The science of classifying disease is nosology, an odd name for a basic part of medicine. Common approaches include grouping by the major organ affected, the cause, various biomarkers, and more. These aren’t exclusive; viral encephalitis is an infectious neurological condition with particular findings in cerebrospinal fluid. In fact, the better we understand a disease, the more ways we can slice it.
But we don’t understand mental illness, and our nosology reflects this. Psychiatry defines disorders with symptoms and a few signs, then stacks them according to some presumed similarity. For instance, generalized anxiety, panic disorder, and specific phobias are all anxiety disorders, there’s a nebulous idea of personality with its ten dysfunctions, and eating disorders get their own section. But most common conditions are heterogeneous, and the categories we force on top - depressive disorder, trauma disorder, personality disorder - add little value. Comorbidity across groups is just as likely as within them.
One problem is that, in counting up symptoms, we downplay their context. This is bad because we’re dealing with emotional disorders, and emotions evolved to address specific situations. In fact, if you listen to what patients say, it’s hard not to pick up on certain themes. We could make use of this aboutness. We already do, to an extent. Delusional disorder has five subtypes based on the content of the delusion. Social anxiety and illness anxiety are their own diagnoses, not lumped with generic anxiety, and we could partition other conditions in the same way. Here’s what I mean.
Lunches, brunches, interviews by the pool
Many mental illnesses are about social status, an important value for almost everyone. The obvious is social anxiety, in which people fret about losing status by doing something humiliating. In addition, there’s a good case for social rank depression due to a perceived loss. The theory proposes that
low mood and submissive behaviour are involuntary yielding responses to defeating competitive situations (i.e., in the competition for resources, such as for food or mates, with dominant others), and these responses are as a means of inhibiting an aggressive ‘comeback’, communicating a ‘no threat’ status and facilitating acceptance of the situation. This is reflected in the submissiveness, withdrawal and self-criticism that are indicative of depression states.
So social anxiety is about the risk of losing status, while depression sets in after the fact.
Some people’s entire worldview revolves around social rank. When fear of humiliation, social withdrawal, and self-criticism are pervasive, we call it avoidant personality. It’s lifelong social anxiety and depression, as if the person’s “status-o-meter” is forever stuck on the lowest setting. At the other extreme is narcissistic personality. I bet you can think of an example. The criteria include things like believing they “can only be understood by or associated with other high-status people” and “demanding excessive admiration.” A narcissist’s status-o-meter is way too high, and bad behaviors ensue.
Psychosis incorporates status too. One flavor of mania involves delusions about knowing or being the president, Bill Gates, Elon Musk, Buddha, Jesus, etc. Grandiosity also shows up in delusional disorder, in which people have delusions in just one area. I knew an otherwise rational guy who claimed to be a physician, attorney, combat medic, and freelance FBI investigator. The existence of discrete delusions hints at some modularity in the brain.
Getting Things Done
Mood is the body’s mechanism for accomplishing tasks, whether it’s foraging mushrooms, hunting a bison, working a field, writing a term paper, or doing the laundry. Excitement, motivation, and focus emanate from this system, which can get stuck in low or high gear. Apathetic depression feels flat, unfocused, and listless. I just lay on the couch all day, I can’t get anything done. This differs from sadness and guilt. At the other end, manic people explode with energy, work for days on end with zero second-guessing, and fly unbounded into psychosis.
Even serviceable mood systems may not be robust. Task anxiety, now subsumed under GAD, is preemptive worry about doing things. What if I’m late to the appointment? What if I can’t finish my paper on time? What if I get a B in Biochem and don’t get into medical school and have to work at McKinsey? The worry all revolves around productivity and performance, in a form of internally generated noise. ADHD mirrors this, as patients fail to complete tasks due to external noise - distractions - instead. Completion OCD, with its checking and ordering and just righting behaviors, is a malfunction in which you’re never quite sure that a task is done.
Fear is the mind-killer
Avoiding death and dismemberment is important, and false alarms are the cost of doing business. This covers a lot of ground. Harm anxiety, now part of generalized anxiety, is about the possibility of random bad things: my kid could get hit by a car, my spouse could get fired, we could all die in an earthquake. These fears are lightly held but omnipresent. Others are more enduring, like specific phobias of spiders, dogs, crowds, blood, and so forth. Exteroceptive panic attacks may result from an immediate threat, real or imagined. Harm OCD goes here as well, while classic PTSD is just a basic fear disorder incited by a particular event.
Fear can be delusional too. Paranoia shows up in schizophrenia, but also in dementia and delirium, a temporary state of brain failure due to medical illness. Delusional disorder has a persecutory type, with people convinced they’re being followed, harassed, surveilled, or mistreated in various inexplicable ways. We talk about psychosis as a “thought” disorder, but a common thread is just fear, swaying judgment as always.
The Body Done Wrong Again
Big chunks of brain are about the body, scanning and mapping and interpreting away. This leaves a lot of room for neurological misconduct, stirring up the feeling that something is wrong with my body.
