Posts Tagged ‘fear’


Genes that confer risk for illness are ideal targets for prevention and treatment.  So, also, are genes associated with natural or treatment-based RECOVERY from illness.  In a search for “recovery genes”, association studies in women who have recovered from eating disorders (ED) vs. those who are still struggling to recover reveals that the C-allele of rs17536211 is associated with recovery.

From Bloss et al.:  “Given the substantial genetic component in the etiology of EDs in general, it follows that there may be genetic variants that contribute to the likelihood of recovery.”

“These were women who were over age 25 years, carried a lifetime diagnosis of either AN, BN, or ED-NOS (ie, subthreshold AN or BN), and for whom data were available regarding the presence (n=361 endorsed ongoing ED symptoms in the past year and considered ‘ill’) or absence (n=115 no ED symptoms in the past year and considered ‘recovered’) of ED symptoms.”

“rs17536211, an intronic SNP in GABRG1 on chromosome 4, showed the strongest statistical evidence of association with a GC-corrected p-value of 4.63 × 10−6, which corresponds to an FDR of 0.021 (Figure 1). The odds ratio (OR) observed for this SNP is 0.46, suggesting that possession of copies of the minor allele [C] is protective from long-term chronic illness (ie, it is associated with recovery).”

How might this SNP confer a protective effect?  The authors review data on the role of GABRG1 subunits in the un-learning of conditioned fear responses [“GABRG1 subunits are found in the lateral inputs, a region that arises from the intercalated cells masses, and is thought to be responsible for mediating inhibition of amygdala output during extinction of conditioned fear (Likhtik et al, 2008)”] and suggest that individuals with the protective C-alleles may be slightly more able to uncouple eating from a very real and debilitating fear response.

*photo credit

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Hey genome, why U make me stink at networking?

If only there was an allele that LESSENED the apprehensive and uncomfortable feelings I get when meeting new people.

As such negative feelings are the work of my amygdala, I’m wishing for some sort of LOSS-OF-FUNCTION allele that REDUCES the activity of neural circuits involved in the emotional processing of fear … but leaves other neural circuits untouched.

I just want something that takes the edge off new social experiences … yunno?

How about rs33977775 ? It contains a derived (as opposed to ancestral) T-allele that causes a Y135F change that disrupts the binding sites of the NPBWR1 receptor to its neuropeptide ligands (ie. LOSS-OF-FUNCTION).  Amazingly, this receptor has a restricted pattern of gene expression only among limbic circuits involved in emotion and reward processing (ie. EXPRESSED IN EMOTION PROCESSING CIRCUITS ONLY).

In their report, a team of authors measured the reactions of 126 university students to various social stimuli and report that individuals who carry one of these loss-of-function T-alleles (about 30% of the population) show a more positive response to social interactions.

“… the AT group perceived facial expressions more pleasantly than did the AA group, regardless of the category of facial expression. Statistical analysis … also showed that the AT group tended to feel less submissive to an angry face than did the AA group.”

So it seems that rs33977775 may dial down the amygdala response to social stimuli … just enough to ace the job interview, but not so much that you inappropriately hug your new boss. Nice!

Unfortunately, this SNP is not covered by 23andMe v3 and there is no report yet on linkage disequilibrium via 1000 genomes.  Since the frequency of the T-allele is low in African populations (1%) and about 10%-ish in other non-African populations, I guess the odds are that I’m an AA or AT.

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The article here:

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Are there events in your past that you hide from your friends and colleagues?  Are there parts of your body that you keep covered at all times?  You may think to yourself, “If people see this side of me, they won’t want to associate with me”.

Are you afraid of losing your job?  Losing your spouse or partner?  Creditors who who leave threatening messages?  A physical ailment that could be serious?

If you are an American, you are (statistically) likely to be overweight, over indebted and under increasing threat of losing your job and health benefits.  You may have friends that have “dropped out” of the social loop while being overwhelmed with these many adversities.  They themselves may feel stigmatized or too ashamed to face their usual circle of friends, and might rather stay out of touch.  Its an awful irony how feelings of shame and fear can cause our social relations to deteriorate just when we need them most.

Even if you haven’t dropped out, you may eat, drink or otherwise seek to numb these feelings of fear or shame.  But, deep down inside you may already be aware that by numbing your feelings of fear and shame, you also suppressing other emotions such as affection and joy – and thus undermining the social-familial bonds you are so afraid of losing.  Again, its an awful irony how fear, shame and anxiety can lead us to self-inflicted ruin.

Nevertheless, the grim reality remains.  Our bodies are unsightly, unfit and falling apart as we age.  Our careers paths are no longer certain in the new global economy.  We owe a lot of money and have barely the means to pay it back.  We do not have the resources to pay for old age.  Holy crap!  This is a dire view of the world hunh?!

What to do?  How to avoid the downward spiral of fear and anxiety?  Is there an upside to a deteriorating body?  a loss of career?  a down-shift to a much lower standard of living?

Check out this lecture by Dr. Brene Brown, who has carried out a great deal of social science research on this topic.  You will be amazed.  You will be uplifted.  You will begin to see that THERE IS an upside, and a way to break out of the cycle (unlike corporations, we won’t be getting a bailout).

Yoga and meditation practitioners may enjoy the parts of her talk on “self-love” and “courage” – a word whose origins lie in “cor” the word for “heart” and an ability to look inwardly and face the truth – a common theme, especially in Anusara yoga.

