What is the single most important personality trait associated with anxiety and depression? Without a doubt, the answer is Trait Neuroticism (TN). As such, it is crucial for people with depression and anxiety to understand this psychological construct. This blog explains what traits are and why TN can be understood as “the sensitivity and activity of the negative affect system”. With this frame we can then explain why people high in TN are vulnerable to developing disorders of depression and anxiety, especially if they are exposed to stressful living conditions and do not have good capacities for processing their emotions in a secure, affirming relational environment.


Defining Personality Traits

Personality traits are one aspect of human personality (see here for a Character Wheel that maps the various domains of human personality). They refer to broad dispositional ways of thinking, feeling and acting that show reliable individual differences across situations. Although there is some debate about the form and number of traits, the most common approach to traits is to divide them into the Big Five domains of Neuroticism, Extraversion, Agreeableness, Conscientiousness and Openness (these can be arranged into the mnemonic OCEAN). There is also some debate about what exactly these traits represent. Part of the reason there is debate stems from how the traits were discovered. The original traits were identified by what is known as the lexical hypothesis, which was an empirical approach that studied how people rated the similarity of adjectives in the dictionary and examined how they clustered together. The earliest trait researchers studied thousands of words that people used to describe people and then saw which ones were correlated. Many researchers found a solid “five factor” solution to how words were correlated across different languages, and this was the beginning of modern trait theory.


Empirically examining how adjectives cluster together is quite different than having a theory of human nature that explains why we have the traits that we do. That is why traits have to be placed into a theory of human nature to fully understand them. We will be focusing primarily on TN in this blog, and will also briefly touch on Extraversion. Thankfully, we can develop a functional understanding these two traits in a very straight forward way with Behavioral Investment Theory.
The essence of BIT is the proposition that the brain is the organ of behavior, and the fundamental problems of animal behavior can be divided into two large domains: 1) the problem of avoiding the bad (which can be defined as that which was negatively correlated with survival and reproductive success), and 2) approaching the good (that which was positively correlated with survival and reproductive success).


Given this division, it makes perfect sense that there would be a negative emotional system (that emerges out of pain) and a positive emotional system (that emerges out of pleasure).The former is nature’s way of getting animals to avoid the bad, and the latter orients animals to invest in the good. By putting the empirical findings of the lexical hypothesis into the theoretical formulation provided by BIT, we now have a clear functional framework for understanding TN. Vertebrate animals have a “negative affect system” that orients them to avoid negative/punishing situations, and TN refers to the individual differences among animals in the sensitivity and activity of this system. In addition, vertebrate animals have a “positive affect system” that orients them to approach positive/rewarding situations, and trait extraversion refers to individual differences in their energy, engagement and sociability. Consistent with this formulation, animals like dogs are as readily and reliably identified on these two traits as people are. With TN placed into this functional theory of the mind, we are now in a place to understand its parts and to be clear about the crucial role it plays in developing anxious and depressive disordered states.
The Key Components that go into Trait Neuroticism

According to the unified approach, there are four core affective poles that together constitute the negative affect system. Two are primary, and two are social in nature. The two primary affective poles are, in terms of function, “active avoidance of negative future” and “shutdown from loss and frustrative nonreward”. These are the technical, functional descriptions that line up with NIMH’s Research Domain Criteria (RDoC). You likely would recognize them by the more common terms of anxiety/fear and sadness/depression. Fear and anxiety energize the animal to actively invest in avoiding bad outcomes, which is why there is (a) acute physiological arousal; (b) a feeling of distress and vigilance, and (c) cognitive worry (thinking a bad thing is going to happen). Sadness and depressive demoralization are feelings states that focus on the past and are about internalizing loss and poor or ineffective investment, which is why the energy system shuts down (to regroup until the hopeless/powerlessness subsides).


There are also two social poles of negative affect, one directed toward the self (guilt and shame) and the other directed toward punishing others (anger and hostility). Shame is activated in response to defeat and feelings of inferiority, guilt orients us to diminish our selfish tendencies and make amends. Anger orients us to defend our interests when we are not treated fairly (see here for a wonderful display of anger regarding fairness in a monkey), and hostility is about punishing others who we perceived to be defined against our interests.    
I think it is helpful to see this formulation of high TN by referencing it to the Influence Matrix. Readers of this blog will know that the Influence Matrix is map of the human relationship system. Although it is beyond the scope of this blog, this shows the clear connection between our social needs for relational value and our feeling states.


Clarifying what it means to be high in Trait Neuroticism


To understand what it means to be high in TN, let’s begin with an example of someone with incredibly low TN. He was an individual I worked with who I characterized as a “friendly psychopath” who just did what he wanted to do for the fun of it. Consider the following narrative that brought him into the corrections institute where I was working with him. At 19, he hooked up with a willing 12 year old and started having sex with her in her basement. Her father came down stairs screamed at him and went to get his gun. He raced out of there, on the way, stealing their car to drive away. Well, soon the cops were on his trail and he was racing away from them. Finally, the car spun out and he crashed into a pole. Not wearing his seatbelt, his forehead hit the dashboard, cracking it open (you could still see the faint scar several years later). He recalled looking in the mirror, seeing the flap of his forehead hanging down with all the blood, seeing the cop cars flashing lights as they approached the car with guns drawn. His thought was: “Cool”.


