Alcohol and the reward system
Something remarkable happens when we experience a craving for a drink and then take one. We lift the glass to our lips and swallow and then get an immediate sense of ease and comfort; the extraordinary thing here is that this sensation is immediate. It would take several minutes for any alcohol swallowed to be absorbed in the stomach and then carried through the blood to our brain, yet we get the “aaaahhhh!” sensation immediately. It is not alcohol that causes this sensation; this is the reward system in operation. The sense of ease and comfort isn’t caused by the alcohol we just swallowed but by a chemical called dopamine which is released in our brain by the reward system as the reward for taking the action encouraged by a craving.
Our brain and the nerves that connect it to our skin, muscles, and organs are made up of billions of neurons (nerve cells). Dopamine is one of a group of chemicals called neurotransmitters. These pass signals from one neuron to the next and neurotransmitters work at the connections between neurons which are tiny gaps called synapses. When a molecule of a neurotransmitter crosses a synapse it instructs the next neuron what to do and this happens extremely quickly; signals move through the body’s nervous system at about 400 kph (250 mph).
The reward system performs three specific tasks within the brain and dopamine is the neurotransmitter that activates them. When we experience something particularly good we feel joy, delight or excitement and the reward system notes this. It releases dopamine down one nerve pathway which makes the brain remember the current circumstances and surroundings and this becomes a reference memory; these reference circumstances are known as ‘triggers’. The next time the circumstances of a trigger are encountered then dopamine is activated in another pathway, and this pathway creates a feeling of wanting or longing for: a craving. Finally, if we act on that motivating feeling then dopamine is released along a third pathway and we experience this as a sensation of joy, happiness, or relief. Dopamine is responsible for all of these actions but it has many other roles in the brain and most significantly it is responsible for creating feelings of joy or euphoria regardless of what part of the brain calls for it. But one of the effects of alcohol in the brain is that it artificially causes dopamine to be released. This makes us feel good when we drink and the reward system therefore steps in and establishes a trigger: “That was good, do it again”. Alcohol always causes dopamine to be released, so the reward system creates a new trigger every time we drink alcohol in new circumstances.
The actions of the reward system, once established, remain in place forever. This is a feature of how brains work: what has become known cannot become unknown. Once a trigger is formed then it can never be removed and neither can its associated motivating urge or the rewarding surge of well-being. But while these components become permanent on formation their vigour can be changed.
A single fact or detail is stored in the brain in a group of connected neurons. These groups of connected neurons behave in one respect like a muscle in that just as a muscle gets stronger and faster with exercise so does a group of neurons that fire together. Neurons that work in groups like this are called neural pathways and the more often a neural pathway is traversed then the faster and firmer it becomes and this speeding up is very considerable. New triggers get formed when we meet a new circumstance that we enjoy, but if we meet a circumstance that is already known as a trigger then the neurons encapsulating it are activated and it becomes stronger and faster; the more often we access a trigger the faster and firmer it becomes. Triggers that are accessed frequently become lightning fast and are found before other triggers related to similar circumstance. But not only does a regularly exercised trigger become quicker it also gains vigour; it releases more dopamine. The more often we drink in the circumstances of a particular trigger then the more powerful its three actions become; the fixation of the memory “that was good, do it again”, the craving, and the rewarding sense of wellbeing. But there is something else that makes a trigger operate more vigorously, and that is closeness.
Evolution has made the reward system impart urgency to doing things that benefit survival. However, something beneficial like a food that is available now might not be found again for some time, so our brain encourages us to take advantage of the opportunity while it is present; but it also makes us do so efficiently. If for example there is a bird in the middle of a field of nourishing berry bushes then there are berries all around it. There is food in every direction but it would be inefficient in terms of energy use for the bird to pick berries randomly from all corners of the field. So the reward system evolved to minimise energy use by encouraging the bird to take the closest ones first. The motivating urge released by a trigger is far stronger when its subject is close than when the subject is distant. In terms of alcohol this means that the craving to drink is far more powerful when we are close to it. But it also means that if we begin drinking in a location where alcohol is freely available then we experience another powerful craving for a drink as soon as we have finished our current one. Once we have started drinking in a place where alcohol is close by and available then our reward system demands that we continue. This encourages us to drink more and to drink for longer than was intended when we first arrived at the location.
