Stress is inherent in every human being. It is the
way we respond to a real or imaginary threat. It is the fight-or-flight
mechanism which enables our bodies to initiate the chain of biochemical
reactions in response to a hazard, whether real or perceived. While your mind
and emotions develop through the learning experience of life, instincts were
given to you as a survival protection tool.
What is stress?
Stress is a normal physical response to events that
make you feel threatened or upset your balance in some way. When you sense
danger – whether it’s real or imagined – the body's defenses kick into high
gear in a rapid, automatic process known as the “fight-or-flight” reaction, or
the stress response.
When you perceive a threat, your nervous system
responds by releasing a flood of stress hormones, including adrenaline and
cortisol. These hormones rouse the body for emergency action.
Your heart pounds faster, muscles tighten, blood
pressure rises, breath quickens, and your senses become sharper. These physical
changes increase your strength and stamina, speed your reaction time, and
enhance your focus – preparing you to either fight or flee from the danger at
hand.
The stress response is the body’s way of protecting
you. When working properly, it helps you stay focused, energetic, and alert. In
emergency situations, stress can save your life – giving you extra strength to
defend yourself, for example, or spurring you to slam on the brakes to avoid an
accident.
The stress response also helps you rise to meet
challenges. Stress is what keeps you on your toes during a presentation at
work, sharpens your concentration when you’re attempting the game-winning free
throw, or drives you to study for an exam when you'd rather be watching TV.
But beyond a certain point, stress stops being
helpful and starts causing major damage to your health, your mood, your
productivity, your relationships, and your quality of life.
Chronic
Stress Danger
What happens with chronic stress then? If we are
chronically stressed and experience chronic distress as a result, then we are
constantly releasing cortisol. Like red wine, too much of a good thing can be
bad. Chronically high cortisol has been shown to cause brain cell dysfunction,
to kill brain cells, and to cause atrophy of the brain.
With aging, something additional happens. Biological
systems become deregulated. Our ability to shut down biological systems once
they are turned on becomes impaired with aging. Cortisol levels go up, but they
stay up longer and go down slower. We become more prone to the psychological effects
of stress if we are distressed, and the effects last longer. More brain cells
may dysfunction and more may be killed.
Over the course of a lifetime, the effects of chronic stress can accumulate and become a risk factor for cognitive decline and Alzheimer's disease. Several studies have shown that stress, and particularly one's individual way of reacting to stress (the propensity to become distressed often found in neurotic people for example), increases the risk for Alzheimer's disease.
Clinical
Research – Stress as Risk Factor for Alzheimer’s Disease
UC
San Diego Study, 2010
In 2010, a research group led by Mark Tuszynski at
the University of California, San Diego, performed a study on monkeys to see
how different environments affect the development of Alzheimer’s disease. Some
monkeys were put in very small cages when they were young, while others were in
larger cages. The monkeys in the small cages were unable to get enough exercise
and released larger amounts of stress hormones. These stress hormones can
reduce the number of nerve synapses. Upon study of the monkeys’ brains, it was
confirmed that monkeys raised in smaller cages had, on average, a higher
density of plaques and lower number of synapses, the same brain pathology seen
postmortem in Alzheimer’s patients.
University
of Houston, 2010
In another study in March, 2010, Karim Alkadhi at
the University of Houston led a research team to study the effects of stress on
rodents in a water maze. Some rats were injected with amyloid peptides, while
other rats were subjected to stress by placing an intruder rat in their home
cage. The rats were divided into 4 groups to see the effects of the amyloid
proteins and stress singly and combined.
The study results showed that only one group of
students had difficulty learning the new task, reflecting substantial memory
impairment - the animals that received both the amyloid dose and were regularly
stressed out.”
Utah
State University, 2010
Chronic psychological stress throughout a lifespan
might increase an individual's risk for Alzheimer's and dementia later in life,
according to research from the Emma Eccles Jones College of Education and Human
Services at Utah State University.
The research, led by Maria Norton, Ph.D., built off
the recently completed 15-year Cache County Memory Study (CCMS) and used that
data to focus on the role psychological stress has on dementia. The findings
are consistent with the hypothesis that chronic stress can expose an individual
to long-term levels of stress-related hormones, which results in chronically
high levels of glucocorticoids, a natural chemical, shown in both animal and
human studies to increase the rate of neuronal cell death with long-term
exposure.
"Using this objective data, such as death
records, medical information, and the cognitive evaluations from the CCMS, we
were able to see that people who experienced particularly stressful life
events, such as a parent's death during one's childhood, death of a child or
spouse, or living with a spouse who is afflicted with dementia is associated
with significantly higher rates of dementia later in life," Norton said.
Norton also found that there were some factors that
were associated with lower rates of depression and stress, such as individuals
who had high levels of religious involvement, thus indicating that the ability
to cope with psychological adversity might reduce the risk of Alzheimer's.
University
of South California, 2011
While there were multiple studies, which confirmed
the causal relationship between chronic stress and Alzheimer’s Disease
development, scientists at the University of Southern California (USC) have now
found an scientifically backed up mechanism: chronic stress (physical or
mental) causes over expression of the RCAN1 gene, in turn leading to
neurodegenerative disease.
The mechanism involves the following steps:
- In a
healthy person, the RCAN1 gene helps cells cope with stress. However, chronic
overproduction of RCAN1 causes hyperphosphorylation of tau proteins in the
brain.
- Tau
proteins stabilize microtubules, which are like scaffolding, used to build
the brain’s neurons. Previous research has shown that when the tau protein
binds too much phosphate (hyperphosphorylation), it forms snarls that
prevent the brain’s signals from effectively traveling.
- These
neurofibrillary tangles eventually choke the life out of neurons, killing
off brain function a tiny piece at a time in what is outwardly recognized
as degenerative brain disease.
The researchers suggests that overexpression of
RCAN1 is also connected to Amyloid beta (overproduction of the Amyloid beta
peptide), a competing theory of neurodegeneration.
Further supporting the RCAN1 role are observations
that it has been also shown to be chronically overexpressed from birth in the
brains of patients with Down syndrome. These patients develop neurofibrillary
tangles and typically start to experience the onset of Alzheimer’s disease
around age 40.
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