How Does Neuroscience Explain the Causes of Anxiety?

Note: This article is by Scott H. Young, who explains the neuroscience of anxiety, providing a summary of his readings in this field.

I read Anxious by New York University neuroscientist Joseph LeDoux, an expert in many of the neural processes behind fear and anxiety. In his book, he offers fascinating insights into the mechanisms that give rise to unhappiness.

However, reading this book was not easy at all. It contained several parts on deciphering neural circuit diagrams to try and follow the numerous acronyms that represent incredibly specific brain locations. In an effort to better understand the nature of anxiety and to assist others who may be struggling with it, I compiled a summary of some of the book's key concepts into this post.

Fear and Awareness

Much of the book's opening is devoted to what, at first glance, appears to be a somewhat abstract problem. Do the brain regions that light up when we witness a behavior that we dread actually generate fear?

If you've followed any articles on neuroscience, you may have heard that the amygdala, the almond-shaped part of the brain located under the cortex, is the "fear center."

If you scare a person or a lab rat, for example, the amygdala becomes active.

This has led to a flurry of reports focusing on our feelings of fear within this tiny node of brain tissue, which is unfortunate, LeDoux estimates, because it's never clear if the signals processed by the amygdala are conscious at all.

Instead, he prefers the term "circle of survival." While it is clear that the amygdala is responsible for responding to danger, it is not clear if the activity here directly generates conscious feelings. It is possible that fear is generated as an experience elsewhere, perhaps in the higher cortical regions of the brain responsible for attention, thinking, imagining our future, and remembering our past.

In other words, if a threat occurs in the amygdala without you feeling it, does that make it really fearful? For neuroscientist LeDoux, anxiety that you don't consciously experience isn't anxiety at all.

Side note: Fear, anxiety, and stress have different technical meanings; Fear is the feeling associated with imminent danger, anxiety is the feeling of uncertain threat, and stress is an anxious and repetitive thought.

Adaptive Subconscious and Fear

This distinction between an unconscious survival cycle and a conscious experience is reflected in more than just anxiety. Psychologist Timothy Wilson argues in Strangers to Ourselves that much of our mental processes occur outside of conscious thought.

This new picture of the unconscious, which psychologist Wilson calls the “adaptive unconscious,” is much more mundane. The adaptive subconscious manages life matters, often unknowingly directing our behavior.

The classic reasoning of the adaptive unconscious is preparatory experience. If you glimpse an image and it flashes quickly as a kind of subtle stimulus, the person won't be able to consciously report what they've seen. You can tell, for when they are asked to describe the truth of what they have seen, the best they can do is guess.

But if that image is of a scary face, it will activate subconscious threat circuits, and although you may not be able to notice any difference in conscious observation, you can measure behavioral responses, such as the movement of facial muscles.

Experiments like this indicate that a large part of complex mental processing does not only take place outside our daily awareness; it is completely inaccessible to our conscious mind.

Where Do Feelings of Anxiety Arise from?

If threat circuits are not directly conscious, how do they affect our sense of conscious anxiety? In this case, it is possible that, although threat circuits may not lead to conscious experiences per se, they may lead to other mental processes that make us anxious.

One suggested method was physical response: you feel a little frightened, the amygdala and related areas react quickly, and your heart rate increases. You feel your heart beating fast, and your brain interprets this as fear.

While the somatic feedback loop is a popular theory, LeDoux doubts it can provide a complete explanation for the condition; it may be too slow for this feedback to be the main pathway by which the danger circuit turns into conscious feelings.

Alternatively, the amygdala may evoke patterns in the upper cortical regions of the brain that we consciously sense as fear, in which case the emotions we experience as anxiety are a danger circuit effect that we don't directly experience.

However, danger circuits and feelings of fear are not completely connected, and as we discussed earlier, it is possible to moderately activate the danger circuit without conscious awareness even though the behavioral response is observable. Conversely, it is also possible to feel anxious, even if the threat response circuits are absolutely affected.

The pervasive sense of panic and persistent fear that characterizes much of the anxiety may not need triggering the danger circles to be effective; it may just be a higher mental phenomenon, and as a result, intervention to narrow the danger circles may not help much in these cases.

Threat Circuits and Anti-Anxiety Drugs

This bifurcation of systems—the unconscious threat response system and the conscious fear sensing system—may have implications for our ability to treat anxiety. LeDoux notes, for example, that pharmaceutical companies have not been very successful in discovering anti-anxiety drugs, and if there is something that helps treat anxiety, it is often discovered by chance, not planning.

The distinction between conscious danger and fear circuits may partly explain why drugs are often chosen based on their ability to reduce fear-like behavior in lab animals, but to do so, they may act on unconscious circuits instead of conscious ones. This may not be of much help when the goal is to treat conscious feelings of anxiety.

Exposure Therapy

This perspective may also have implications for the development of therapy. Exposure therapy is somewhat successful in combating anxiety. It works by exposing the patient to the subject of their fear. When they experience fear but nothing happens to them, the next time the fear is felt, it will be lighter, and LeDoux notes that about 70% of patients benefit from exposure therapy.