Every new circumstance in which we drink forms a new trigger and our brain constantly scans incoming information looking for triggering circumstances that have been met before. Directly seeing or smelling the subject of a trigger will make that trigger fire, but triggers are by no means limited to this direct identification. A flying bird may not be able to see the actual berries on a bush, but it can see the bush. And the bird may be so far away that it can’t even see the bush, but it can see the terrain that bushes of this type grow in. The bird forms triggers for bushes of the correct form and for terrain that supports this type of bush, and we do exactly the same with alcohol. Yes, we form a trigger to drink when we see or smell alcohol, but we also form a trigger for a place at which we’ve drunk previously, and we also form a trigger for the road that leads to that place. Over an extended period we accumulate hundreds and hundreds of triggers that encourage us to drink. The cravings brought on by these triggers grow stronger each time we act on them and they grow stronger as we draw closer to the trigger’s location. But the reward system can be fooled regarding closeness. The reward system evolved before the existence of pictures, photographs, television etc. and it evolved before our human ability to visualise and imagine. To the reward system all of these things are recognised as real. It cannot distinguish between a glass containing alcohol and a picture of a glass containing alcohol; both cause cravings to be launched. Photographs of alcohol and images of people drinking will bring on cravings and even imagining those things will cause the related triggers to fire. We can bring powerful cravings on ourselves by simply daydreaming about drinking.
Whether or not drinking becomes compulsive rather than chosen depends on the vigour that the drinking triggers acquire. The intensity of a craving and the amount of dopamine reward that we get in response to a craving is determined by the number of times that this trigger has been successful in delivering alcohol and also how close we are to the circumstances of the trigger. The reward system encourages us to drink more and it encourages us to drink more often, and if this continues then the triggers strengthen without limit and we become addicted. But everybody has this reward system, so how come that everyone that ever has a drink doesn’t become alcoholic?
Triggers exist to encourage some behaviours and discourage others, but a single subject can have multiple triggers for different circumstances. For example, we might have two triggers for lemons; we may feel the urge squeeze some lemon juice over fried food, but we would recoil strongly from the suggestion we should eat a whole one. Just like the example of the lemon most people have some triggers that encourage them to drink, and other triggers that urge them not to. It is the balance of these competing triggers that (most often) prevents them from drinking unwisely. Normal drinkers have triggers motivating against drinking too much, and against drinking at the wrong times. They have triggers linked to the discomforts of drinking too much; hangovers, vomiting, and loss of control, and they have triggers relating to the unwanted consequences of drinking; failing to meet important obligations, drink-driving dangers and so on. But these alcohol-avoiding triggers do not form properly in some people and the absence of these has catastrophic consequences.
The reward system encourages us to do some things but it discourages us from doing some others and how it handles conflicting triggers is central to how addiction forms. If I stand on a hilltop where I can see a long way, and I also overlook a large lake or sea, then I will get a strong sense of wellbeing; this is a dopamine surge released by the reward system. My reward system has responded to three triggers; I have put myself close to plenty of water (vital to our survival), I am above the surroundings (therefore safer from predators) and I can see a long way (also, safer from predators). These three independent circumstances all activated triggers and I am rewarded for this.
However, if that same hilltop I stand on is a cliff edge then a different trigger will fire and the others will not. The risk of falling is present, and fear is induced to motivate me to move away. Even though I am still in that elevated position where I can see water and I can see a long way I do not experience any sense of wellbeing, I only experience the fear. This is because the trigger to make me step back from the edge is stronger than the triggers saying “here is good”, and when triggers compete then the most powerful one prevails. We don’t feel the effects of the more powerful trigger above those of the weaker triggers, the other triggers are completely dismissed along with any reward that they would have launched. But if competing triggers have similar strength then the triggers that discourage harmful behaviours prevail over triggers promoting beneficial behaviours. The evolutionary origin of this preference is quite simple: it is better to miss even the finest of feasts than to risk being caught by a predator. However, the extent to which we prefer triggers discouraging harmful actions over triggers encouraging beneficial actions is not entirely fixed across all society; it varies from individual to individual. Animals that place higher importance on the triggers encouraging avoidance of danger than they do on the triggers encouraging beneficial behaviours tend to be more timid, and those that place less importance on the harm-avoiding triggers tend to be more adventurous. This weighting is a characteristic of the individual and it is as fixed as our height; it is predetermined at birth and cannot be changed. Individuals that prefer risk avoidance assign greater strength to triggers discouraging potentially harmful behaviours, whereas individuals that are more inquisitive, independent or adventurous assign greater strength to triggers associated with beneficial outcomes. Most addicts are in this second group. We assign much greater strength to drinking triggers than we do to drink-avoiding triggers and this has a profound influence on our overall drinking behaviour because in us it is far less likely that a drink-avoiding trigger will ever prevail when triggers compete. But there is another characteristic that can prevent many alcohol-avoiding triggers from forming at all.
