Chronic Stress Damages Brain, Increases Risk of Dementia

People with chronic stress and anxiety are at an increased risk of developing depression and even dementia, a new research has shown.

When the researchers noticed that mental illness is aggravated by stress, they aimed to address the question of whether anxiety damages the brain and whether they could identify mechanisms behind the connection between stress and mental illness.

For their research, the tem - led by Dr. Linda Mah of the Rotman Research Institute at Baycrest Health Sciences in Canada reviewed animal and human studies that examined brain areas affected by chronic anxiety, fear and stress that are already published. They reported finding "extensive overlap" of the brain's neurocircuitry in all three conditions, which they said may justify the link between chronic stress and the development of neuropsychiatric disorders, including depression and Alzheimer's disease.

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Occasional and temporary fear and stress is normal part of life. This is common among people to feel stressed and anxious before a job interview or an exam. However, when these reactions become chronic or frequent, they can affect daily lives and interfere with work, school and relationships.

Chronic stress is a pathological state. It is caused by stress causing disruption on immune, metabolic and cardiovascular systems, which leads to decay of the brain's hippocampus (crucial for long-term memory and spatial navigation).

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Dr. Linda Mah, clinician scientist with Baycrest's Rotman Research Institute and lead author of the review said:

"Pathological anxiety and chronic stress are associated with structural degeneration and impaired functioning of the hippocampus and the prefrontal cortex (PFC), which may account for the increased risk of developing neuropsychiatric disorders, including depression and dementia.”

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Dr. Mah and colleagues focused on key structures in the neurocircuitry of fear and anxiety – amygdala, medial prefrontal cortex, hippocampus. These brain areas are impacted during chronic stress. The researchers noted similar patterns of abnormal brain activity with fear, anxiety and chronic stress – specifically an overactive amygdala (associated with emotional responses) and an under-active PFC (thinking areas of the brain that help regulate emotional responses through cognitive appraisal).

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This see-saw relationship was first identified in a landmark study by world-renowned neurologist and depression researcher Dr. Helen Mayberg over a decade ago.

However, Dr. Mah also suggests that damage to the hippocampus and PFC as a result of stress can be reversible. She said that both anti-depressant treatment and physical activity have both shown promise in increasing hippocampal neurogenesis.

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The researchers conclude their study by writing:

"Whether anti-anxiety interventions can reduce risk of developing neuropsychiatric illness needs to be established with longitudinal studies."

The paper is posted online this month in the journal Current Opinion in Psychiatry.

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Prolonged stress destroys memory, new study reveals

According to a new study from researchers at The Ohio State University, long-term stress destroys memory, and the immune system plays a vital role in the cognitive decline.

Long-term stress has been known to cause chronic muscle tension, heart problems, and fertility problems in both men and women. Now, the latest study performed in mice and published in the Journal of Neuroscience suggests chronic stress causes inflammation in the brain, which ultimately leads to memory loss.

The researchers said that the study in mice could one day bring about treatment for repeated, long-term mental attack such as the ones sustained by soldiers, bullying victims, and those who have to deal with beastly bosses. [Read more Small heat shock proteins act as a model for Alzheimer’s treatment]

Lead researcher Jonathan Godbout, Associate Professor of neuroscience at Ohio State said:

"This is chronic stress. It's not just the stress of giving a talk or meeting someone new.”

The first of its kind study was aimed to build the link between short-term memory and prolonged stress. Researchers stressed out several mice by periodically putting a much more aggressive mouse into their cage. [Read more Eating sweet food forms memory of the meal – findings could encourage novel treatment for obesity]

After six days of exposure, the stressed mice could no longer recall the location of a hole to escape a maze, which they remembered easily before the stressful period began.

"The stressed mice didn't recall it. The mice that weren't stressed, they really remembered it," said Godbout.

The stressed-out rodents had changes in their brains, including inflammation brought on by their own immune system. Short-term memory loss was caused by inflammation in the brain, itself the result of the appearance of immune cells called macrophages.

Thus, the researchers pinned the brief memory loss on inflammation, and on the immune system. [Read more How many carbs should you eat if you’re trying to lose weight?]

Godbout said that the effect on memory and evidence that the inflammation in the brain is caused by the immune system are crucial new discoveries.

"It's possible we could identify targets that we can treat pharmacologically or behaviorally," he said.
John Sheridan, co-author and Associate Director of Ohio State's Institute for Behavioral Medicine Research believes it could be that there are ways to interrupt the inflammation.

The mice in the study were exposed to what psychologists call 'repeated social defeat' – in other words they were bullied by a dominant alpha mouse. This was aimed to mimic humans who experience chronic psychosocial stress. [প্রতিদিন কফি পান আপনাকে দীর্ঘদিন বেঁচে থাকতে সাহায্য করবে]

Researchers want to bring to light the secrets behind stress and mood and cognitive problems with a long-term goal of discovering ways to help people who are depressed, anxious and suffer from conditions such as post-traumatic stress disorder (PTSD).

They found that the bullied mice had problem with spatial memory and avoided social contact for up to four weeks, indicating depressive-type behavior.

The stress, it seemed, was causing the mice’s immune systems to attack their own brains, causing inflammation. [প্রতিদিন ফ্রেঞ্চ ফ্রাই খাওয়ার অভ্যাস আপনার মৃত্যু ত্বরান্বিত করতে পারে]

The researchers dosed the mice a drug known to reduce inflammation to see how they would respond. They found that neither the problem in their brain-cell nor the symptoms of depression went away. However, there were no more memory loss and inflammatory macrophages.

The finding led to the conclusion that post-stress memory problem is directly connected to inflammation, and the immune system, rather than brain damage. The impact on memory and confirmation that brain inflammation is caused by the immune system are important new discoveries, said Professor Godbout, and could open new avenues for immune-based treatments. [Read more Changes in brain occur 20 years before Alzheimer’s onset]

Sheridan concluded:

“Stress releases immune cells from the bone marrow and those cells can traffic to brain areas associated with neuronal activation in response to stress.”

“They're being called to the brain, to the center of memory.”

While this isn’t the first time researchers tried to find the link between chronic stress and memory loss, or between inflammation and depression, it gives a new, encouraging connection between all four. The doctors could be benefited by it which may enable them to prescribe more treatments for conditions that are focused on the immune system such as, depression, and anxiety.

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