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Connection, Compassion and the Genome

Posted on June 8, 2014 at 9:17 AM Comments comments (91)
Steve Cole, Phd one of the pioneer researchers in the new field of psycho-immunology, delivers the Meng Wu Lecture at CCARE Stamford University. Watch it here.

My transcript of Steve Cole's lecture: 

How we interact, how we connect has a tremendous influence on how our genes are expressed.  Traditionally we saw ethics, morality and the world of tangible, molecular biology of cells as very different worlds/domains. We are starting to see the shadow of each domain playing out in the other.
Gene expression and social factors

The genome isn’t expressing all its 20.000 genes at the same time. There is a lot of decision about which genes get expressed. The change of the activity of genes within our white blood cell is linked to
protracted, extended situations:
  • Low SES (social-economic status) 
  • Social Loss/ Anticipated bereavement
  • Post-traumatic stress
  • Cancer diagnosis
  • Social threat
  • Loneliness
  • Social instability
  • Chronic stress
  • Low social rank
  • Caregiving for seriously ill
  • Depression
  • Early life low SES
  • Poverty

The stress-response and the genome 

From a study by Irwin and Comle, Nature Reviews, Immunology, 2011
One of the major ways in which these experiences play on the genome is through the fight-flight stress response activated by the sympathetic nervous system, with the release of adrenaline (epinephrine) and noradrenaline (norepinephrine). Noradrenaline is released in the vicinity of a cell. Through its nteraction with receptors (ADRB2) on the surface of the cell the result is a pumped-up activity of genes involved in the expression of pro-inflamatory immune response genes and a stomping down of the activity of other genes (antiviral immune response genes).  

Through exposure to really overwhelming stress a second response kicks in – a defeat/withdrawal response, where your system shuts down, you are overwhelmed and your body hunkers down and just tries to survive. That response is mediated by a second hormonal pathway - the HPA (Hypothalamus - Pituitary - Adrenal). The hypothalamus tells your adrenal glands to produce more cortisol, which has a different impact on gene expression – it lowers the expression of antiviral immune response genes and lowers the expression of pro-inflammatory immune response genes.
Different experiences of the same event – either as a challenge that can be overcome or as something profoundly overwhelming is going to have different effects on my genome, it will evoke different kinds of biological response.

Studies by Cole et al. Proc Nat Acad of Sci USA, 2011 and Powell et al. Proc Nat Acad of Sci, USA, 2013
Our bodies are extremely dynamic at a cellular or molecular level. The average protein in the human body has a half-life of eighty days so that every single day we have to replace 1 – 2% of the proteins in our body and that process is open to ‘advice’ from the world outside the body, including the world that psychology creates in my mind. 

Gene expression can also catalyse the production of new cells (monocytes and dendritic cells which don’t live very long). This process is also orchestrated by changes in gene expression that are susceptible to regulation by the nervous system. In people who are confronting uncertain environments, the brain interprets those environments as threatening and activates these fight-and-fight responses. 

Norepinephrine signalling is delivered into the bone marrow in a form of a ‘piece of advice’ to the stem cell which says 'produce more myeloid cells: monocytes, granulocytes, dendritic cells'. As a consequence of that we have more of these cells going out into the body and circulating. For most of our development that made good sense but if there is nothing for those cells to respond to - because there is no physical injury and hence no bacterial infections. These cells are programmed to find trouble and do something about it. Some of the trouble they find might be the early stages of proliferation of cancer or damage to the wall of our blood vessels or minor damage in brain cells, all of which attracts these charged, primed immune cells. As these cells attempt to repair tissue damage but can inadvertently contribute to the sort of disease that nowadays are the true architects of our longevity . We no longer die of infectious disease, we now die of heart disease, cancer and neuro-degenerative diseases.