Just as a trigger gains significance on closeness a similar thing happens in relation to closeness in time: we are attracted to partaking of something beneficial now rather than coming back for it later. The evolutionary origin of this is obvious: take the food now because it might not still be there when we come back. But what if the reward later would be larger than the reward now? How we behave under this circumstance is famously demonstrated by “the marshmallow test”:- Put a marshmallow in front of a child, tell them that they can have a second one if they can go 10 minutes without eating the first one, and then leave them alone. Some children will resist the urge to eat the single marshmallow knowing that there will be two later, but some will not. The key attribute demonstrated here is that the children that won’t wait the ten minutes devalue the extra benefit of another marshmallow over time far more aggressively than the others. These children favour “now” far more strongly than “later” and people having this internal preference form far fewer alcohol-avoiding triggers than everyone else. The extra benefit is valuable for these people, but if that advantage is significantly in the future then it is disregarded in favour of the immediate opportunity. But it isn’t only advantageous things that get discounted over time, disadvantageous ones do too. In terms of drink-avoiding triggers this means that for these people the later penalty of a hangover is diminished to the point that it isn’t significant enough to form an alcohol-avoiding trigger because it is too distant in time. People that are highly motivated by “now” rather than “later” form far fewer alcohol-avoiding triggers as the adverse consequences, though they may be severe, are most often encountered significantly after drinking rather than at the same time or very close to it. Frequently accessed neural pathways become firmer and faster, and with regular drinking we increase the power of the drinking triggers that we drink in response to. But if our personal characteristics devalue the significance of the repulsing “don’t drink now” triggers then when we come to an occasion where we are triggered to both drink and to avoid drink then the weaker trigger is usually the drink-avoiding trigger, and it is dismissed. When this happens we strengthen the trigger that encourages drinking because it was successful but we also weaken the trigger that discourages drinking because this trigger failed to deliver its objective. At the same time as our drinking triggers gain in strength the alcohol-avoiding triggers become weaker, and over time they reach the point that they are almost never more potent than a drinking trigger; so motivation from the reward system to avoid drinking very rarely occurs. This bias towards favouring drinking triggers over drink-avoiding triggers becomes more marked as we continue to drink, and this causes a similar bias to develop in our memory.
One of the actions of a drinking trigger is that when we act on its craving then we get a rewarding pulse of dopamine, and the stronger the trigger has become then the stronger is that reward. But that big dopamine surge does something else as well, it reinforces the memory “that was good! do it again” We don’t simply reinforce this message we do it very strongly because that memory is being impressed by a powerful dopamine surge, and over time the idea that drinking is a good thing becomes incredibly deeply learned. But since we only build a few drink-avoiding triggers, and since these triggers don’t succeed very often, we only very rarely reinforce the opposing memory “that was bad! don’t do it”. Even when we do reinforce this memory we only do so weakly because our drink-avoiding triggers are not very powerful. Failing to record the bad experiences as strongly as the good experiences means that our perception of alcohol becomes hopelessly biased. When we think of drinking then our first recall is always of good and happy times, never bad ones, and as our reward system becomes more and more heavily biased in favour of drinking so does our memory. “Drinking is good” becomes the thing we know more confidently than anything else and the idea that drinking is bad is a mere murmur by comparison.
Normal drinkers build strong triggers and memories relating to bad drinking experiences, but we don’t. We don’t build the alcohol-deterring triggers, and we only have weak memories of bad experiences. This inability to properly recognise the downsides of drinking means that we are still encouraged to drink when others would refrain. For example alcoholics will drink with complete disregard to the fact that a severe hangover will follow; our reward system does not encourage us to avoid this outcome. We are aware that we are drinking enough to get a hangover, but when this thought arrives (if it arrives at all) it comes only as simple information; it has no accompanying compulsion to refrain, stop or slow down. We do not have a trigger that says “that’s enough now”, we only have a pale memory that says drinking a lot ends with hangovers. What we do feel is a strong compulsion to have another drink and to have another drink right now. Not only are we encouraged to drink too much we will also drink at inappropriate times like before important meetings, at work, or on occasions where sobriety is expected. Again, this is because we receive no motivating repulse from doing so. In alcoholics the urge to seek out alcohol is very strong, and the impulse to avoid it is barely, if ever, present. So we are always motivated to drink, and we are never presented with the suggestion that we shouldn’t. We even drink in ways that are contradictory to our own standards of sensible behaviour, and we do this because in the moment our mind always tells us that “drinking is good”; it never tells us to stop. For example, we will drink before driving and picking up children. We know this is an extremely dangerous and foolish thing to do, and we would condemn this behaviour in others. But in the time that precedes picking up the children our minds present no objection to drinking. In fact the opposite happens; our minds still encourage us to seek out and secure drink without consideration of what we are going to do later. We are rewarded with a large dopamine surge on taking that first drink and once we have begun drinking then our brain never says “stop, that’s enough!” but instead insists “there’s time for one more”.