But this success is not perfect. Spontaneous resuscitation may occur, in which a previously suppressed fear comes back for no apparent reason, and stress or trauma may also trigger relapses.

One reason for this seems to be that the memory of danger and the memory of safety are, in fact, two independent neural circuits. When you recognize the danger at first and then turn off the danger circuit later with exposure, it does not erase the original memory; rather, it creates a second memory designed to suppress the first one, as if instead of erasing the frightening image, you just painted it with a fresh coat of paint, which might later get scratched by accident.

Interestingly, this memory of safety, which suppresses the original response to danger, may be more sensitive to the surrounding environment than the circle of danger itself, and if you learn how to avoid panic at social events when you are with your friend, you may feel that way when that person is not around to accompany you. Reducing the sensitivity of this surrounding environment requires different and repeated exposure in different situations.

Side note: Environmental privacy appears in another context, learning, and in my book UltraLearning, I review research that shows how the things we learn tend to be more visible and more environmentally dependent than we might expect. The appearance of this in different contexts suggests that it's kind of a general principle of how our brain works.

Why Do We Get Stuck in a Spiral of Anxiety?

Anxiety can be self-reinforcing. For example, let's say you get terrified of speaking in front of an audience; you have a speech coming up; you start getting more upset about it, and eventually you come up with an excuse to walk away from it; you feel better now; whatever you were worried about is no longer there.

This actually leads to a pattern of negative reinforcement. By getting rid of the unpleasant thing—your tense feelings—you reinforce the behavior that caused it, and since it is impossible for what you fear to happen, the pattern of avoiding what you fear grows stronger each time you feel anxious.

This may work quite well in nature to a certain extent, for a hare who is almost feasting by a pond may never come back, and it may produce a feeling of thirst, but that is better than being eaten by a crocodile.

The problem is that the avoidance can be very good. The situation you are afraid of may actually be safe, but by avoiding it, you will not face the fact that you do not have to be afraid. In some cases, the avoidance itself becomes worse than the thing you fear by taking costly steps constantly to avoid the situations you are afraid of.

Exposure therapy disrupts this feedback loop. When you expose yourself to the thing you fear and it doesn't produce devastating consequences, you dampen the fear response the next time. So repeat this in the hope that the fear you feel will eventually be mild and not life-threatening.

While this is easy to understand in terms of phobias, you likely have a similar reinforcement mechanism to avoid that feeling, which underlies much of the general panic and anxiety. Most catastrophic fears never really exist, and I have succeeded in avoiding them. Hence, I reinforced the anxious behavior.

Getting Rid of Fears and Modifying Beliefs

Modern exposure therapy is usually based on more than just direct exposure. It also includes cognitive therapy, which involves talking about your fears. The hope here is to clarify some of your beliefs so you can begin to ask questions about them. A person with claustrophobia may worry that if they fail miserably on the podium, their boss will fire them. This may not be realistic, but unless it is clarified, it is very difficult to assess this thinking pattern.

According to Ledoux, these two different traits act on the two disparate systems that contribute to anxiety. Exposure targets the response cycle of danger, a largely unconscious response. So just change someone's beliefs without compromising the cycles of danger, and that person may remain anxious even though they know it doesn't make any sense at all.

You might, for example, "know" that standing in a glass elevator is perfectly safe, but you'd be horrified if you looked over the edge. Likewise, if you just cancel the danger circuit, higher-order cognitive systems may reactivate later. You might hear about a plane crash, and suddenly your fears about flying pop up in ways you can't control.

Reflections on Anxiety and Other Thoughts

The existence of simultaneous conscious and unconscious states and, in fact, treating the two as somewhat separate and contributing systems of behavior is an interesting idea that I take away from the book.

In my private life, I often find myself talking about my problems, either alone or with others, and this process can sometimes help. Writing down my plans, fears, goals, and problems in a journal or discussing them with a friend often leads to new insights or uncovering flaws in the way I think, leading to amazing discoveries.

In other cases, overthinking is exactly my problem; a little thinking leads to more of it, which doesn't work, especially in cases where I feel anxious, where thinking becomes an obsessive-compulsive disorder that is difficult to control.

This book suggests that neglecting unconscious processing may be a major weakness here, and since many mental processes occur in the unconscious, they cannot be treated by overthinking them, and alternative methods such as exposure may be more effective in these cases because they work to solve the problem directly.

This book also mimics another neuroscience book I reviewed earlier, The Hungry Brain, by Stephan J. Guyenet. In this book, sophisticated circuits control how much we eat, which could explain why dieting is so difficult. Like anxiety, these processes happen without our awareness, but they seem to have an amazing effect on our lives.

In conclusion

In some ways, the presence of these invisible processes makes things more difficult, so how do you make decisions when many of your actions are decided by processes that you can't see?

How can you make a difference in your life when the reasons for your behavior are often invisible? How do you define yourself when not much of it is available for self-reflection?

These questions are not at all easy to answer, but I hope that by looking at these ideas, we can uncover new tools for managing anxiety.