(Sloan et al. 2010 Cancer Research – done on a mouse injected with cancer cells and then confined to a small space – a stress inducing situation)
When animals have too many of these charged up monocytes in their body during the early stages of tumour-development they get many more cancer cells escaping from the initial tumour site and spreading out (metastasising). This is mediated by those immune cells, which having gone into the tumour to kill the microbes and repair damaged tissue. They liquify tissue so that the cancer cells can grow out, they help grow blood vessels into the tumour thus feeding it and suppress the rest of the immune system’s response to the growing cancer.
Psycho-social events alter our biology

We used to think of the brain and the immune system as separate it turns out that what is going on in the world has some association with what goes on in our body at a microbial level. Over millions of years our immune system has learned to listen to the chatter from the brain and if it hears indications that you are feeling substantially threatened it gets ready to deal wit tissue damage, whether tissue damage is happening or not and inadvertently it fertilisers diseases and becomes the architect of a host of problems.
-       Central nervous system: inflammation and neuro-degenerative disease
-       Vasculature: artherosclerosis
-       Lungs: URI, asthma
-       Lymphoid tissue: neoinnervation, HIV/SIV
-       Solid tumor in the breast, ovaries: metastasis
That is why so many different types of adversity (isolation, low SES, social threat, bereavement) seem to draw out disease. There are many different ways that humans have learned to feel threatened and stressed.

Attachment and isolation and how the body responds to stress

There are two different ways to run our bodies which correspond to two social genomic programs in immune cells. One operates in a world in which we are attached and safe, connected. In this the big threats that we confront are the diseases that travel from one to another (viruses). A separate modus operandi takes place in the context in which we are separated from our community or feel threatened within our community, which up-regulates these inflammatory genes which produce monocytes, geared to fight bacteria (in anticipation of tissue damage). It doesn’t help us as well because it fertilises chronic diseases.  
Hedonic versus eudaimonic happiness

What is the secret to making people feel genuinely safe? (Frederickson et al., PNAS, 2013) How should we live? What is the best way to thrive in human life? What is the nature of true happiness. Hedonic happiness: consuming happy experiences (Epicur). Eudaimonic happiness: satisfaction that derives from a deeper sense of making a contribution to a purpose or a group outside ourselves, a community, a cause, creation, discovery. It turns out that either eudaimonic or hedonic pursuits are correlated to low levels of depression, but when researchers asked the genome, eudaimonic happiness is correlated with healthy immune profiles whereas hedonic happiness is not.  

How psychotherapy changes the brain

Posted on April 22, 2013 at 7:45 AM Comments comments (93)
Here is an article published in the journal "Molecular Psychiatry" - How Psychotherapy changes the brain: the contribution of functional neuro-imaging. The author is DEJ Linden from the School of Psychology, University of Wales Bangor, Bangor, UK and 
North West Wales NHS Trust, Bangor, UK. 

Article abstract:
"This paper reviews functionalneuroimaging studies on psychotherapy effects and their methodological background,including the development of symptom provocation techniques. Studies of cognitivebehavioural therapy (CBT) effects in obsessive-compulsive disorder (OCD) were consistentin showing decreased metabolism in the right caudate nucleus. Cognitive behavioural therapy in phobia resulted in decreased activity in limbic and paralimbic areas. Interestingly, similareffects were observed after successful intervention with selective serotonin reuptakeinhibitors (SSRI) in both diseases, indicating commonalities in the biological mechanisms ofpsycho- and pharmacotherapy. These findings are discussed in the context of currentneurobiological models of anxiety disorders. Findings in depression, where both decreasesand increases in prefrontal metabolism after treatment and considerable differences betweenpharmacological and psychological interventions were reported, seem still too heterogeneousto allow for an integrative account, but point to important differences between the mechanismsthrough which these interventions attain their clinical effects."

Resources on 'dissociation'

Posted on April 22, 2013 at 6:48 AM Comments comments (94)
From Louis Cozolino “The Neuroscience of Psychotherapy” [2o1o] 

Dissociation is a result of high levels of stress associated with traumatic experiences. It occurs when the fight or flight response would be maladaptive, or when there is no response to one’s distress. It is a switch from hyper-arousal to hipo-arousal. In infants it is manifested as a gradual lack of protest [this is the reason why until recently it was believed that infants were insensitive to pain and so surgery was performed on infants without anaesthesia It is characterized by “a disconnection among thoughts, behaviours, sensation and emotions; dissociation demonstrates that the coordination and integration of these functions is an active neurobiological process.” [p. 2o-21] 

“Dissociation allows the traumatised individual to escape the trauma via a number of biological and psychological processes”. [p.269] The brain releases endogenous opioids which create a sense of wellbeing. The explicit processing of overwhelming traumatic situations is decreased [hippocampus]. “Derealization and depersonalization reactions allow the victim to avoid the reality of his or her situation, or watch it as a detached observer. These processes can create an experience of leaving the body, travelling to other worlds, or immersing oneself in other objects in the environment…” [p.27o] 

