Not sure if this helps, but I decided to share this post with my spouse, whose academic field happens to be the neuroscience of individual differences in learning, motivation, and reward, because he's always complaining that dopamine signalling is being misrepresented in popular discourse. This was his reply:
"So, itâs unlikely that there is simply ânot enough dopamine,â and getting a treat or eating a special food is not going to magically fix that by just âadding dopamine.â Treats can trigger dopamine release, but the key issue isnât the absolute amountâitâs how and where dopamine is signalling in the brain. What matters is the timing, location, and whether that signal is effectively received. What dopamine does can also vary depending on where in the brain it is acting.
Itâs also important to note that dopamine is not a pleasure molecule. Other naturally occurring molecules in the brain (e.g., opioidsâwhich share structure with drugs like morphine or heroin) are more directly related to pleasure. In terms of reward, dopamine levels very quickly increase (especially in an area known as the nucleus accumbens) when a reward is unexpected or surprising. However, we eventually learn that certain things predict reward (we call these Pavlovian conditioned stimuli, or cues). Once these are learned, it is the cues that trigger dopamine release, and the reward itself no longer produces much dopamine. Therefore, dopamine is a reward-learning signal, at least in the nucleus accumbens.
Now, some cues are especially attention-grabbing or meaningful. These cues can increase dopamine even more. This can happen to an excessive degree, to the point where it becomes problematic, causing us to act in certain ways even when it is not beneficial. This happens in addiction, where cues can excessively increase dopamine and motivate someone to consume drugs. It can also happen in other disorders, where cues can become overly meaningful and even evoke fear (this sometimes happens in schizophrenia). We refer to how much the brain tags something as important or attention-grabbing as its level of salience.
Importantly, just because dopamine levels increase doesnât mean that it has any consequence. For dopamine to communicate something, the signal needs to be received. There are different types of dopamine receptors, and some of these can have opposing actions (some can be excitatory and others inhibitory). In some mental health conditions, people may not have enough of certain receptors, or the balance between these receptor types might be altered; this affects how well the dopamine message can be communicated.
In addition, the brain can be very effective at clearing away dopamine after it is released. In many mental health conditions, including ADHD, this clearance process may be altered. This doesnât necessarily mean it is always faster or slower, but it can affect how long and how strongly dopamine signals persist. If the signal is too brief or poorly timed, it may not have much impact. So even if dopamine is released, the message might not effectively get through. Medications for ADHD can help, in part, by strengthening or prolonging dopamine signalling, making it more likely that these signals are successfully communicated.
So what is this message? I previously mentioned reward learning, but dopamine is important for other behaviours and psychological states as well. For example, in an area of the brain called the prefrontal cortex, dopamine (alongside other messengers) helps us to be flexible, switch tasks, plan ahead, and inhibit unhelpful actions. In other brain regions, dopamine helps us develop habits, where behaviour can become more automated.
Bringing this back to the original point, the issue with executive dysfunction is unlikely to be simply ânot enough dopamine,â but rather that dopamine signalling isnât effectively tagging certain tasks as important, rewarding, or worth doing. This can feel like a lack of motivation, but it reflects how the system is functioning, not just the total amount of dopamine available.
Finally, it is important to note that many of the behaviours Iâve mentioned involve acting in a certain way. Dopamine is also critical for regulating movement; this is why movement is disrupted in disorders like Parkinsonâs disease, where dopamine production is lost. More broadly, dopamine plays an important role in helping us adjust our behaviourâbeing flexible, adapting to changing circumstances, and updating our actions when situations or goals change."