Our problem with alcohol begins and escalates in the reward system in this sequence:-
We drink alcohol which causes the brain to release dopamine. This makes us enjoy the experience of drinking and a trigger is formed. We create another trigger every time we drink under new circumstances. When we encounter the circumstances of the trigger then a craving is launched to encourage us to drink. Triggers strengthen every time we drink in response to the craving they launch making the next craving to come from that trigger more powerful. We continue to crave alcohol for as long we remain somewhere where alcohol is available. The dopamine reward we get on taking a drink in response to a craving also enhances fixation of the memory that this experience was good. The stronger the trigger has become then the more strongly this memory is reinforced. But we do not often form balancing alcohol-avoiding triggers, nor do we often form strong memories of occasions of when drinking was unpleasant, damaging or dangerous. In the absence of triggers and memories that encourage abstinence or moderation we drink more, and we drink more often. As we drink over an extended period the number of drinking triggers we have increases further, and so does their power. Over time the need to drink grows without limit until it is both incessant and compelling while the triggers to avoid drink are progressively weakened. Eventually the need to drink overwhelms all other motivations and desires.
This is the process by which our addiction forms, but we are completely unaware that this is happening to us. All of the changes described here occur in the reward system, and that is a part of the brain that we can’t see into; we have no awareness at all of what is going on in there. We don’t know when triggers form or when they are activated and we have no idea of the strength they have gained. Our only awareness is of a sudden wordless yet urgent demand to drink, though we have no direct knowledge of why we are experiencing this.
The power of the reward system to direct behaviour cannot be over-stated. Humans stand apart from the rest of the animal realm because of our higher mental functions. Humans have a highly developed sense of self, a remarkable ability to discover and invent solutions to problems, logical thinking, and judgement: the means to weigh the pro’s and con’s of any situation. But these functions require relevant information to be found, compared, chosen and then brought into our awareness as concepts, images, ideas and words for us to consider. This requires a huge computational effort, but the reward system requires none of this and it operates up to a million times faster than our conscious thinking. This means that the reward system motivates us to do something long before our conscious mind has even worked out that there’s anything to respond to. For example, we will have jumped back in shock before we are consciously aware of a snake crawling through the grass. We react through our reward system and we respond through our conscious thinking but reaction always comes before a considered response. When a drinking trigger is fired we feel a craving before we are even consciously aware that alcohol may be near. We are quite literally directed to have a drink before we’ve even thought about it. The reward system is enormously compelling, that is its entire purpose, and for most animals it is the sole mechanism that drives their behaviour. A bird does not stop and ponder what it will have for lunch or where; it lacks that ability, yet it feeds successfully throughout its life. The vast majority of all animals’ behaviour is directed exclusively by their reward system. But there are two characteristics in particular that can tip it into a runaway condition. They are; greatly favouring the benefit of something over its disadvantages, and greatly favouring something now over something later. People having both of these characteristics are susceptible to addiction, and these characteristics are very familiar to us; we want more, and we want more now. This is quite literally written into our DNA. In us the reward system becomes destructively associated with the acquisition of alcohol, but we don’t know this has happened. We also have no idea that over a period of time the forces invoked by the reward system have become incredibly powerful. Our behaviour becomes driven by feelings that are involuntary, insistent and beyond our direct control, and they come before considered thought. They come first, we can’t ignore them, we can’t turn them off and we can’t negotiate with them. They are impervious to reason and both defy and precede logic. These are the forces that drive our addiction; they are primal, compelling and unrelenting.
The person approaching alcoholism is aware of none of the changes in their brain in relation to finding and consuming alcohol; to us everything about our drinking seems normal… everything except the way that others are starting to talk about it. As our addiction strengthens we sense no change in ourselves but perceive the problem to be “in the eye of the beholder”. This is the truth for us as we genuinely perceive no problem; our brain insists that “alcohol is good!” despite what other people tell us. The onlooker watching someone become steadily more and more regularly drunk sees a problem, but we see none. This is caused by the different perceptions. The onlooker is seeing us from an un-tainted viewpoint; their memories and triggers associated with alcohol are balanced. To them too much alcohol is bad. But to us, alcohol is good, and more alcohol is also good… and we are completely baffled as to why other people don’t see it the same way.