“General dissociative defences resulting in an aberrant organization of networks of memory, fear, and the social brain contribute to deficits of affect regulation, attachment and executive functioning. The malformation of these interdependent systems result in many disorders that spring from extreme early stress. Compulsive disorders related to eating or gambling, somatization disorders in which emotions are converted into physical symptoms, and borderline personality disorder all reflect complex adaptations to early trauma” [van der Kolk, 1996 in Cozolino, 2o1o, p. 27o]

The neuroscience of borderline personality disorder [p.282-283] [Also see Zero degrees of empathy by Simon Baron-Cohen]
-       An overactive amygdala, primed to react to any indication of abandonment.
-       Easily triggered fight or flight reaction [hypothalamus- pituitary –adrenal axis resulting in the release of adrenaline and cortisol]
-       Orbitofrontal cortex inadequately developed so it cannot successfully inhibit the amygdala. Self-soothing is not possible.
-       Orbitofrontal dissociation may result in disconnection between right and left hemisphere and top-down processing leading to dramatic shifts between positive and negative appraisals of relationships.
-       The absence of internalized models of affect regulation so the patient cannot draw on these to self-soothe
-       Rapid fluctuations between sympathetic and parasympathetic states
-       Chronic high levels of stress hormones [cortisol] which compromise the functioning of the hippocampus, decreasing declarative, explicit memory and the capacity to control the amygdala.
-       Lower levels of serotonin resulting in greater risk of depression and irritability.-       Self-harming results in endorphin release and sense of calm 


“Dissociation in reaction to trauma represents a breakdown of neural integration and plasticity. In therapy, we use moderate levels of arousal to access cortical mechanisms of plasticity in controlled ways with specific goals. The safe emergency of therapy provides both the psychological support and the biological stimulation necessary for rebuilding the brain. Much of neural integration and reorganization takes place in the association areas of the frontal, temporal and parietal lobes, serving to coordinate, regulate and direct multiple circuits of memory and emotion… narratives embedded within an emotionally meaningful relationship are capable of resculpting neural networks throughout life. Through the use of autobiographical memory, we can create narratives that bridge processing from various neural networks into a cohesive story of the self” [Cozolino, 2o1o, p. 343]

From Daniel Siegel’s “The Mindful Threapist: A clinician’s Guide to Mindsight and Neural Integration”“Dissociation involves various elements along a spectrum including a sense of being unreal, feeling numb or disconnected from one’s body, feeling depersonalization or a kind of distance from being grounded in oneself, and outright amnesia for events in one’s ongoing life.” [Siegel, 2o11, loc. 1377] 

These experiences recur mainly under stress and are associated with unresolved trauma and loss and a disorganized attachment style. Dissociation is a protective state in a situation in which there is no escape from terror  or “fear without solution” [Main, Hesse, Yost-Abrams and Rifkin, 2oo3 in Siegel 2o11]
The opposite of a dissociated or disorganized state is an integrated state. There are different levels of integration, just as there are different levels of dissociation.
Vertical integration – mind/body is facilitated by interoceptive awareness [posterior insula] Being aware of what is happening inside one’s body and using this information to make sense of our reality
Bilateral integration – left hemisphere/right hemisphere [logic, verbal/metaphoric, implicit, non-verbal] 
Being able to use logic but also metaphor. [See Iain McGilchrist- the Master and his Emissary]
Memory integration – implicit memory/explicit memory [amygdala/hippocampus]
Narrative integration- the existence of a coherent autobiographical story

Additional resources:  “The History of Dissociation and Trauma in the UK and its impact on treatment by Remy Aquarone and William Hughes” available online at:
Stephen Porges - "The polyvagal theory". Porges talks about incapacitation [fainting, passing out] as a distinctive coping mechanism, neurologically very different from sympathetic arousal [fight or flight response]

Affective neuroscience: Pro-social behaviour

Posted on January 11, 2013 at 5:07 PM Comments comments (106)
Stephen W. Porges is one of the world's leading experts in the autonomic nervous system, and author of a book titled "Polyvagal Theory - Neurophysiological foundations of emotions, attachment, communication and self-regulation". The book is basically a collection of articles published during a career spanning 40 years. 

