I would argue that, at least once in our lifetime, we all wonder whether our brains are working properly. Maybe you noticed that lately your mood has been strange for no particular reason, or the way your brain seems to work is quite different from everyone else’s. Persistent and significant changes in behavior, the way one thinks or feels, and one’s physical well-being, are all hints of a possible mental health disorder.
You might ask, how do I know what I have?
While it can be tempting to consult Dr. Google, only clinical assessments can arrive at a clear diagnosis. The reason why becomes clear once we realize that there are hundreds of mental health disorders out there.
Mental health professionals usually consult a book called the Diagnostic and Statistical Manual of Mental Disorders (DSM) to arrive at a diagnosis. Currently, in its 5th edition, the DSM has been in use since 1844. It lists the majority of known mental disorders, including what symptoms are used to diagnose them, as well as their development and course.
But the DSM-5 isn’t the be-all and end-all of a diagnosis. For example, many argue that it turns normal behaviors and emotions like grief into mental health disorders. Moreover, the DSM-5 splits diagnoses into neat, separate boxes, often failing to account for how mental health disorders can co-exist in individuals.
The DSM-5 disorders are organized based on the time they usually begin, starting with early-life (neurodevelopmental, like autism spectrum disorder), followed by adolescence and young adulthood (such as bipolar, depressive, and anxiety disorders), as well as adulthood and later life (neurocognitive disorders, for instance, caused by Alzheimer's Disease).
Within disorders that happen at similar stages of life, the DSM-5 defines what is known as internalizing and externalizing disorders, based on the way the symptoms usually get expressed. Internalizing disorders (anxiety, depression) are marked by behaviors that affect oneself while in externalizing disorders (substance use, disruptive conduct) the negative behaviors are directed toward others and the environment.
Does this mean that everyone can read the DSM-5 and self-diagnose? Not at all.
Mental health professionals do much more than check off a symptom list. In order to weave the threads of a diagnosis, a careful clinical history and summary of social, psychological, and biological factors are needed. Another crucial factor is time. While fluctuations in emotions are expected in life, specific durations of symptoms are essential before a diagnosis. Additionally, because symptoms are often shared across different conditions, only mental health professionals have the expertise to dissect the pool of classes in the DSM-5.

But what are the classes? A summary of their characteristics can be found in the dropdown menu below:
Neurodevelopmental Disorders
Often manifest before the child enters school and are characterized by limitations in personal, social, academic, or occupational activities. Examples: autism spectrum disorder, intellectual developmental disorder and attention-deficit/hyperactivity disorder (ADHD).
Schizophrenia Spectrum and Other Psychotic Disorders
Marked by delusions, hallucinations, disorganized thinking, grossly disorganized or abnormal motor behavior, and negative symptoms, such as reduced emotional expression or lack of pleasure. Examples: delusional disorder, schizophrenia and substance/medication-induced psychotic disorder.
Bipolar and Related Disorders
Characterized by a fluctuation between abnormal and persistent periods of elevated, expansive, energetic, or irritable mood, and bouts of depressive episodes, for example, with severe changes in sleep and eating habits, feelings of worthlessness and fatigue. Examples: bipolar I disorder, bipolar II disorder and substance/medication-induced bipolar and related disorder.
Depressive Disorders
Distinguished by a presence of sad, empty, or irritable mood, affecting an individual’s capacity to feel pleasure, eat and sleep well, and perform in their day-to-day lives. Examples: major depressive disorder, premenstrual dysphoric disorder and substance/medication-induced depressive disorder.
Anxiety Disorders
Marked by excessive and persistent fear and anxiety due to specific or general triggers. These emotions are accompanied by bodily responses, for example, thoughts of immediate danger, increased heart rate, muscle tension, or avoidant behaviors. Examples: phobias, panic disorder and generalized anxiety disorder.
Obsessive-Compulsive and Related Disorders
Characterized by unwanted recurrent and persistent thoughts, urges, preoccupations, or images that drive an individual to perform repetitive and rigid behaviors, which can be body-related, for example, hair pulling. Examples: obsessive-compulsive disorder, body dysmorphic disorder and trichotillomania (Hair-Pulling Disorder).
Trauma- and Stressor-Related Disorders
Disorders in which persistent anxiety, fear, anger and aggressiveness happen in response to a clear traumatic and stressful event. Examples: reactive attachment disorder, posttraumatic stress disorder (PTSD) and prolonged grief disorder.
Dissociative Disorders
Distinguished by a break in an individual’s perception of who they are, their memories, emotions, body representation, and motor control. Examples: dissociative identity disorder, dissociative amnesia (memory loss) and depersonalization/derealization disorder.
