Tuesday, May 5, 2009

Poverty and the Brain

• The greater proportion of life that a child has spent in poverty, the greater the neurological effects (See chart).

Measuring Stress

• Turner and Avison measured social stress in all socioeconomic brackets using five categories: recent life events, chronic stress, lifetime major and potentially traumatic events, discrimination stress, and symptoms of depression. They found that, “With the exception of recent life events, those in the lowest third of the socioeconomic status distribution reported higher stress levels in every category and, for essentially every category, the socioeconomic status-stress relationship is monotonic: The lower the socioeconomic status the higher the stress” (Turner and Avison, 2003).

Biological measures of stress

• Allostatic load: “a biological marker of cumulative wear and tear on the body that is caused by the mobilization of physiological systems in response to chronic environmental demands” (Evans et. al. April 2009).
• Relevant Hormones: Catecholamines such as norepinephrine, dopamine and epinephrine (adrenaline), and Glucocorticoids (mainly Cortisol)
o Control physiological responses to stress in the sympathetic nervous system like blood pressure and heart rate
o Fight-or-flight reactions
o Energy regulation: They replace energy reserves after high-stress events (restore homeostasis after high stress).
o Regulate cardiovascular system, metabolism, blood sugar, immunological responses, homeostatic functions
o Cortisol and epinephrine work together to create memories of stressful events (flashbulb memories).
• These neuroendocrine responses are important for adaptation to stressful situations, managing acute threats and maintaining homeostasis (internal stability) and allostasis.
• When these stress responses are engaged on a regular basis, they result in an allostatic load that causes the body and brain to deteriorate
• Chronic exposure to high levels of cortisol can inhibit development of the hippocampus and even stop the process of neurogenesis

Physical Factors
• Inadequate nutrition (including iron-deficiency anemia which inflicts 25% of low SES children in America)
• Substance abuse in pre- and post-natal development
• Trauma and abuse
• Exposure to environmental neurotoxins, including lead. For every 10 micrograms per deciliter increase of lead in the blood there is an estimated 2.6 decrease in IQ (Schwartz, 1994).

Psychological Factors

• Many low-SES families live in neighborhoods with high crime rates
• Job instability/issues
• The difficulties of providing for basic needs cause stress and tension within families and deeply affect children.
• Maternal depression (social interaction)
• Quality of daily care
• Less exposure to cognitive stimulation (books, toys, museums, zoos, etc.)
• Average total hours of one-on-one picture book reading for children entering Kindergarten: Low-SES children 25 hours, Middle-SES children 1000-1700 (Adams 1990).

What systems are affected by stress?

• The left Perisylvian/language system is responsible for many aspects of cognition and communication, including semantic, syntactic and phonological aspects of language, and is concentrated in the temporal and frontal areas of the left hemisphere of the brain.
• The Medial/Temporal Memory system makes it possible to retain a memory or representation after a single exposure to a stimulus (as opposed to representations that are strengthened gradually through repeated exposures). This ability relies on the hippocampus and parts of the medial temporal lobe.
• The Prefrontal/Executive system is dependent on the pre-frontal cortex and “enables flexible responding in situations where the appropriate response may not be the most routine or attractive one, or where it requires maintenance or updating of information concerning recent events” (Farah et. al. 2005).

Specific Correlations: Home Observation and Measurement of Environment (HOME) Tests, Children at ages 4 and then 8.

o Performance on Left Perisylvian/Language abilities was correlated with average cognitive stimulation (variety of toys, availability of books, language stimulation, parental speech designed to engage child, academic stimulation, behavior modeling, etc.)
o Performance on Medial temporal/Memory ability was predicted by social/emotional nurturance (warmth, affection and engagement, acceptance, emotional and verbal responsivity, encouragement of maturity, emotional climate, paternal involvement).


Contributes to the discourse about childhood poverty, framing the issue as one of bioethics rather than economic opportunity

Solutions and policy implications

How the Amygdala Responds to Shape

Space-how does it affect thought? It should seem obvious that a space can induce certain emotions—high ceilings tend to give us a feeling of openness and light, while low ceilings may feel dark and confining. How does shape affect thought?

