How does post-traumatic stress disorder change the brain?

Child abuse. Rape. Sexual assault. Brutal physical attack. Being in a war and witnessing violence, bloodshed, and death from close quarters. Near death experiences. These are extremely traumatic events, and some victims bear the scars for life.
The physical scars heal, but some emotional wounds stop the lives of these people dead in their tracks. They are afraid to get close to people or form new relationships. Change terrifies them, and they remain forever hesitant to express their needs or give vent to their creative potential. It may not be always apparent, but post-traumatic stress disorder (PTSD) stifles the life force out of its victims. It is no use telling them to “get over” it because PTSD fundamentally changes the brain’s structure and alters its functionalities.

What goes on inside the brains of people with PTSD?
PTSD is painful and frightening. The memories of the event linger and victims often have vivid flashbacks. Frightened and traumatized, they are almost always on edge and the slightest of cues sends them hurtling back inside their protective shells. Usually victims try to avoid people, objects, and situations that remind them of their hurtful experiences; this behavior is debilitating and prevents them from living their lives meaningfully. 

Many victims forget the details of the incident, obviously in an attempt to lessen the blow. But this coping mechanism has negative repercussions as well. Without accepting and reconciling with “reality,” they turn into fragmented souls.

Extensive neuroimaging studies on the brains of PTSD patients show that several regions differ structurally and functionally from those of healthy individuals. The amygdala, the hippocampus, and the ventromedial prefrontal cortex play a role in triggering the typical symptoms of PTSD. These regions collectively impact the stress response mechanism in humans, so the PTSD victim, even long after his experiences, continues to perceive and respond to stress differently than someone who is not suffering the aftermaths of trauma.

Effect of trauma on the hippocampus
The most significant neurological impact of trauma is seen in the hippocampus. PTSD patients show a considerable reduction in the volume of the hippocampus. This region of the brain is responsible for memory functions. It helps an individual to record new memories and retrieve them later in response to specific and relevant environmental stimuli. The hippocampus also helps us distinguish between past and present memories.

PTSD patients with reduced hippocampal volumes lose the ability to discriminate between past and present experiences or interpret environmental contexts correctly. Their particular neural mechanisms trigger extreme stress responses when confronted with environmental situations that only remotely resemble something from their traumatic past. This is why a sexual assault victim is terrified of parking lots because she was once raped in a similar place. A war veteran still cannot watch violent movies because they remind him of his trench days; his hippocampus cannot minimize the interference of past memories.

Effect of trauma on the ventromedial prefrontal cortex
Severe emotional trauma causes lasting changes in the ventromedial prefrontal cortex region of the brain that is responsible for regulating emotional responses triggered by the amygdala. Specifically, this region regulates negative emotions like fear that occur when confronted with specific stimuli. PTSD patients show a marked decrease in the volume of ventromedial prefrontal cortex and the functional ability of this region. This explains why people suffering from PTSD tend to exhibit fear, anxiety, and extreme stress responses even when faced with stimuli not connected – or only remotely connected – to their experiences from the past.

Effect of trauma on the amygdala
Trauma appears to increase activity in the amygdala. This region of the brain helps us process emotions and is also linked to fear responses. PTSD patients exhibit hyperactivity in the amygdala in response to stimuli that are somehow connected to their traumatic experiences. They exhibit anxiety, panic, and extreme stress when they are shown photographs or presented with narratives of trauma victims whose experiences match theirs; or made to listen to sounds or words related to their traumatic encounters.

What is interesting is that the amygdala in PTSD patients may be so hyperactive that these people exhibit fear and stress responses even when they are confronted with stimuli not associated with their trauma, such as when they are simply shown photographs of people exhibiting fear.
The hippocampus, the ventromedial prefrontal cortex, and the amygdala complete the neural circuitry of stress. The hippocampus facilitates appropriate responses to environmental stimuli, so the amygdala does not go into stress mode. The ventromedial prefrontal cortex regulates emotional responses by controlling the functions of the amygdala. It is thus not surprising that when the hypoactive hippocampus and the functionally-challenged ventromedial prefrontal cortex stop pulling the chains, the amygdala gets into a tizzy.

