How experiencing traumatic stress leads to aggression
Strengthened amygdala pathways increase aggression, may be targets for PTSD treatment
May 18, 2020
Science Daily/Society for Neuroscience
Traumatic stress can cause aggression by strengthening two brain pathways involved in emotion, according to research recently published in JNeurosci. Targeting those pathways via deep brain stimulation may stymie aggression associated with post-traumatic stress disorder.
The consequences of traumatic stress linger long after the stress ends. People suffering from post-traumatic stress disorder often display heightened aggression, caused by unknown changes in the amygdala. An almond-shaped structure nestled deep inside the brain, the amygdala plays an essential role in emotion, social behaviors, and aggression.
Nordman et al. examined how different amygdala circuits changed in male mice after traumatic stress. Two connections strengthened, resulting in more attacks on other mice: the circuitry connecting the amygdala to the ventromedial hypothalamus and the bed nucleus of the stria terminalis. The former modulates the frequency of attacks, while the latter controls the length of attacks. The research team then used low frequencies of light to stop the pathways from strengthening, preventing an increase in aggressive behavior. Deep brain stimulation may elicit the same effect in humans.
https://www.sciencedaily.com/releases/2020/05/200518145022.htm
Research leads to life changing improvement for some people living with depression
Deep brain stimulation study targets people with treatment-resistant depression
January 27, 2020
Science Daily/University of Calgary
Researchers have completed a study investigating the effects of two different methods of deep brain stimulation (DBS), short pulse and long pulse, for treatment-resistant depression. The findings showed that both methods of stimulation were equally safe and effective in reducing depressive symptoms. Some study participants have experienced a massive positive change in their lives.
Beth MacKay knew at a young age that she saw the world differently than many of her friends and family. She thought her pessimism and cynicism were rooted in realism, a proud reminder of her Scottish roots, and not a sign of an underlying medical condition. But, that understanding of herself changed when at the age of 17, she attempted suicide.
"I was diagnosed with depression, but looking back, it started much earlier," says MacKay, now 31. "Doctors believe it may have started when I was 10 or 11-years-old. As a child I would go through periods where I couldn't sleep, I didn't want to go to school, and I was constantly sick."
MacKay's parents tried to find help and support for her. They thought her symptoms may have been related to a learning disorder, but no one suspected depression could be the cause.
Prescribed anti-depressants and therapy, MacKay went on to university. She noticed everyone around her seemed to be functioning, but she couldn't get out of bed. She spent the next several years pretending to be okay. She would sleep most of the day, and get up-and-out only long enough to put on a front to show people she was fine. It seemed that no matter what treatment options she tried nothing made life manageable.
"Everyday felt like climbing up a mountain. Something as simple as showering, doing dishes or throwing in a load of a laundry felt too difficult at times," recalls MacKay.
Always open to trying something else to improve her life, MacKay volunteered for a research study at the University of Calgary. Dr. Rajamannar Ramasubbu, MD, was investigating the effects of two different methods of deep brain stimulation (DBS), short pulse and long pulse, for treatment-resistant depression.
"It can be very difficult to find study participants for research like this," says Ramasubbu, a professor in the departments of Psychiatry and Clinical Neurosciences, and member of The Mathison Centre for Mental Health Research & Education and the Hotchkiss Brain Institute at the Cumming School of Medicine (CSM). "The procedure is invasive, so many clinicians are reluctant to recommend it. It requires implanting an electrode into the brain that is connected to a pulse generator that is implanted under the clavicle into the chest."
Just as pacemakers deliver electrical impulses to help control abnormal heart rhythms, DBS devices deliver electrical impulses to help neurons (brain cells) within the brain communicate more efficiently with each other.
"Depression is caused by abnormalities in the neural circuit responsible for emotional regulation," says Ramasubbu. "The region of the brain we target (subcallosal cingulate) is the junction of the limbic and frontal regions. Stimulating this area helps to keep a balance between these two unique systems."