Telluride conference on compassion 
I first learned about his work a couple of months ago when I watched the YouTube posted footage of the Compassion science conference organised by CCARE Stanford in Telluride, Colorado, in July 2012. Watching him deliver his presentation, Mr. Porges impressed me as an anxious, vulnerable man who self-admitted to feeling a bit lost as he couldn't see the faces of his audience and said he found it difficult without being able to gauge the feedback from facial expressions. The organisars duly turned on the lights and offered him a glass of water and he saluted this act of "pro-social behaviour". 

Porges' theory combines observations on comparative anatomy about the development of the nervous system from fish to reptiles to mammals, with the study of the nervous system of newborns, insights from psychiatric conditions in which pro-social behaviour is impaired (autism, depression). Porges states that his scope is both scientific and humanistic - in that he wants to promote better, more humane care practices amongst clinicians, that honour the healing power of human relationships. 

Autonomic nervous system
Porges focuses on a part of the Autonomic Nervous System - the para-sympathetic nervous system (PNS), which traditionally was believed has an antagonistic relationship with the sympathetic system (SNS). The PNS consists of cranial nerves that have efferent (taking information to the body and internal organs) and afferent branches (that bring information from the body and the internal organs). 

The vagus nerve
The thenth cranial nerve (X), also called the vagus nerve is of particular interest. This nerve has two pathways - an unmyelinated one, which originates in the dorsal motor nucleux (DMNX) and a myelinated one, which originates in the nucleus ambiguus (NA). Myelinated nerves transmit information much faster. The myelinated vagus is a mammal "invention". Reptiles do not have it. What reptiles do have, is an unmyelinated vagus. The role of this nerve is to massively slow the heart's pacemaker - an important part of death-feigning. For mammals it is extremely dangerous to resort to death-feigning as a strategy to escape danger. A massive slow-down in breathing and heart-beat can cause cause serious damage to the mammalian oxygen-hungry brain and body. So mammals also have a myelinated vagus nerve, which makes sure that the unmyelinated nerve does not stop the heart.

Myelinated vagus, a mammal invention
What is interesting about the vagus nerve is that it's branches do not only innervate the heart, but also the facial muscles, the larynx, the pharynx and the inner ear muscles. This means in effect that engaging in pro-social behaviour - communicating with our face and voice, listening also has the effect of maintaining our heart beat within the normal range and preventing us from going into a state of mobilization (sympathetic activation characterized by flight, fight or freeze behaviour) or immobilization - death feigning). Basically it's like a neural brake that stops us  from "literally bouncing off the walls" (Porges, p.31) 

Hierarchy of behavioural responses
Vagal tone is highest when we are in a non-threatening situation. If we detect danger in the environment, then vagal tone withdraws and the body is now under the influence of the sympathetic nervous system, which gears it through hormones such as norepinephrine (noradrenaline) and cortizol to send all available energy into the muscles in order to fight or freeze, or run away. A state of mobilization is incompatible with pro-social behaviour. Traumatized clients which are easily triggered to feel angry or scared may not be available to be contacted through conversation and reasoning. 

Misreading the environment
What is interesting is that not only does the environment affect our internal state, our internal state also "colours" the way we interpret our environment. Traumatized individuals who are constantly in a state of agitation, are also more likely to "misread" cues from the environment and interpret them as dangerous. This is why working with clients diagnosed with borderline personality disorder is so difficult. No matter how benign and benevolent the therapist believes she is, the client easily mis-reads and mis-interprets her actions. The transactional analysis cathexis school calls this phenomenon "re-framing" (Schiff). Reframing, far from being a conscious process seems more likely that is "wired" into bodily responses which were geared to deal with harmful, dangerous environments. 

If the situation is interpreted to be imminently life-threatening and the emotional response triggered is one of terror, then the unmyelinated vagus takes over and slows the heart right down. The result is immobilization (fainting, dissociative state). In transactional analysis language, client becoming immobilized is an indication that they are cathecting a severely traumatic Child ego-state. 

Porges basically says that in any given situation we will employ the evolutionarily newest neural systems - those involved in pro-social behaviours. If this strategy fails then the sympathetic system will activate to promote flight, fight or freezing and if that fails as well, we will go into immobilization (fainting, dissociation). 

