What percentage of people have chronic post-surgical pain?
Roughly 7%.
What are some reasons for interindividual variability?
Organismic (nature) - genetic backgrounds, sex, psychological traits, age, circadian rhythms, etc.
Environmental (nurture) - past experiences, gender, psychological states, diets, social factors, etc.
What is heritability and what is the best way to study it?
Heritability is the proportion of the overall variability that is inherited. The best way to study it is by comparing identical and fraternal twins.
What is a monogenic disorder?
A disorder due to the dysfunction of one gene. The dysfunction can either be a loss or a gain of a function. These disorders are incredibly rare.
How much does biological heritability make up for in pain sensation?
Biological heritability makes up about 40% of variability in pain sensation.
What is OPPERA?
OPPERA was a prospective study published in Pain of people with temporomandibular disorder (unexplained jaw pain). The researchers enrolled 3000 in the study, none of whom had TMD, and waited until they did develop it. About 300 people developed TMD over about a decade. The genes did not predict the development of TMD, but high scores on the PILL Global Score, and SCL 90R somatization subscores. Those who scored higher on those were almost 2.5 times more likely to develop TMD.
What is somatization?
When a person pays attention to a sensation in their body and ruminates on it.
How much more likely are women to say they’re in pain than men?
5-10%
What is one difference between sexes in pain mechanisms?
Males are using microglia and females are not.
When does pain prevalence peak in each sex?
The prevalence of pain in men peaks at around middle age and decreases as age goes up. In women it continues to rise during middle age and plateaus as age goes up.
What is the disparity between black children and white children in pain care?
About 20% more of white children are offered pain care and treatment than black children.
What time of day does pain peak at?
Mornings, with the exception of osteoarthritis which peaks in the evening.
What are some things that increase your risk of developing chronic pain?
Being out of work, a BMI over 30, being married, being divorced.
What is the best way to deal with a friend or partner who is in pain?
Coddling the person makes the pain worse, but distraction makes the pain better.
Who discovered the placebo effect and how?
Henry Beecher discovered the placebo effect as a medic in WWII. He ran out of morphine but decided to tell the people he was working on that they were receiving morphine when they were only receiving a saline drip. They reacted as if they were receiving morphine even though they weren’t.
What percentage of people in a study will respond to the placebo effect?
About 1/3 or 33%.
What is regression to the mean?
Regression to the mean talks about how pain levels vary with individuals overtime. You may be more motivated to make a doctor’s appointment or sign up for a clinical trial when your pain levels are high, but because of that, your pain levels are more likely to go down after the doctor’s appointment. Not because of what your doctor gave you, but more so because low and levels of pain will eventually even out and regress to the mean.
What is the placebo effect a combination of?
Conditioning, expectation, and desire.
What are some factors that affect the placebo effect?
- subjectivity vs objectivity of the measure
- the nature of verbal suggestions
- previous experience
- belief/expectation/desire of the patient and the clinician
- patient-clinician interaction or the “therapeutic context”
What is the most important trait regarding placebo?
Optimism
What is the neurochemistry behind the placebo effect?
It is due to the release of endogenous opioids as it can be blocked by naloxone.
What is the nocebo effect?
The same thing as the placebo effect, just in reverse.
What does ACTION do?
They are a public-private partnership between the FDA and a consortium of drug companies. They are looking over clinical trials and trying to figure out why they are failing.
What chemical produces the nocebo effect?
Cholecystokinin
