, she said, "Problems with mood, irritability, and impulsivity are very common in our mTBI veterans. These findings suggest we should pay more attention to how mTBI affects the cerebellum if we want to fully understand the emotional difficulties experienced by veterans with mTBI."

Conclusion: We Need More Research on the Link Between TBI, PTSD, and the Cerebellum

First author of this study, Dr. James Meabon, is a VA scientist and UW acting assistant professor of psychiatry and behavioral sciences. He’s also a U.S. Army veteran infantryman who has dedicated his life's work to helping other veterans. Meabon concluded, "Something is going on with them that they don't understand and at this point, neither do we. We have a lot of work ahead, but these results are a step in the right direction.”

To read more about this topic, check out my Psychology Today blog posts,

• "The Cerebellum Deeply Influences Our Thoughts and Emotions"
• "How Does Your Cerebellum Counter "Paralysis By Analysis?""
• "Purkinje Cells Burst to Life With State-Dependent Excitation"
• "The Neuroscience of Fear Responses and Post-Traumatic Stress"
• "Two New PTSD Treatments Offer Hope for Veterans"
• "The Neuroscience of Post-Traumatic Stress Disorder"
• "'Surf Therapy' and Being in the Ocean Can Alleviate PTSD"
• "Meditation Reduces Post-Traumatic Stress Disorder Symptoms"
• "How Are Purkinje Cells in the Cerebellum Linked to Autism?"
• "Autism, Purkinje Cells, and the Cerebellum, Are Intertwined"
• "More Research Links Autism and the Cerebellum"
• "The Cerebellum May Be the Seat of Creativity"
• "Superfluidity: Decoding the Enigma of Cognitive Flexibility"
• "The Neurobiology of Grace Under Pressure"
• "How Does the Vagus Nerve Convey Gut Instincts to the Brain?"

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