Hyperactivity of the amygdala is positively related to the severity of PTSD symptoms. The aforementioned developments explain the tell-tale signs of PTSD—startle responses to the most harmless of stimuli and frequent flashbacks or intrusive recollections.

Researchers believe that the brain changes caused by PTSD increase the likelihood of a person developing other psychotic and mood disorders. Understanding how PTSD alters brain chemistry is critical to empathize with the condition of the victims and devise treatment methods that will enable them to live fully and fulfill their true potential.

But in the midst of such grim findings, scientists also sound a note of hope for PTSD patients and their loved ones. According to them, by delving into the pathophysiology of PTSD, they have also realized that the disorder is reversible. The human brain can be re-wired. In fact, drugs and behavioral therapies have been shown to increase the volume of the hippocampus in PTSD patients. The brain is a finely-tuned instrument. It is fragile, but it is heartening to know that the brain also has an amazing capacity to regenerate.

http://brainblogger.com/2015/01/24/how-does-post-traumatic-stress-disorder-change-the-brain/

Hundreds of genes seen sparking to life two days after death!

The discovery that many genes are still working up to 48 hours after death has implications for organ transplants, forensics and our very definition of death!

When a doctor declares a person dead, some of their body may still be alive and kicking – at least for a day or two. New evidence in animals suggests that many genes go on working for up to 48 hours after the lights have gone out.

This hustle and bustle has been seen in mice and zebrafish, but there are hints that genes are also active for some time in deceased humans. This discovery could have implications for the safety of organ transplants as well as help pathologists pinpoint a time of death more precisely, perhaps to within minutes of the event.
 

Peter Noble and Alex Pozhitkov at the University of Washington, Seattle, and their colleagues investigated the activity of genes in the organs of mice and zebrafish immediately after death. They did this by measuring the amount of messenger RNA present. An increase in this mRNA – which genes use to tell cells to make products such as proteins – indicates that genes are more active.

As you might expect, overall mRNA levels decreased over time. However, mRNA associated with 548 zebrafish genes and 515 mouse genes saw one or more peaks of activity after death. This meant there was sufficient energy and cellular function for some genes to be switched on and stay active long after the animal died.

These genes cycled through peaks and dips in activity in a “non-winding down” manner, unlike the chaotic behaviour of the rest of the decaying DNA, says Noble.
Hundreds of genes with different functions “woke up” immediately after death. These included fetal development genes that usually turn off after birth, as well as genes that have previously been associated with cancer. Their activity peaked about 24 hours after death.

A similar process might occur in humans. Previous studies have shown that various genes, including those involved in contracting heart muscle and wound healing, were active more than 12 hours after death in humans who had died from multiple trauma, heart attack or suffocation (Forensic Science International, doi.org/bj63).

The fact that some genes associated with cancer are activated after death in animals, might be relevant for reducing the incidence of cancer in people who receive organ transplants, says Noble. People who get a new liver, for example, have more cancers after the treatment than you would expect if they hadn’t had a transplant. The regime of drugs they need to take for life to suppress their immune system so it doesn’t attack the new organ may contribute to this, but Noble says it is worth investigating if activated cancer genes in the donor liver could play a part.

So why do so many genes wake up after death? It is possible that many of the genes become active as part of physiological processes that aid healing or resuscitation after severe injury. For example, after death, some cells might have enough energy to kick-start genes involved in the inflammation process to protect against damage – just as they would if the body were alive. Alternatively, a rapid decay of genes that normally suppress other genes – such as those involved in embryological development – might allow the usually quiet genes to become active for a short period of time.

For forensic scientists, knowing how gene activity rises and falls at different time points after death is useful for working out when someone died. Measuring mRNA would allow us to nail down the time since death to hours and possibly even minutes, rather than days, helping to reconstruct events surrounding the death.

It is good to see such progress being made in this area, says Graham Williams, consultant forensic geneticist at the University of Huddersfield, UK. “But substantial work is required before this could be applied to case work.” The research also raises important questions about our definition of death – normally accepted as the cessation of a heartbeat, brain activity and breathing. If genes can be active up to 48 hours after death, is the person technically still alive at that point? “Clearly, studying death will provide new information on the biology of life,” says Noble.

https://www.newscientist.com/article/2094644-hundreds-of-genes-seen-sparking-to-life-two-days-after-death/