Other important researchers
If I had a criticism of Porges is that like any researcher absorbed by his area of focus he tends to downplay the importance of other neural areas involved in the process. He barely mentions the work of Damasio, LeDeux, Richardson and Sapolsky. Damasio talks about the importance of the medial-prefrontal cortex in self-control. LeDeux talks about the way in which "news" of possible danger hit the amygdala before the prefrontal cortex through a "fast and dirty way", which means that we react before we've had time to assess what it is that we are reacting to. Richardson focuses amongst other things on the insula, involved in representing bodily states and Sapolsky is an expert in stress and the sympathetic activation and its effects on the hippocampus. 

Implications for practice
I think Porges' theory supports humanistic practices such as person centred and body-based psychotherapy as facial expressiveness, a positive warm presence and caring attitude which are valued in these types of therapies are also proven to promote states of calm and healing. I think that this theory challenges traditional psychoanalytic approaches such as neutral stance and non-disclosure which I think can trigger mobilization in already traumatized individuals. It also challenges health professionals in general - doctors and nurses, who traditionally are more concerned with performing the tasks and operations needed to maintain and promote bodily function and are less concerned with how they relate to their patients and the potentially harmful impact of their distant stance.  

PTSD and archeology. All in the mind BBC Radio 4

Posted on December 12, 2012 at 6:40 AM Comments comments (97)
Preventing PTSD; Archaeology and mental health; Organophospates.

Programme synopsis: 

" "Bob", the Armed Forces, the Police and PTSDA former member of the armed forces and a policeman, "Bob", suffered Post Traumatic Stress Disorder or PTSD following the shocking death of a young woman that he was spending the evening with. He tells Claudia Hammond that he's only recently received the help he needed to get his life back on track and admits that he believes many people in the emergency services have, like him, untreated PTSD.The statistics confirm "Bob's" suspicions, which is why research at Kings College, London, and Oxford University is of such interest. Dr Jennifer Wild and her doctoral student, Rachel White, have discovered that by training people to concentrate on HOW the event is unfolding rather than WHY, significantly fewer PTSD-type symptoms are reported.

Researchers exposed volunteers to traumatic films with visuals of accidents and deaths, but whereas those in the WHY group were encouraged to focus on the abstract, on why such terrible things happen and what it would mean for the people involved and their families, the HOW group was prompted to focus on the specific and objective details of the event without straying into its greater meaning.The results showed that the WHY group suffered from more intrusive memories, flashbacks and hyper-arousal than the HOW group, suggesting that if emergency workers could be trained to change their thinking, then psychological trauma could be reduced.Past In MindA chance meeting on a train between archaeologist Ian Bapty and Herefordshire MIND worker, Jenny McMillan, led to an unusual collaboration: an archaeological dig to excavate a lost village. 

The Past In Mind project brought together archaeologists, historians and people recovering from mental health problems on the Lower Brockhampton Estate in Herefordshire to search for the lost medieval settlement of Studmarsh. Volunteers made an audio diary for All in the Mind from the dig. Organophosphates Government advisers on the Committee on Toxicity have been sent a new review on organophosphates which suggests that low level exposure causes damage to the brain and nervous system.

Dr Sarah Mackenzie Ross, a neuropsychologist from University College London is one of the authors of the meta-analysis - a systematic review of the best available evidence - and she tells Claudia Hammond that the evidence suggests that people who have been exposed to low levels of organophosphates have impaired cognitive function.Organophospate pesticides are the most widely used insecticides in the world in agriculture and horticulture. They're also used in industry as lubricants, plasticizers and flame-retardants and pest-control teams use them too. 

But it's been known for some time, despite their importance in food production and disease prevention, that in high doses, they damage the brain and the nervous system. What's more controversial is whether there is a risk from low-level exposure to organophosphates, so this latest publication will be of interest to the Committee on Toxicity which is currently reviewing this subject." 

Stanford prison experiment

Posted on December 12, 2012 at 6:30 AM Comments comments (98)
"The Stanford prison experiment was a study of the psychological effects of becoming a prisoner or prison guard. The experiment was conducted from August 14 to 20, 1971 by a team of researchers led by Psychology professor Philip Zimbardo (Also the host of the documentary series Discovering Psychology) at Stanford University. It was funded by a grant from the U.S. Office of Naval Research and was of interest to both the US Navy and Marine Corps in order to determine the causes of conflict between military guards and prisoners.