Note to readers:  Lately I’ve been focused on various personal and introspective themes, rather than the usual molecular-cognitive science-ology.  These themes set a base for exploring the basic biology of our emotional and cognitive lives and I’ll be digging into the brain-biology of these themes in the year to come.

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We hope, that you choke, that you choke.
Image by Corrie… via Flickr

Coping with fear and anxiety is difficult.  At times when one’s life, livelihood or loved one’s are threatened, we naturally hightenen our senses and allocate our emotional and physical resources for conflict.  At times, when all is well, and resources, relationships and relaxation time are plentiful, we should unwind and and enjoy the moment.  But most of us don’t.  Our prized cognitive abilities to remember, relive and ruminate on the bad stuff out there are just too well developed – and we suffer – some more than others  (see Robert Saplosky’s book “Why Zebras Don’t Get Ulcers” and related video lecture (hint – they don’t get ulcers because they don’t have the cognitive ability to ruminate on past events).  Such may be the flip side to our (homo sapiens) super-duper cognitive abilities.

Nevertheless, we try to understand our fears and axieties and understand their bio-social-psychological bases. A recent paper entitled, “A Genetically Informed Study of the Association Between Childhood Separation Anxiety, Sensitivity to CO2, Panic Disorder, and the Effect of Childhood Parental Loss” by Battaglia et al. [Arch Gen Psychiatry. 2009;66(1):64-71] brought to mind many of the complexities in beginning to understand the way in which some individuals come to suffer more emotional anguish than others.  The research team addressed a set of emotional difficulties that have been categorized by psychiatrists as “panic disorder” and involving sudden attacks of fear, sweating, racing heart, shortness of breath, etc. which can begin to occur in early adulthood.

Right off the bat, it seems that one of the difficulties in understanding such an emotional state(s) are the conventions (important for $$ billing purposes) used to describe the relationship between “healthy” and “illness” or “disorder”.  I mean, honestly, who hasn’t experienced what could be described as a mild panic disorder once or twice?  I have, but perhaps that doesn’t amount to a disorder.  A good read on the conflation of normal stress responses and disordered mental states is “Transforming Normality into Pathology: The DSM and the Outcomes of Stressful Social Arrangements” by Allan V. Horwitz.

Another difficulty in understanding how and why someone might experience such a condition has to do with the complexities of their childhood experience (not to mention genes). Child development and mental health are inextrictably related, yet, the relationship is hard to understand.  Certainly, the function of the adult brain is the product of countless developmental unfoldings that build upon one another, and certainly there is ample evidence that when healthy development is disrupted in a social or physical way, the consequences can be very unfortunate and long-lasting. Yet, our ability to make sense of how and why an individual is having mental and/or emotional difficulty is limited.  Its a complex, interactive and emergent set of processes.

What I liked about the Battaglia et al., article was the way in which they acknowledged all of these complexities and – using a multivariate twin study design – tried to objectively measure the effects of genes and environment (early and late) as well as candidate biological pathways (sensitivity to carbon dioxide).  The team gathered 346 twin pairs (equal mix of MZ and DZ) and assessed aspects of early and late emotional life as well as the sensitivity to the inhalation of 35% CO2 (kind of feels like suffocating and is known to activate fear circuitry perhaps via the ASC1a gene).   The basic notion was to parcel out the correlations between early emotional distress and adult emotional distress as well as with a very specific physiological response (fear illicited by breathing CO2).  If there were no correlation or covariation between early and late distress (or the physiological response) then perhaps these processes are not underlain by any common mechanism.

However, the team found that there was covariation between early life emotion (criteria for separation anxiety disorder) and adult emotion (panic disorder) as well as the physiological/fear response illicited by CO2.  Indeed there seems to be a common, or continuous, set of processes whose disruption early in development can manifest as emotional difficulty later in development.  Furthermore, the team suggests that the underlying unifying or core process is heavily regulated by a set of additive genetic factors.  Lastly, the team finds that the experience of parental loss in childhood increased (but not via an interaction with genetic variation) the strength of the covariation between early emotion, late emotion and CO2 reactivity.  The authors note several limitations and cautions to over-interpreting these data – which are from the largest such study of its kind to date.

For individuals who are tangled in persistent ruminations and emotional difficulties, I don’t know if these findings help.  They seem to bear out some of the cold, cruel logic of life and evolution – that our fear systems are great at keeping us alive when we’ve had adverse experience in childhood, but not necessarily happy.  On the other hand, the covariation is weak, so there is no such destiny in life, even when dealt unfortunate early experience AND genetic risk.  I hope that learning about the science might help folks cope with such cases of emotional distress.

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Image by Sbrimbillina via Flickr

Here’s a gene whose relationship to mental function is very straightforward.  If you hold your breath, your blood pH falls (more CO2 leads to more free H+ protons dissolved in your blood stream).  You also may become anxious, or worse if you are forced to hold your breath.  How does this process work?

Ziemann et al., in their new paper, “The Amygdala Is a Chemosensor that Detects Carbon Dioxide and Acidosis to Elicit Fear Behavior” [doi 10.1016/j.cell.2009.10.029] show that the acid sensing ion channel-1a (ASIC1a) gene is a proton-sensing Na+ and Ca++ channel – designed to activate dendritic spines when sensing H+ and drive neuronal activity.  Mice that lack this gene are not sensitive to higher CO2 levels, but when the protein is replaced in the amygdala, the mice show fearful behavior in response to higher CO2 levels.  Mother nature has provided a very straightforward way – ASIC1a activation of our fear center – of letting us know that no oxygen is a BAD thing!

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