Multi-disciplinary team collaborates on DBS study
Participants are awake when the device is implanted. Dr. Zelma Kiss, MD/PhD, a neurosurgeon and co- principal investigator of the study performed the procedure at the Foothills Medical Centre (FMC).
Participants were randomized into two groups, one group received short pulse stimulation, the other long pulse width stimulation. After six months, treatment switched for those who did not respond in the first six months. Researchers used the Hamilton Depression Rating Scale to measure change in symptoms.
"Both methods of stimulation were equally safe and effective in reducing depressive symptoms," says Ramasubbu. "50 per cent of the participants responded to the stimulation with 50 per cent reduction in symptoms. Of which 30 per cent experienced complete improvement in their symptoms, especially those who received long pulse width stimulation."
MacKay says she's experienced a massive change. "Basically I was nearly dead and now I'm mostly alive. I'm still figuring out what life feels like, because it feels so different and so much better than before the implant."
Ramasubbu adds more research is needed to determine which patients with treatment resistant depression will benefit from DBS. Study participants ranged in age from 20 to 70, with younger participants showing better improvement than older participants.
https://www.sciencedaily.com/releases/2020/01/200127164325.htm
Brain stimulation for PTSD patients
Sweat response can make stimulators responsive
August 7, 2019
Science Daily/University of Houston
Electrical engineers report that the tiny beads of sweat, which appear in patients experiencing PTSD or other neuropsychiatric disorders can be measured and used to design and more responsive brain stimulator for therapy.
For 8-million adults who suffer from post-traumatic stress disorder in any given year, medication and cognitive therapy have been the treatment protocol. Now, University of Houston assistant professor of electrical engineering Rose T. Faghih is reporting in Frontiers in Neuroscience that a closed-loop brain stimulator, based on sweat response, can be developed not only for PTSD patients, but also for those who suffer an array of neuropsychiatric disorders.
"Sweat primarily helps maintain body temperature; however, tiny bursts of sweat are also released in response to psychologically arousing stimuli. Tracking the associated changes in the conductivity of the skin, which can be seamlessly measured using wearables in real-world settings, thus provides a window into a person's emotions," reports Faghih.
For people with movement disorders like Parkinson's disease and essential tremor, who have not responded to medication, application of high-frequency electric current to the brain, or deep brain stimulation, is regarded as most effective. Electrodes are placed in certain areas of the brain to regulate abnormal functions and a pacemaker-like device, placed in the upper chest, controls the amount of stimulation the brain receives. Open-loop stimulators, the most widely-used, deliver continuous stimulation until manually re-adjusted by a physician. Closed-loop stimulators, which provide stimulation in response to biomarkers of pathologic brain activity, have been developed for movement disorders, but are yet to be explored for the treatment of neuropsychiatric disorders.
Signaling the onset of a PTSD episode, skin develops the tiniest sheen of perspiration. That symptom of the body's fight or flight response signals a change in the skin's electrical conductivity and provides a window into the brain's state of emotional arousal. Using skin conductance to create the framework for a deep brain stimulator seemed logical to Faghih after reviewing group studies of Vietnam combat veterans with PTSD. Among the findings, PTSD subjects had the largest skin conductance responses when confronted with combat-related words. In a similar study comparing Vietnam combat veterans with and without PTSD and non-combat controls, PTSD veterans had the highest baseline skin conductance levels.
"Skin conductance additionally has the advantage of being easily measured with wearable devices that afford convenience, seamless integration into clothing and do not involve risk of surgically implanted sensors," said Faghih.
The ultimate goal will be to develop closed-loop prototypes that can eventually be used for treating patients in a variety of neuropsychiatric disorders. Faghih's graduate researchers Dilranjan Wickramasuriya and Md. Rafiul Amin were first and second authors, respectively, of the article.
https://www.sciencedaily.com/releases/2019/08/190807105630.htm