Twenty-four students were selected out of 75 to play the prisoners and live in a mock prison in the basement of the Stanford psychology building. Roles were assigned randomly. The participants adapted to their roles well beyond what even Zimbardo himself expected, leading the "Officers" to display authoritarian measures and ultimately to subject some of the prisoners to torture. In turn, many of the prisoners developed passive attitudes and accepted physical abuse, and, at the request of the guards, readily inflicted punishment on other prisoners who attempted to stop it. The experiment even affected Zimbardo himself, who, in his capacity as "Prison Superintendent," lost sight of his role as psychologist and permitted the abuse to continue as though it were a real prison. Five of the prisoners were upset enough by the process to quit the experiment early, and the entire experiment was abruptly stopped after only six days. The experimental process and the results remain controversial.

The results of the experiment are said to support situational attribution of behavior rather than dispositional attribution. In other words, it seemed the situation caused the participants' behavior, rather than anything inherent in their individual personalities. In this way, it is compatible with the results of the also-famous Milgram experiment, in which ordinary people fulfilled orders to administer what appeared to be agonizing and dangerous electric shocks to a confederate of the experimenter."

Learning begins before birth

Posted on November 29, 2012 at 8:42 AM Comments comments (0)

About the speaker 
"To what extent the conditions we encounter before birth influence our individual characteristics? It‘s the question at the center of fetal origins, a relatively new field of research that measures how the effects of influences outside the womb during pregnancy can shape the physical, mental and even emotional well-being of the developing baby for the rest of its life.

Science writer Annie Murphy Paul calls it a gray zone between nature and nurture in her book Origins, a history and study of this emerging field structured around a personal narrative. Paul was pregnant with her second child at the time. What she finds suggests a far more dynamic nature between mother and fetus than typically acknowledged, and opens up the possibility that the time before birth is as crucial to human development as early childhood."

In the nine months before birth a baby learns answers to critical questions about the environment it will be born into: Am I born into a world of plenty or hunger? Am I born into safety or danger? 

Pre-natal starvation and stress influence the ways our bodies and brains develop after birth. 

For example, the so-called Dutch Hunger Winter babies, babies whose mothers had starved during pregnancy under the NAZI siege, decades later had more obesity, more diabetes and more heart conditions compared to individuals who gestated under normal conditions. 

Their pre-natal experiences had changed their biological profile. The explanation is that the fetuses tailor their physiology and metabolism in anticipation of the kind of world they will encounter beyond the womb. The basis of this prediction is what the mother eats, which becomes an unspoken narrative, a story about abundance or starvation. A child with very little energy requirements will survive a time of scarcity better, so the fetus adapts to have a slower metabolic profile. The problem arises when the mother's unspoken narrative is unreliable. Bodies that are built to survive on very little calories were born into a post-war world of plenty and were ill equipped to deal with surplus which requires a higher metabolic rate. Hence the high incidents of obesity and type II diabetes. 

Another example. Babies of a group of mothers who were present at the 9/11 disaster and developed PTSD as a result, were themselves predisposed to this condition. Researchers found a biological marker linked to PTSD. In a very dangerous environment, what looks like pathology to us - hyper-vigilance, a quick-trigger response to danger, are adaptive. In a sense the mothers stress profile is indirectly informing and warning their unborn babies that it's a dangerous world out there and the fetus "prepares" himself to surviving in this world. 

Childhood adversity affects brain function. Guardian science article

Posted on November 20, 2012 at 5:53 PM Comments comments (95)
Childhood adversity affects adult brain and body functions, researchers find. Poverty can impair working memory while physical abuse can raise risk of cardiovascular disease, scientists claim.

By Alok Jha, science correspondent (The Guardian, 16th of October, 2012)

Growing up in a low socioeconomic background can impair working memory as an adult and affect the size of different parts of the brain, researchers say. Photograph: Jeff J Mitchell/Getty ImagesAdversity in early childhood – in the form of anything from poverty to physical abuse – has measurable changes in the function of the brain and body well into adulthood, according to researchers.