The purpose of the experiment was to study how humans react to the presence of smooth, curved contours versus their reaction to sharp-angled contours. The hypothesis was that the reaction to objects or patterns with sharp contours would be more negative than the reaction to objects or patterns with curved contours.

There were sixteen participants, eight males and eight females; all were healthy with normal vision. None were aware of the purpose of the study. In addition to hypothesizing that the participants would like the sharply contoured images less than the smoothly contoured images, the researchers also hypothesized that the amygdala would be activated when making this snap decision. They used an fMRI to test their hypothesis.

140 pairs of real objects (Part A in Figure 1), like a chair, a plant, or a shirt, and 140 pairs of novel, meaningless designs (Part B in Figure 1) were collected. The meaningless designs were created by the researchers and were simply patterns. All of the pairs were presented on a computer screen in grayscale. One item in each pair was with curved contours, and one item had sharp-angled contours. There were also 80 control images that had an approximately equal amount of sharp angles and smooth contours. (Part C in Figure 1)

Each image was presented for 85 ms, followed by 1915 ms during which the participant had to make a qualitative, instinctual judgment about the image—that is, whether or not they liked or disliked it. (Part D in Figure 1) Image and video hosting by TinyPic

The results of the study showed that the overall, the participants liked the curved images more than the control images, and they liked the control images more than the sharp-angled images. This showed that the participants liked the curved images more than the sharp-angled images.

The fMRI results showed that there was considerably more activity in the amygdala when the participant was observing an image with sharp contours.
Image and video hosting by TinyPic

This was consistent for both the real objects and the patterns. The researchers think this may be because the sharp angled objects present more of a threat.Image and video hosting by TinyPic

A second experiment was done to rule out the possibility of the results merely reflecting whether the participants liked or disliked the images. The researchers wanted to see if the sharp-contoured images were actually more threatening. To do this, a similar experiment was performed, in which the participants had to respond by saying whether the images were threatening or non-threatening, as opposed to whether they like or dislike the image. In this study, the participants called the sharp-angled objects threatening much more than the curved objects.

The amygdala is the part of the brain that is activated when there is danger. It makes sense that it would activate in response to a perceived threat. LeDoux discusses an experiment in which a rat is subjected to a warning signal, and then to a mild electrical shock. The rat’s response to danger is to freeze. The next time around, the rat will remember that the electrical shock follows the warning signal, and will freeze when it hears the sound. This is called the Pavlovian Response. However, damage to the amygdala deletes this process; the rat will no longer have this awareness. The amygdala is responsible for controlling this type of reactive behavior. In the same way, the amygdala is activated when a human sees a sharply contoured image.

Selective Mutism Description and Biological Etiology

Selective Mutism, once thought to be a voluntary oppositional behavior disorder, is a childhood anxiety disorder characterized by an inability to speak in some social settings, such as at school or play dates, while speaking comfortably in other situations, most often only at home with immediate family members. Other diagnostic criteria are co-conditions or results of mutism such as, interference with academic achievement, duration of mutism for more than a month, lack of a better diagnosis and a comfortable knowledge of the spoken language required (to ensure that mutism is not the result of lack of knowledge).

SM is often recognized after a child begins formal schooling, despite having spent the previous years engaging in "normal" social interaction and conversation with family. It is a relatively rare disorder, thought to affect 7 children in 1,000, but parents and teachers often write symptoms off as shyness and allow them to pass under the radar, which results in an older average age of diagnosis, as well as many undiagnosed cases. Because of its rarity there is still debate and misunderstanding about its causes and classification, but the most recent studies have lead to the now accepted conceptualization of SM as an involuntary, anxiety-related condition, most related to social phobia.
The mutism itself is a fear response to a
Although there is not enough research to adequately define the causes of SM, the available research suggests that a combination of any of the following biological and environmental factors can increase risk:

1. Innate Behavioral Inhibition
-This is a temperament identified in the majority of SM children
2. Family History of Anxiety
- Kumpulainen (2002) discovered high rates of anxiety disorders in family members of people with SM
3. Expressive Language Difficulty
- Stuttering, Echolalia, Hyperlexia
- Embarrassment related anxiety
4. Bilingual
- SM is more prevalent among children of immigrant backgrounds
- There is an expected "silent period," this can contribute to undiagnosed SM
5. Weak Social Networks
- Inconsistent or unreliable parenting
- Marital discord
- SM children may live outside of their school/community neighborhood