For instance, humans display a distinct zone of worry about getting sick, separable from other topics. Every second-year medical student experiences illness anxiety, née hypochondriasis: “What’s that rash? Well great, I have cutaneous T-cell lymphoma.” Excessive vigilance to normal body sensations can also set off the alarm with an interoceptive panic attack.
On similar lines, somatization refers to unpleasant body feelings with no apparent cause. Everybody gets these, but some people are just bombarded by interoceptive noise, which must be very confusing. Functional neurologic disorders are the converse, involving overt deficits like limb weakness, blindness, or garbled speech without a clear reason. Somatic depression, now known as fibromyalgia, chronic fatigue, or myalgic encephalomyelitis, is probably the brain stuck in sickness behavior mode.
Other conditions fall under this theme. Dissociation is detachment from the body, as if the scanner went offline. Classic contamination OCD can appear without other OCD themes like harm or sacrilege. What about body dysmorphia? An overwhelming preoccupation with a perceived bodily flaw fits right in. When an irrational idea becomes truly fixed, we call it a somatic delusion, like people distressed about the insects infesting their skin or the implant in their abdomen.
Managing Closeness
Attachment refers to close relationships between animals, starting with parent-child and extending to adult interactions. Attachment theory describes emergent patterns such as secure, avoidant, anxious, and disorganized. This theory is well-developed, accepted by almost everybody, and relevant to both daily life and therapy. Despite this, the DSM 5 mentions it only in relation to childhood conditions like separation anxiety and reactive attachment disorder, reserved for children raised in distressing circumstances.
What about adults? Emotional distress and dysfunction often stem from attachment. Like children, we experience anxiety and separation panic attacks when threatened with the loss of a partner or family member. Relationship OCD involves repeatedly questioning and seeking reassurance about your relationship. A common cause of sadness, low self-worth, and hopelessness is being alone; lonely depression is when you can’t find a partner, and bereavement occurs after you lose one.
The idea of attachment types is convenient, but of course it’s a continuum. People are more or less secure, more or less avoidant, more or less anxious. At the avoidant extreme is schizoid personality, individuals who just don’t want relationships. Think hermits and mountain men who prefer solitude. On the anxious end, people with dependent personality can’t stand being alone, can’t make their own decisions, and can’t help coming across as needy.
Borderline personality has a lot going on, but insecure attachment is a pillar. Key symptoms include “frantic efforts” to avoid abandonment and “chaotic interpersonal relationships.” Rather than an extreme set-point, borderline personality seems to involve high gain, with outsized reactions to routine events. Complex or attachment PTSD is a very similar concept. You could make a case that other symptoms like emotional dysregulation, self-injury, and intense anger emerge from same dynamic.
Attachment can also turn psychotic. People with jealous delusions are convinced their partner is unfaithful. Erotomanic delusions involve the fixed belief that another person is in love with them. It’s more common in women and often involves a high-status or celebrity object. Both may lead to unfortunate outcomes, like stalking or attempting to assassinate Ronald Reagan.
So What
It’s fun trading around diagnoses and symptoms in psychiatric fantasy football, but the point is to better understand mental illness. I realize this all relies on interpretation, and risks overinterpretation. You can’t escape theory-ladenness! Anyway, the world doesn’t need another “atheoretical” symptom factor analysis. Grouping disorders by theme is intuitive and ultimately complementary to schemes based on symptoms or genetics.
One goal is cleaner diagnosis. Social rank depression and apathetic depression and somatic depression should look and feel somewhat different, if they’re different things, and this could inform treatment. There's a little evidence that depression symptom profiles vary by stressor. On the other hand, I’m not convinced that common scales like the PHQ-9 and GAD-7 tell us much more than a distress thermometer. We might also expect these diagnoses to mostly stay within categories. Someone with separation panic may be more prone to relationship OCD and lonely depression, if these themes reflect some underlying brain function.
And this is the more interesting point. Do humans have separable “systems” for seeking resources, avoiding danger, bonding to mates, monitoring our bodies, and striving for status? I think we do! These wouldn’t be anatomic structures, but rather behavioral control systems akin to the multi-organ mechanisms regulating blood pressure, pH, or glucose. As in cardiovascular or endocrine physiology, numerous layers of control interact with each other, and go awry in various ways, producing a vast range of behavior and misbehavior.
Humans are creatures of meaning!! Brilliant argument from dysfunction (but applicable to normal function too, of course).
And, intuitively, should be very well grounded in some sort of neuropsychological reality via the idea (probably the fact) of specific modules that evolved to manage specific behaviours key for successful survival and reproduction.
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On the "introspection of own & acquaintance crazy" side, the distinction between different kinds of "anxiety" or "depression" seem very obvious. Even at my very worst of trauma-prompted crazy fears my mind never went towards any form of social anxiety (my hypothesis is that's because of protective effects of slightly psychopathic lack of concern with social validation) and however listless, useless and unable-to I get, I never feel guilt or self loathing shame for that, etc etc.
"Content" seems to matter, functionally, indeed.
A thoughtful review of some of the main ways we suffer. Thank you. After reading, it strikes me that perhaps we do in fact know quite a lot about mental illness and its causes (which are not to be confused with knowing all the mechanisms—unless one is a reductionist!).