Growing up in worse socioeconomic circumstances can impair working memory as an adult and affect the size of different parts of the brain, while abuse can lead to a higher risk of developing cardiovascular disease in later life, they report.

In a series of presentations at the annual meeting of the Society of Neuroscience in New Orleans on Tuesday, scientists reported on work studying critical periods of development for the brain. 

Eric Pakulak, at the University of Oregon, found that people who grew up in homes with a lower socioeconomic status had greater deficits in working memory, compared with those from wealthier homes, even when he controlled for the participants' education.Working memory, Pakulak said, was broadly associated with general intelligence. "As a four- or five-year-old, if you have very good attention and regulations skills, it's a foundational skill that would spill over into other areas of cognition – if you're trying to learn your letters, or to read, or learning numbers or math or a musical instrument. When you're learning a musical instrument, you're really training attention."He asked 72 adults to complete a test of working memory, where they had to remember the final words from a series of sentences. 

On average, adults from lower socioeconomic backgrounds could remember two words whereas those from more wealthy backgrounds, on average, got up to four words.Suzanne Houston, of the University of Southern California, showed that the size of different parts of the brain could be affected by growing up in different homes. "We found higher parent education, smaller amygdala. The higher the income, the larger the hippocampus."The overall size of brain regions was not of primary significance, she said, but the fact they were measurably different would allow scientists to tease out what sorts of differing environmental factors might be affecting the brain development of children from different backgrounds.Understanding environment can also help scientists to modify it. 

Pakulak said his work had informed the development of teaching courses that could, by working with parents and pre-school children from lower socioeconomic status backgrounds, improve aspects of parents' behaviour and reduce their stress, as well as improving children's behaviour and cognition within weeks."Most powerfully, we've shown that, after eight weeks, children in our intervention training group show the same [result for] brain function for selective attention that their higher [socioeconomic backgrounds] peers show," Pakulak said.

Layla Banihashemi, of the University of Pittsburgh, focused on the enduring effects of physical abuse in childhood. She found that adults who suffered physical abuse as children had greater increases in blood pressure when they engaged in stressful tasks as adults. Overall, she said, this would put them at greater risk of developing cardiovascular disease.

She asked 155 healthy adults, who were 40 years old on average, to complete a childhood trauma questionnaire, a standard way of assessing the level of physical abuse someone may have suffered as a child. "As physical abuse scores increased from none to moderate to severe levels, we saw significant increases in the change in blood pressure in response to stress," said Banihashemi.The mean arterial blood pressure in people who had suffered no abuse during childhood changed by 2.73mmHg, from a baseline of around 90mmHg, when they were stressed in Banihashemi's experiment. In the low abuse group, the average change was 4.71mmHg, and moderate or severe abuse in childhood elicited an average change of 5.45 mmHg. "People that have these heightened blood pressure responses, in magnitude and duration, are more at risk at developing cardiovascular disease," she said.

Banihashemi added that most of the participants in her study were not in the severely abused category. "They are primarily within the minimal range – I think this is unique because it indicates that even minimal to moderate levels of abuse can influence stress responses of the brain and body."Andrea Danese, a clinical lecturer in child and adolescent psychiatry at King's College London's Institute of Psychiatry, said the series of studies addressed important questions in the understanding of how childhood experiences shape adult lives.

Pakulak's work, he said, was particularly interesting because it showed how it was possible to remediate the consequences of a lack of opportunity early in life. "These changes might support upward social mobility and improve family environment across generations."He added that replication of developmental studies would be crucial in working out which effects are real and which are not. "A key limitation is that human studies linking early experiences to later brain, psychological, or health outcomes are observational in nature," he said. "For ethical and practical reasons, researchers can seldom actively manipulate children's experiences and more often have to passively observe differences in experiences and relate them to certain outcomes.

"However, because different experiences or vulnerabilities – poverty, insufficient stimulation, maltreatment, parental mental illness, low IQ – often occur together in the same children, it is challenging to confidently point to the effects of one specific experience without its active manipulation."

Previous meta-analyses have shown that being sexually or emotionally abused as a child can affect the development of a part of the brain that controls memory and the regulation of emotions. In addition, people with a history of abuse or maltreatment during childhood are twice as likely to have recurrent episodes of depression in adulthood. These individuals are also less likely to respond well to psychological or drug-based treatments.