Heart rate variability and social dysfunction

Editor's Notes

• #3: Before I begin I want to start with a quote from Martin Seligman who said… Today in next few moments that I have with you all I’ll be sharing the impact of this ‘below the neck’ activity on social dysfunction in mental illness.
• #4: Over a hundred years ago clinicians noticed that disorders of the CV system were associated with mood disorders
• #5: More recently, clinicians have noticed that social dysfunction commonly occur with illness
• #6: Something that is common to both of these associations is autonomic nervous system dysfunction.
• #7: Social dysfunction occurs across a range of disorders On a more global scale this impacts social relationships but on smaller level this is affected by problems in the expression and comprehension of emotion
• #8: Now anatomically the most important structure ‘below the neck’ that facilitates the expression and comprehension of emotion is the vagus nerve. The vagus nerve helps regulate autonomic nervous system activity through its influence on the heart and is a proposed mechanism for social dysfunction.
• #9: Heart rate is determined by the firing of the sinoatrial node – the heart’s pacemaker. The vagus nerve also acts like a brake which helps regulate social behavior
• #10: The vagus nerve.... Social cohesion was crucial for the survival of our ancestors Poor social behavior not ideal for survival The polyvagal theory proposes the ANS has evolved to support survival, reproduction and social engagement An important feature of this theory is the bidirectional influence of the brain on the body The most recent development of the ANS is vagus nerve The vagus nerve facilities engagement with the environment through its inhibitory influence on the sinoatrial node The vagus acts like a brake The vagus nerve also helps regulate social behavior As well as innervating the heart, the autonomic nervous system also innervates parts of the face that are crucial for social communication
• #11: Poor vagal control affects the ability to express emotions. Ever notice when your voice wavers when you ’re speaking in public? That’s due to reduced vagal control of your laryngeal and pharyngeal muscles which regulates the pitch and control of your voice Vagal tone is also important in the control of the middle ear muscles which help with the perception of mid-frequency sounds (i.e., human voices) Vagal control is also important for the expression of emotions via facial muscles. If you can ’t express emotions effectively, people around you can’t tell what you’re thinking or feeling or what your intentions are.
• #12: In a safe enviroment the vagus nerve promotes ‘ apporoach ’ behaviors and facilitates social interaction
• #13: Specifically, the PNS inhibits HR via the vagal brake. Greater PNS stimulation slows HR. This can be demonstrated by the simple act of breathing out slowly
• #14: However during threat situations, social interaction is near the bottom of the priority list
• #15: A release of the vagal brake stimulates HR which discourages social interaction
• #16: The vagus nerve....
• #17: We can also use a traditional electrocardiogram or a pulse oximiter – anything that can measure the cardiac cycle accurately and at a relatively high resolution
• #18: R-R intervals are a good approximation of the cardiac cycle More variation in R-R intervals is indicative of greater parasympathetic nervous system activity Healthy cardiac activity is associated with high variability But why is high variability a good thing? Let’s consider how a tall building is made…
• #19: Here ’s surfers paradise which isn’t too far away Right in the middle you can see the Q1 building – tallest building in the southern hemisphere If you ’ve ever been near the top of a tall structure you may notice a slight sway in high winds The top can sway up to 6 meters in any direction Without this sway the building would be put under some serious stress
• #20: If you ’ve ever been to the top of a tall structure
• #21: Social dysfunction commonly reported in depression So is HRV reduced in those without CVD? Some studies said yes, some studies said no… We conducted a meta-analysis to determine if HRV is reduced We found that HRV was reduced in depression and that is depression severity increases, HRV decreases. We published this finding in Biological Psychiatry Anxiety comorbidity can be as high as 50% in depression A follow-up study under review from our lab investigated the impact of comorbid anxiety on HRV
• #22: Consistent with our meta-analysis, HRV was reduced in MDD compared to controls However, 50% of MDD is comorbid with anxiety so we wanted to see if this was driving the association Perhaps the original findings were influenced by comorbid anxiety?
• #23: MDD with GAD significantly reduced We suggest that the greater reductions in MDD with GAD is due to ‘ruminative’ and chronic nature of GAD which may lead to more sympathetic activity PTSD and PD are generally more situational so stress on the ANS is occurring less Not due to MDD severity
• #24: Social dysfunction also common in alcohol dependence Some contradictory research in the literature on whether dependence reduced HRV or if it’s due to intake A group from the Netherlands argues that it ’s consumption (not dependence). Considering the role of HRV in self-regulation we hypothesized that HRV is still reduced in alcohol dependence Looking at the literature there ’s mixed results – some said yes and others said no Using meta-analysis we pooled together the results of 6 studies that fulfilled the inclusion criteria of our analysis
• #25: Overall, the summary effect size of 6 studies suggests that HRV is reduced in dependence Not due to CVD or consumption of alcohol
• #26: Now that we have established that a number of disorders, known for problems with social dysfunction, have reduced HRV we wanted to investigate if HRV was related to emotion recognition Specifically, we looked at the reading the mind in the eyes which indexes ‘mind reading’ of others, or figuring out the thoughts or intentions of others. According to the Polyvagal theory, those with greater parasympathetic dominance will display more ‘approach’ behaviors, which includes the ability to determine the emotions of others Originally developed for autism, this can also be used in healthy populations There are a number of covariates that can influence HRV including gender, age and physical activity. That is, older males tend to have lower HRV which is consistent with the epidemiology of CVDs
• #27: What do you think this man is thinking or feeling?
• #28: As you can imagine, interpreting and encoding social cues is an incredibly complex process that our brain ’ s accomplish without us even really consciously thinking too much. You didn ’ t really have to ‘ think ’ that this man is upset - one look and you just ‘ know ’ .
• #29: We found that after accounting for covariates known to influence HRV, HRV is associated with performance in the RMET First study to provide evidence that resting state ANS function is related to social cognition
• #30: Earlier work in our lab has established that OT increases emotion recognition so does a single spray of OT increase HRV To test this we performed a randomized double blind crossover trial of OT on HRV 12 participants were either randomized to OT or placebo, received the spray, then we measured HRV 45 minutes later Participants then came back a week later and received the opposite spray, follewed by and ECG recording 45 minutes later
• #31: Acute oxytocin administration appears to increase HRV in healthy controls This emerged after only after a single administration of oxytocin As well as using OT to increase HRV, we have also tested breathing biofeedback for the increase of HRV
• #32: Last year in the lab we had a student who was a semi-professional musician who wanted to investigate the efficacy of HRV BF on performance anxiety in musicians. It ’s not uncommon for musicians to take beta-blockers before performances to reduce nerves but these can have side-effects As well as OT, biofeedback breathing exercises has the potential to increase HRV. Involves slow breathing, 6 breaths per minute (normal, spontaneous breathing about 15 breaths per minute) Biofeedback involves training in deep abdominal breathing and practice Known to reduce anxiety and depression in early studies People either did biofeedback or ‘sham’ breathing
• #33: As well as increasing HRV, measures of anxiety in the intervention group reduced. This emerged after only after a week of treatment