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Post-traumatic Stress Disorder May Increase the Risk for Dementia
Dementia is a broad term that covers several types of neurodegenerative disorders which affect a person’s ability to think, learn, recall memories, and perform everyday activities. This deterioration of the brain’s cognitive function is not considered part of the normal process of aging and it affects more than 47 million people worldwide, with 7.7 million new cases every year.
Alzheimer’s disease (AD) is the most common cause of dementia, contributing to 60-70% of cases and has a significant social and economical impact. Evidence suggests that changes on the molecular level that contribute to the development of the disease can occur as far back as 25 years prior to any noticeable symptoms.
Source: Alzheimer’s Association
Recently, researchers have been exploring the connection between AD and post‐traumatic stress disorder (PTSD). Epidemiological data shows that people with PTSD at a young age have an increased risk of developing AD in old age. A study from 2010, looked at data from 181,093 U.S. veterans and found that those diagnosed as having PTSD were nearly 2 times more likely to develop dementia compared with those without PTSD.
People with PTSD have an impaired mechanism, called fear extinction, that causes them to continue having a stress response to a stimulus that is no longer a threat. Normally, through processes like cognitive flexibility and extinction learning the individual would stop having such a response to the stimulus that once caused the traumatic event.
In a recently published study, scientists aimed to discover some of the mechanisms that link PTSD and AD. They observed that age‐associated memory decline is most likely a direct consequence of the reduced expression of a gene called Formin 2 (FMN2). Loss of FMN2 in young mice caused PTSD-like symptoms and also led to accelerated age-associated memory decline. In the tested mice deficits in fear extinction preceded the impairment of memory consolidation.
FMN2 has been associated with intellectual disability and is essential for extinction learning and cognitive flexibility. Both PTSD patients and AD patients have been shown to have a decreased FMN2 expression. The researchers determined that FMN2 levels are altered in blood samples from PTSD patients which may indicate that exposure to PTSD‐inducing events may alter FMN2 levels in the brain.
The link between dementia and PTSD has also been highlighted in another recent study, where researchers caution that delayed-onset post-traumatic symptoms in older people may be misdiagnosed as part of the symptoms of dementia.
Dr. Tarun Kuruvilla, senior author of the Progress in Neurology & Psychiatry review said:
“Every patient with dementia has a unique narrative, which if captured in the earlier stages of the disease, enables clinicians and their families to understand the origin of their distress. Therefore, it is important to look for a history of previous trauma in patients with BPSD as this could be due to delayed onset PTSD.”
A Mercury-bound spacecraft's noisy flyby of our home planet.
- There is no sound in space, but if there was, this is what it might sound like passing by Earth.
- A spacecraft bound for Mercury recorded data while swinging around our planet, and that data was converted into sound.
- Yes, in space no one can hear you scream, but this is still some chill stuff.
First off, let's be clear what we mean by "hear" here. (Here, here!)
Sound, as we know it, requires air. What our ears capture is actually oscillating waves of fluctuating air pressure. Cilia, fibers in our ears, respond to these fluctuations by firing off corresponding clusters of tones at different pitches to our brains. This is what we perceive as sound.
All of which is to say, sound requires air, and space is notoriously void of that. So, in terms of human-perceivable sound, it's silent out there. Nonetheless, there can be cyclical events in space — such as oscillating values in streams of captured data — that can be mapped to pitches, and thus made audible.
Image source: European Space Agency
The European Space Agency's BepiColombo spacecraft took off from Kourou, French Guyana on October 20, 2019, on its way to Mercury. To reduce its speed for the proper trajectory to Mercury, BepiColombo executed a "gravity-assist flyby," slinging itself around the Earth before leaving home. Over the course of its 34-minute flyby, its two data recorders captured five data sets that Italy's National Institute for Astrophysics (INAF) enhanced and converted into sound waves.
Into and out of Earth's shadow
In April, BepiColombo began its closest approach to Earth, ranging from 256,393 kilometers (159,315 miles) to 129,488 kilometers (80,460 miles) away. The audio above starts as BepiColombo begins to sneak into the Earth's shadow facing away from the sun.
The data was captured by BepiColombo's Italian Spring Accelerometer (ISA) instrument. Says Carmelo Magnafico of the ISA team, "When the spacecraft enters the shadow and the force of the Sun disappears, we can hear a slight vibration. The solar panels, previously flexed by the Sun, then find a new balance. Upon exiting the shadow, we can hear the effect again."
In addition to making for some cool sounds, the phenomenon allowed the ISA team to confirm just how sensitive their instrument is. "This is an extraordinary situation," says Carmelo. "Since we started the cruise, we have only been in direct sunshine, so we did not have the possibility to check effectively whether our instrument is measuring the variations of the force of the sunlight."
When the craft arrives at Mercury, the ISA will be tasked with studying the planets gravity.
The second clip is derived from data captured by BepiColombo's MPO-MAG magnetometer, AKA MERMAG, as the craft traveled through Earth's magnetosphere, the area surrounding the planet that's determined by the its magnetic field.
BepiColombo eventually entered the hellish mangentosheath, the region battered by cosmic plasma from the sun before the craft passed into the relatively peaceful magentopause that marks the transition between the magnetosphere and Earth's own magnetic field.
MERMAG will map Mercury's magnetosphere, as well as the magnetic state of the planet's interior. As a secondary objective, it will assess the interaction of the solar wind, Mercury's magnetic field, and the planet, analyzing the dynamics of the magnetosphere and its interaction with Mercury.
Recording session over, BepiColombo is now slipping through space silently with its arrival at Mercury planned for 2025.
Erin Meyer explains the keeper test and how it can make or break a team.
- There are numerous strategies for building and maintaining a high-performing team, but unfortunately they are not plug-and-play. What works for some companies will not necessarily work for others. Erin Meyer, co-author of No Rules Rules: Netflix and the Culture of Reinvention, shares one alternative employed by one of the largest tech and media services companies in the world.
- Instead of the 'Rank and Yank' method once used by GE, Meyer explains how Netflix managers use the 'keeper test' to determine if employees are crucial pieces of the larger team and are worth fighting to keep.
- "An individual performance problem is a systemic problem that impacts the entire team," she says. This is a valuable lesson that could determine whether the team fails or whether an organization advances to the next level.