Understanding the Impact of Stress on Brain Development and Learning

Merriam-Webster define stress as:

A physical, chemical or emotional factor that causes bodily or mental tension

Acute stress is general short-term with a clearly defined beginning and end

Chronic stress is long-term and prolonged stress with no clear ending

Both acute and chronic stress trigger the physiological stress response

Triggering of the sympathetic nervous system which prepares the body to deal with perceived threat by: ◦ Increase of heart rate and blood pressure

◦ Increase of cortisol – “stress” hormone which has anti-inflammatory and immunosuppressive properties

◦ Decline of parasympathetic activity which regulates “automatic” bodily functions and maintains homestasis

◦ Shorter form of the serotonin transporter is associated with vulnerability to increased response to stress by developing depressive illness and alcoholism

◦ An allele of the monoamine oxidase A gene result in more vulnerability to abuse in childhood, increased risk of becoming an abuser & show antisocial behaviors.

Early abuse can result in life long emotional reactivity and stress hormone reactivity –both associated with cognitive decline and shorter lifespan in animal studies

Stress reduction in infants can be influenced by maternal bonding through a variety of factors◦ Physical proximity

◦ Modeling

Early patterns “hard-wire” the stress response –critical period during 1st nine months

Males most typically mirror the fight or flight response

Females engage fight or flight AND befriend

There is an inverted relationship between learning and levels of cortisol

During acute stress, higher levels of cortisol result in: ◦ Enhanced immunity

◦ Enhanced memory

During chronic or prolonged stress, the increased levels of cortisol result in:

◦ lower immune response

◦ Impaired cognitive functioning

The Hippocampus is the brain structure primarily responsible for learning and memory

The Hippocampus is highly sensitive and malleable

Cortisol decreases and retracts the dendritic growth in the hippocampal area

Within the Hippocampus, is the dentate gyrus, a structure which seems to play a role in the memory of sequences of events

It has high plasticity and is constantly producing new neurons, even throughout adult life.

Certain types of stress suppress neurogenesis and cell survival in the dentate gyrus

Cortisol inhibits long-term potentiation – cell sensitivity in communication

Adolescent brain is more receptive to long-term potentiation without interference

Repeated or chronic stress causes dendritic shortening in the medial prefrontal cortex

The results in impairment in attention set shifting

Both acute and chronic stress produce dendritic growth in neurons in the amygdala.

The results of include: ◦ Increases anxiety

◦ Increased aggression

In animal research, chronic stress causes atrophy of neurons in the hippocampus and prefrontal cortex

and

Hypertrophy of neurons in the amygdala

Results: ◦ Decreased learning and memory

◦ Increased anxiety and aggression

The results from animal studies are mirrored in humans through a loss of hippocampal volume and an increase in amygdala volume in MRI studies

PET scans also demonstrate altered patterns of activity in the related brain areas during stress

Learn stress management – variety of techniques

Problem-focused –changing the stressor

Emotion focused –changes our response to the stressor

Physical

Cognitive

Emotional

Behavioral

Physical Techniques:

Exercise Meditation

Relaxation

Cognitive Techniques:

Social Comparisons Re-Evaluation

Distraction

Emotional Techniques:

Social Support Release

Laughter

Behavioral Techniques:

Helping Others

Optimism is associated with lower cortisol production and higher heart rate variability (showing higher parasympathetic activity)

Optimistic people are, on average, healthier and live longer than pessimistic people

Optimistic people have higher levels of life satisfaction

Poor self-esteem has debilitating effects: ◦ Increased levels of cortisol

◦ Inability to regulate cortisol levels under stress

◦ 12-13% loss of hippocampal volume

Improve sleep quality and quantity

Have a good social support system

Maintain a positive outlook on life

Maintain a healthy diet

Avoid smoking

Regularly exercise – moderate activity

Build positive self-esteem

Learn successful stress management

McEwen, B.S. Protective and damaging effects of stress mediators: central role of the brain. New England Journal of Medicine. 1998, 338: 171-179

Q & ARobin Donaldson,

rdonaldson@nationalsafeplace.org