Somatic Symptom and Related Disorders
Marked by pervasive distress and impairment due to bodily or somatic symptoms and/or illness anxiety, most commonly present in primary care. Examples: somatic symptom disorder, illness anxiety disorder and functional neurological symptom disorder (conversion disorder).
Feeding and Eating Disorders
Characterized by a persistent disturbance of eating or eating-related behavior, altering consumption or absorption of food, as well as impairing physical and psychological health. Examples: anorexia nervosa, bulimia nervosa and binge-eating disorder.
Elimination Disorders
Usually diagnosed in childhood or during adolescence. These disorders involve the inappropriate elimination of urine or feces. Examples: enuresis and encopresis, or repeated urination or defecation in inappropriate places, respectively.
Sleep-Wake Disorders
Typically involve persistent issues in the quality, timing, and amount of sleep that affect the day-to-day functioning of an individual. Examples: insomnia disorder, obstructive sleep apnea (pause in breathing) hypopnea (shallow breathing) and nightmare disorder.
Sexual Dysfunctions
Characterized by a severe disturbance in a person’s ability to respond sexually or to experience sexual pleasure. Examples: delayed or premature ejaculation, erectile disorder and female orgasmic disorder.
Gender Dysphoria
This class is dedicated to clinically-relevant distress that may accompany the difference between one’s experienced gender and one’s assigned gender at birth. Example: gender dysphoria.
Disruptive, Impulse-Control, and Conduct Disorders
Essentially includes conditions involving problems in self-control of emotions and behaviors, violating the rights of others and societal norms, for example, through aggression or destruction of property. Examples: conduct disorder, antisocial personality disorder, and kleptomania (habits of stealing).
Substance-Related and Addictive Disorders
Marked by intense activation of the brain reward system and deactivation of brain inhibitory mechanisms, severely disrupting an individual’s ability to function in other aspects of life. 10 separate classes of drugs are included, notably alcohol; caffeine; cannabis; hallucinogens; inhalants; opioids; sedatives, hypnotics, or anxiolytics; stimulants; tobacco; and other. Each substance is associated with use, intoxication, withdrawal, and associated mental disorders. Examples: alcohol use disorder, alcohol intoxication, alcohol withdrawal, and alcohol-induced mental disorders.
Neurocognitive Disorders
Characterized by a cognitive dysfunction that is acquired in adulthood. They can occur as a result, for instance, of Alzheimer’s disease, Parkinson’s disease, traumatic brain injury, HIV infection, or Huntington’s disease. Examples: delirium, and syndromes of major or minor neurocognitive disorder.
Personality Disorders
Distinguished by strong and lasting patterns of behavior that start in adolescence or early adulthood and deviate from the norms and expectations of the individual’s culture, leading to significant distress or impairment in life. Examples: general personality disorder, borderline personality disorder and narcissistic personality disorder.
Paraphilic Disorders
Marked by intense and persistent atypical sexual interest that can involve non-human objects, cause distress to the individual, risk harm to others, or is non-consensual. Examples: voyeuristic disorder, sexual masochism disorder and pedophilic disorder.
Unclassified, medication-induced and conditions that affect mental health disorders
Besides the well-known classes outlined above, the DSM-5 also includes mental disorders induced by medication, for instance, medication-induced parkinsonism; unclassified mental disorders; and conditions or environmental problems that can affect an individual’s mental disorder, for example, suicidal behavior and nonsuicidal self-injury. More research is needed to understand how the disorders in these three chapters come to be and their treatments.
Research shows that a diagnosis can be life-changing if it’s done at the right place and time. It can offer validation, relief, and hope for recovery, though for some it can also increase the stigma they feel. Different tools exist for the treatment and management of each mental health disorder. Knowing what goes on inside our own internal worlds is the first step. Seeking a clinical, outside perspective is the second.
Thank you to our curious readers for posing this important question! If you have your own mental health questions, please reach out on Twitter through our website.
Sources:
1.. Diagnostic and Statistical Manual of Mental Disorders. DSM Library https://dsm-psychiatryonline-org.ezproxy.library.uvic.ca/doi/book/10.1176/appi.books.9780890425787.
2. Perkins, A. et al. Experiencing mental health diagnosis: a systematic review of service user, clinician, and carer perspectives across clinical settings. The Lancet Psychiatry 5, 747–764 (2018).
3. Marshall, M. The hidden links between mental disorders. Nature 581, 19–21 (2020).
4. Pescosolido, B. A., Gardner, C. B. & Lubell, K. M. How people get into mental health services: Stories of choice, coercion and “muddling through” from “first-timers”. Social Science & Medicine 46, 275–286 (1998).