Notice, in addition to his lack of morality and concern for others, is a complete lack of fear and anxiety. He simply did not get the jolt of avoidance that any normal person would. He did not worry about sleeping with a 12 year old with her parents’ home, or stealing the car, or crashing it, or cracking his head open, or even having guns pointed at him, with the inevitable consequence of going to jail. When we consider the contrast of this example and a college student who is freaking out because she might get a C on a test, we can get a clearer sense of how much individuals can vary in this trait.


In addition to the four affective poles that contribute to TN, I also like to think about TN in terms of a “wave function”, which involves the components of sensitivity, frequency, intensity, and duration (see Figure 2). Sensitivity refers to the ease with which the negative affect system is triggered. The greater the sensitivity, the lower the stressor or problem needs to be to get the system going.

Frequency refers to how often the system is activated. This, of course, will relate to how well or not the individual is harmonized with their environment and regularity of the pattern of stressors.

Intensity refers to how strong the negative affect response is. Is the person bummed or devastated? A bit nervous or completely panicked? Irritated or filled with rage? Finally, duration refers to how long the system is activated, and how difficult it is to sooth and return to baseline.
If you are high in TN, it means that you are: 1) sensitive to stressors; 2) you are likely to have more frequent activations of negative emotions; 3) your reactions are more likely to be intense; and 4) they will last longer and it will take longer to return to baseline.

  
Why TN Leads to Depressive and Anxious Disorders
Given the very close association between anxiety and depression and the understanding of high TN offered here, it is clear that high TN should be related to anxiety and depressive disorders. And, empirically, the relationship is very strong. However, people who are high in TN are not destined to develop disorders of anxiety and depression. TN makes you vulnerable, but there are other ingredients that are needed.
Depressive and anxiety disorders are maladaptive patterns of negative emotion that arise out of vicious cycles.There a vicious cycles that emerge with the environment (both social and nonsocial), and there are intrapsychic vicious cycles. Depressive and anxiety disorders are usually combinations of both. A classic vicious environmental cycle that gives rise to depressive disorders occurs when a person feels frustrated and down and starts to do less and less (i.e., stay home, drink, watch TV). Although shutting down in a natural response, if the shutdown leads to greater and greater levels of disengagement (which it tends to do in this culture), then a vicious cycle emerges, where the shutdown leads to less avenues of mastery and pleasure and this leads to greater discouragement and more shutdown.


There are also intrapsychic vicious cycles that give rise to depressive and anxiety disorders. It is no accident that depressive and anxiety disorders tend to emerge during adolescence. What is the key development in adolescence? The development of an identity and self-concept that starts to play an increasingly active role in reflecting on and evaluating the self. Although younger kids definitely have a sense of self, it is much less developed. The adolescent is capable of asking, “Who am I versus who I ought to be?” “What is my ideal self?” “How should I feel?”
Now imagine the emergence of this budding self-concept system in the context of the turmoil of puberty and the fact that one’s friends are going through the same process. If one is exposed to significant stress and do not have a solid relational system to process negative feelings, then it is very likely that the internal narrator will become stressed in general and stressed with one’s self in particular. That is, the adolescent who is high in TN will not only feel more stress, but they will wonder why they tend to “freak out” or why they are so sensitive and they are very vulnerable to developing an inner critic.


So the internal critic starts to criticize the self, which in turn sends very distressing information to the core emotional system. Images of defeat, shame, ineffectiveness drive negative feelings. I call this “closing the loop” and it is one of the key elements that gives rise to depression and generalized anxiety. The loop is the disruptive feedback between the negative affect system and the critic. Not only does the adolescent feel more negative than average (by definition with high TN), but if they develop an inner critic which blames them and attacks them for their feelings, their feeling system will be chronically activated by this voice, and the critic will be chronically frustrated by the negative feelings. It is this loop between feelings and narrator that plays a key role in so many depressive and anxiety disorders and it is the primary reason they arise during adolescence. (See here for a blog on the internal critic and how to CALM it).


Conclusion

I have worked with lots of folks with anxiety and depressive disorders. Many of them, of course, had therapy in the past. However, very few of them (I can only recall one person) received a clear formulation of high TN in the context of their treatment. This is unfortunate because high TN provides a clear way for many folks to understand what it is about their structure that makes them vulnerable to strong negative reactions and, if they don’t handle those negative reactions well, then disordered states arise. This insight often allows them to be a bit more accepting of their feelings, at least intellectually. And it sets the stage for them to understand why they need to be quite systematic in the way they learn to process their feelings (see here for how we need to understand emotions and adaptively process them).