Lecture 2: Utility

Now we have discussed the general framework of the pros and cons of choices and we assume that patients are motivated to make a decision.

The difficult part comes out: how do they make a comparison between different options? Can these options be scored? From the point of economics, there is a way to score each option and make a comparison. Such a ‘score’ is the utility of an action. We may consider utility as a general currency to measure if an action will bring good or satisfying outcomes. And economists assume that the goal of our behaviour is to maximize utility, i.e., we search for the actions that will bring good outcomes. It should be noted that our action also reflects the utility that we endow an option. That means we can judge which choices have higher utility by looking into our preference in making a decision.

For example, patients may have two options for their Friday evening. They may enjoy themselves with some music or see the dentist for some mild toothache. If they decide to see the dentist, that means the option to have toothache relief have a higher utility, i.e., a better choice to maximize goodness or satisfaction. You may say that the pleasure from music and pain relief is both rewarding, but they are incomparable because they are different feelings. But we know one is granted higher utility than another, simply according to the preference from the decision-maker. Now let’s go back to a clinical scenario. Before making a decision, patients want to choose an option that will benefit them more.

The judgment is usually not straightforward because there can be uncertainty in the outcome of an option. For example, patients may decide to receive surgery to relieve trigeminal neuralgia. The surgery may or may not succeed. Such a medical decision is difficult because there is always some degree of uncertainty in the outcome. We call it a decision under risk, here risk means the uncertain nature of decision-making. There have been many researchers studying the role of risk, and one of the influential theory is the Expected Utility Model, which states that the decision-maker would consider a combined effect from the benefits of an outcome and the probability that the outcome will appear. For example, there are two plans for treating periodontal disease.

The hypothetical treatment ‘Bio-photon-field’ may have a great effect if it works, but it does not guarantee to work. In contrast, the traditional periodontal treatment may offer a more reliable effect of treatment. So patients need to consider the probability aspect of a choice because of the uncertain nature of medical decision-making. From the point of cognitive neuroscience, when we say something is rewarding and want to pursue it, the brain is dealing with two aspects of information. One of them relates to the emotional aspect. The brain evaluates how pleasant the outcome is, i.e., the hedonic value, of an option. Another of them relates to the motivational aspect. The brain evaluates the inventiveness to obtain the outcome, i.e., the salience of an option.

In daily language, these two aspects of information relate to the feeling of liking and wanting, respectively. There is also a critical mechanism for learning based on reward. Remember in our general framework, people will modify their actions according to their prior experience. Exactly speaking, our future decisions are usually guided by the mismatch between our expectation and the actual outcome. We learn from our experience when there is something special. For example, if we do something for a gift under our expectation, we will do the same thing again for the gift.

However, if we fail to get the gift, we may consider changing our way next time, i.e., we have learned to adopt a new strategy for the gift due to the mismatch between our expectation and outcome. Researchers have found that the neurotransmitter dopamine plays a key role in the learning process. Interestingly, the change of dopamine release also relates to unexpected results. In both cases, dopamine is associated with a mismatch between expectation and outcome.

Except for dopamine, researchers found that opioids, which are generally considered as an analgesic agent, play a key role in the processing of hedonic value, which relates to the feeling of ‘liking’. Dopamine, in contrast, plays an important role in the processing of incentive salience, which relates to the feeling of ‘wanting’. From this point, we may think the brain regions in charge of the release of the neurotransmitters may be the centre for motivation and reward processing. But things are more complicated. For example, dopamine release is critical to the mesocorticolimbic circuit, which consists of many cortical and subcortical regions.

Neuroimaging studies reveal that activation of some brain regions, such as nucleus accumbens, has been consistently found when people feel good, regardless of the type of reward. However, the activation of the nucleus accumbens should be considered as part of information processing in the whole mesocorticolimbic system, rather than a stand-alone event. It has been widely accepted that our brain is sensitive to mismatch, or the situation being ‘out of my expectation’. And therefore, during clinical practice, we should be aware of not just patients feelings of the outcome of treatment but also their expectations of the treatment. It is not uncommon to find patients feel disappointed because the treatment outcome does not meet their expectations.

In this case, what we need to negotiate with patients may be their expectations – which would be too unrealistic. That’s why we need to listen to patients carefully about what they expect from our treatment. The key to patient-dentist communication is to set a reasonable goal and minimize patients’ over-expectation from dentists.