Lecture 21 - Schizophrenia Flashcards
What are psychiatric illnesses?
Ex: schizophrenia and autism
- Heritable, common (4%) and harmful to reproductive success mental disorders
Why are the genes to mental disorders not put under evolutionary pressure? Why are they recurrent when they are harmful to reproductive success?
- Hundreds of common gene variants have been associated with higher risk of having schizophrenia, bipolar disorder, depression, autism, OCD and ADHD.
- It seems to be a certain combination of these genes that create the risk factor for these disorders, whichever the disorder. Which is why mental disorders have a high rate of comorbidity.
What is comorbidity?
- It’s when you have more than one diagnosis at the same time.
- Extremely common with psychiatric illnesses.
Are mental disorders discrete, unitary diseases?
It doesn’t seem like it.
- There is too much heterogeneity within diagnosis categories, comorbidity across categories and continuity with normally for mental disorders to qualify as discrete, unitary diseases.
What are psychiatric illnesses diagnostic categories useful for?
They are useful for describing clusters of symptom that tend to appear together.
What do the gene variants associated with increased risk of mental illness regulate in the brain that explains why they haven’t been selected out?
They regulate brain development and neural plasticity.
Their expression in the brain gives rise to altered patterns of neural activity throughout the brain.
What is mutation-selection balance theory?
It is a theory that says that mental disorder susceptibility genes are continually being selected out through evolution, but new mutations keep arising.
How many protein-encoding genes does the human genome have?
20 000 protein-encoding genes
- About half of them are expressed in the brain at some point
What is the slight reduction fitness?
It’s a reduction in overall fitness that arose within the last 100 generations with the arrival of industrialization and modernity. With it comes some gene mutations.
What has evolution not buffed over slight mutations?
- The brain seems to be buffing the biggest mutations, the ones that really compromise the survival and reproductive abilities. Slight mutations are seen as less important or even not affecting enough to be considered very important to get rid of.
But these slight mutations then accumulate in the population, and these slightly bad mutations can collectively compromise the evolved interactions of everything in the brain.
How can one twin have schizophrenia and the other not?
There is so much unavoidable randomness at the molecular level impacting the brain development that it’s simply up to chance how the brain will develop, even in twins.
What is neurodevelopmental robustness?
Basically, it is the clarity of the genetic instructions of the genome. If the instructions are clear, precise and neat, the brain has an easier time following them and making sure everything goes to plan.
What does body symmetry have to do with robustness of the underlying genetic instructions?
- The two sides of the body develop independently from the same set of genomic instructions. Therefore, if the instructions are clear, the body should be symmetrical, if the instructions are a bit confusing or open to interpretation however, the person will be a bit more asymmetric.
How does body symmetry slightly correlate with intelligence, physical attractiveness and physical health?
Hundreds of gene variants correlate with a very small statistical increase in intelligence. Some of these gene variants associated with intelligence overlap with the gene variants associated with physical attractiveness, physical health and longetivity.
Are thought to be indicative of neurodevelopmental robustness
What are the best ways to maintaining a healthy brain and body in order to reduce the risks of mental illnesses?
- Stay active, physically + mentally
- Eat well
- Reduce stress, lower blood pressure
- Maintain good sleep habits
- Limit alcohol intake and avoid tobacco and hard drugs
By identifying …….. , researchers hope to develop new treatment and prevention strategies.
FILL IN THE BLANK
The gene variants and neural circuit disruptions associated with mental illness.
Can we edit genes in living breathing humans already born?
Editing genes in a living person is very difficult cause there are trillions of cells in a person. To fix the DNA in every cell would be extremely complicated. There are trials going on, but we are not yet at a solution yet
What kind of new pharmacological treatments in mental illness are people hopeful for?
Pharmacological treatments that directly target intracellular signalling cascades in precise parts of the brain and that do not target neurotransmitter signalling.
