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What are the different mental illnesses out there and how do I know what I have?

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

Bipolar and Related Disorders

Depressive Disorders

Anxiety Disorders

Obsessive-Compulsive and Related Disorders

Trauma- and Stressor-Related Disorders

Dissociative Disorders

Somatic Symptom and Related Disorders

Feeding and Eating Disorders

Elimination Disorders

Sleep-Wake Disorders

Sexual Dysfunctions

Gender Dysphoria

Disruptive, Impulse-Control, and Conduct Disorders

Substance-Related and Addictive Disorders

Neurocognitive Disorders

Personality Disorders

Paraphilic Disorders

Unclassified, medication-induced and conditions that affect mental health disorders

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.



1.. Diagnostic and Statistical Manual of Mental Disorders. DSM Library

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).

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