Dr. Shipon Blum stresses that regardless of which factors contribute to mutism, the neurobiological fear response that typically causes SM children to avert their gaze, "freeze," becoming visibly stiff and uncomfortable is consistent throughout affected children. The neurological system develops a perception that expected speech in certain social situations is a threat, this neurological perception leads to a pattern of mutism and defensive avoidance. The primary brain part associated with anxiety disorders is the amygdala, which triggers the bodily fear reaction and consequently signals the hypothalamus to activate the sympathetic nervous system in response. People with anxiety disorders have overreactive amygdalae, considered to be caused by extreme temperamental inhibition which creates a lower threshold of excitability in the amygdala, which results in an exaggerated fear response to stimuli that may not actually be dangerous.

Kagan et al., first hypothesized this lower amygdala threshold in their study on the physiology and psychology of behavioral inhibition. Their study assessed the inhibited/uninhibited responses of 21 and 31 month infants to unfamiliar people and situations. Behavioral inhibition was measured by a latency to interact with the stimuli, immediate retreat from the stimuli, reluctance to move too far away from their mother and decreased playfulness and vocal responses. The study identified a positive correlation between behavioral inhibition and physiological manifestations of the sympathetic nervous system in response to the unfamiliar stimuli at ages 21mo and 5.5 years. The exaggerated physiological responses of the behaviorally inhibited children lead Kagan to hypothesize the possibility of a lower threshold of responsibility in the limbic and hypothalamus systems.

Schwartz reopened the Kagan study ten years later for further investigations into whether innate behavior inhibition is marked by a difference in the brain. Subsequent tests around age 13 in this longitudinal study revealed consistent preservation of temperament into adolescence, and even psychopathological developments of inhibition such as generalized anxiety disorder in 1/3 of the inhibited children. Another 10 or so years later, Schwartz studied adult manifestations of behavioral inhibition. They took fMRI while the subjects viewed pictures of faces both familiarized and novel. The amygdalae in inhibited subjects showed significant reactivity to the novel faces in the series of photos, showing that some temperamental brain differences do exist and that they are consistent from early childhood to adulthood. This image data supported Kagan's original hypothesis that behavioral inhibition is connected with overreactivity in the limbic system. Temperamentally inhibited people may be born with hyperreactive amygdalae, which could increase risk of developing a social anxiety disorder.

A 2005 study on amygdalar volume in children demonstrated a consistent smaller left amygdala in subjects with social anxiety disorders when compared to a control sample of children without mental illness. Then a small sample of children with anxiety were put on an SSRI or treated with talk therapy for eight weeks. Both treatments resulted in amygdalar volume increases in every subject. This indicates that treatments for childhood anxiety disorders are actually effective.

Since SM is now widely accepted as a social anxiety disorder, treatments common for anxiety such as desensitization, reinforcement, reward measures and SSRI pharmacotherapy have been successful in SM treatment. Many SM children have been able to talk freely and participate in the mainstream tracks at their schools as a result of this treatment.

It is a common myth that SM children will "grow out of it." Case studies have shown that although children may learn to cope socially if they do not receive treatment, these children still display other symptoms of social anxiety. Current understandings of the condition encourage early diagnosis and treatment to prevent later serious mental disorders, especially since pediatric anxiety disorders are strong risk factors in the development of serious adult mental disorders. Many of the biological and environmental risk factors that contribute to the development of childhood social anxiety have been scientifically uncovered and are visible in my own family. Dr. Graham Emslie claims that the risks attributed to childhood anxiety can extend to underachievement, depression disorders and later substance abuse. Without treatment the anxiety avoidance cycle may be perpetuated and children with anxiety disorders can miss significant milestones and opportunities for growth. He asserts that since childhood anxiety disorders are now visible and can be treated, they should under no circumstances be left to develop into something more serious.

Saturday, May 2, 2009

Living on Earth: This Is Your Brain on Poverty