Computational Psychiatry Flashcards
What is computational psychiatry?
Using approaches from computational neuroscience to understand and treat mental health problems
What are the 2 categories of computational psychiatry?
Theory-driven
Focused on understanding underlying mechanisms
Builds mathematical models of psychological/neural processes and how they go awry
Data-driven
More focused on practical utility (e.g., diagnosis/prediction)
Applies computational approaches to find patterns in data in service of this aim
What is a computational model?
They take hypotheses about the mechanisms underlying mental health problems and put them into a mathematical form
This is useful because it makes it easy to quantify precisely how well our data matches our hypothesis
What is the Rescorla Wagner model?
Proposes that we update our expectations based on weighted prediction errors
(not only most recent outcome; but gradually update our expectations based on proportion of prediction error)
Prediction error equation
= outcome - expectation
What can we use to assess learning irl?
Ask people to complete cognitive tasks where they learn to associate stimuli with an outcome
(find people have wide range of learning rates/weighting)
What was found about learning and schizophrenia?
A number of studies have used this exact approach to show that people with schizophrenia learn more slowly than healthy individuals (e.g., Martinelli et al., 2018; Collins et al., 2014)
This might suggest that people with schizophrenia have difficulty learning about the world around them
What was found about learning and anxiety?
In contrast, it seems people with high levels of anxiety tend to learn faster (higher learning rate) than people low in anxiety (Huang et al., 2017)
suggest anxiety tend to be faster to update their expactations; linked to tendency to assume negative outcome
What was the anxiety experiment?
Subjects choose one of three options, trying to get the biggest reward
Each option has a different (hidden) probability of reward
Learning which option is most likely to give a reward results in greater rewards
What was tested and found by Aylward 2019?
Participants choose one of four options, trying to collect reward and avoid punishment (negative reward)
Each option has a different probability of reward and punishment which varies over time
They found that people with anxiety have higher punishment (but not reward) learning rates
May explain how people with anxiety develop a negative view of the world around them
What are the 2 systems for making decisions?
Goal directed vs habitual decisions
What are goal directed and habitual decisions?
One involves prospective thought about the outcomes of our actions – this “goal-directed” system is more demanding, but more accurate
One involves learning based on the immediate consequences of our actions – this “habitual” system is simpler, but less accurate
What is thought about decision making in OCD?
One hypothesis is that there is an imbalance in these systems in conditions like OCD
People with OCD rely on habitual decision-making, which encourages repeated compulsive behaviours
What was found about habits in OCD by GIllian et al 2011/14?
This hypothesis found a lot of support from studies using cognitive tasks that assess how habitual or goal-directed people are in their decision-making
In general, people with OCD tended to rely on habits to a greater extent than people without OCD (Gillan et al., 2011; 2014)
But what did Alvarez 2016 find out about this?
However, a problem emerged
Similar results were found in studies looking a range of other conditions, such as social anxiety, psychosis, eating disorders, autism…
Clearly a reliance on habit wasn’t specific to OCD
What did Gillian propose instead?
Gillan et al. (2016) sought to solve this conundrum
They hypothesised that perhaps an over-use of habitual decision-making might be related to compulsive symptoms, which are in people with all types of mental health problem
They gave people a battery of questionnaires measuring a variety of symptoms, and extracted 3 symptom dimensions that cut across traditional diagnostic categories:
They found that symptoms of most conditions were linked to an increase in habitual decision-making
This replicated what had been in observed in prior studies (except social anxiety!)
Again, this suggested that excessive habitual decision-making wasn’t specific to OCD at all
What are the 3 symptom dimensions that cut across traditional diagnostic categories?
Anxiety & depression
Compulsivity & intrusive thought
Social withdrawal
What was only found to be linked to increased habitual decision making? What did this suggest?
“compulsivity and intrusive thought” was linked to increased habitual decision-making
This suggested that the reason so many conditions are associated with habitual decision-making is because this symptom dimension is present in all of them
This ultimately supports the hypothesis that compulsive behaviours are linked to increased reliance on habits
What would be clinically useful to detect in AD?
deterioration?
What did Kambeitz find about depression, what are the limitations of this?
accuracies of 75% depending on data modality
but small samplies and misestimation of acccuracy and publication bias
What would be useful to predict in depression?
Treatment response
What did Cohen et al 2021 find, what are the limitations of this?
78% accuracy (Cohen et al., 2021)
However, these studies also use small samples
Additionally, even if effective neuroimaging is potentially too expensive for real-world clinical use
What did Wager 2013 sought to develop
Objective measure of pain using machine learning
to decode subjective pain rating successfully
Mental health problems aren’t unitary concepts instead
comprise multiple subtypes
(e.g. depression highly heterogenous condition)
