Understanding Psychological Disorders
How clinicians define, model, and classify psychological disorders using the biopsychosocial approach and the DSM.
A psychological disorder is a characteristic set of thoughts, feelings, or actions that causes noticeable distress to the person experiencing it, causes maladaptive functioning in society, or is considered deviant by that person's culture. Clinicians approach these disorders through two major models — biomedical and biopsychosocial — and classify them using a shared diagnostic reference, the DSM.
Key Takeaways
A psychological disorder is defined by meeting any one of three criteria: distress, maladaptive functioning, or cultural deviance.
The biomedical approach treats disorders as rooted in a biomedical disturbance and focuses on symptom reduction, but ignores lifestyle and socioeconomic status — it's most effective when paired with a broader approach.
The biopsychosocial approach (George Engel, 1977) considers biological (something in the body), psychological (the individual's own thoughts/emotions/behaviors), and social (the individual's surroundings) components together, aiming to provide both direct therapy (medication, psychologist meetings) and indirect therapy (educating and empowering the patient's family and friends).
The DSM (Diagnostic and Statistical Manual of Mental Disorders), published by the American Psychiatric Association (currently DSM-5-TR), is a symptom-based diagnostic classification tool used to help clinicians diagnose and consider the biopsychosocial factors behind a patient's disorder.
What Counts as a Psychological Disorder
A psychological disorder is defined by any one of three criteria:
Distress: the thoughts, feelings, or actions cause noticeable distress to the person experiencing them.
Maladaptive functioning: they cause the person to function poorly, or maladaptively, in society.
Cultural deviance: they're considered deviant by the individual's own culture.
A pattern of thoughts, feelings, or actions doesn't need to meet all three criteria to be considered a disorder — meeting any one of them is enough.
The Biomedical Approach
The biomedical approach treats psychological disorders through interventions centered on symptom reduction. It assumes that all disorders have their roots in a biomedical disturbance.
This approach fails to take into account a person's lifestyle and socioeconomic status. It's most effective when supplemented with a broader approach to diagnosis and treatment, rather than used on its own.
The Biopsychosocial Approach
The biopsychosocial approach, introduced by physician George Engel in 1977 as a contrast to the purely biomedical model, assumes that biological, psychological, and social components all contribute to an individual's disorder.
MCAT Callout — Telling the three components apart: the biological component is something in the body, like a genetic syndrome. The psychological component stems from the individual's own thoughts, emotions, or behaviors. The social component results from the individual's surroundings — things like class discrimination or stigmatization. A vignette that mentions a patient's genetics is pointing to the biological component; one that mentions the patient's own coping thoughts is psychological; one that mentions how others treat the patient is social.
All three of these components are considered together under the biopsychosocial approach. Its goal is to provide two kinds of therapy:
Direct therapy: medication or periodic meetings with a psychologist, aimed at the patient.
Indirect therapy: aims to increase the patient's social support by educating and empowering their family and friends.
Classifying Psychological Disorders: The DSM
Psychological disorders are classified using the Diagnostic and Statistical Manual of Mental Disorders (DSM), published by the American Psychiatric Association — currently in its fifth edition, text revision (DSM-5-TR), released in 2022. The DSM was created to help clinicians consider all of the factors above when diagnosing a patient, and it's used as a diagnostic tool with statistical data in the United States.
The DSM is a compilation of many known psychological disorders. It works by description of symptoms: physicians match a patient's compiled list of symptoms against the categories in the DSM to arrive at a diagnosis.
Why Understanding Psychological Disorders Matters for the MCAT
Questions on this material tend to test whether a reader can correctly apply the underlying framework to a described scenario, rather than recall isolated facts:
Any one criterion is sufficient. A vignette only needs to show distress, maladaptive functioning, or cultural deviance to describe a disorder — not all three at once.
Biomedical isn't wrong, just incomplete. The biomedical approach is a valid starting point, but the MCAT is likely to test its limitation (ignoring lifestyle and socioeconomic status) rather than its validity.
Matching a described factor to biological, psychological, or social. This is the most common trap — a passage describing genetics, a patient's own thought patterns, or a patient's social environment is pointing to a specific one of the three biopsychosocial components.
Direct vs. indirect therapy. Direct therapy targets the patient directly (medication, therapy sessions); indirect therapy targets the patient's support network.
The DSM is a classification tool, not a treatment manual. It organizes disorders by symptom description for diagnosis — it doesn't itself prescribe treatment.
Common MCAT Mistakes
Assuming a disorder must meet all three criteria (distress, maladaptive functioning, cultural deviance) at once, rather than recognizing that any single one is sufficient.
Dismissing the biomedical approach as simply wrong, rather than recognizing it as valid but incomplete — its main limitation is ignoring lifestyle and socioeconomic status, not that symptom-focused treatment never helps.
Misidentifying which biopsychosocial component a vignette detail points to — mixing up a patient's own coping thoughts (psychological) with how others around them behave (social), or missing a biological detail like a genetic syndrome.
Treating the DSM as a treatment manual, rather than a symptom-based diagnostic classification tool that helps clinicians reach a diagnosis.
MCAT-Style Concept Check
Question: A patient recently diagnosed with a mood disorder reports that several coworkers have started avoiding him and gossiping about his diagnosis, which has made his symptoms worse. Under the biopsychosocial approach, which component does this detail describe?
A) Biological
B) Psychological
C) Social
D) Biomedical
Answer: C
Explanation: The coworkers' avoidance and gossip describe the patient's surroundings — stigmatization from others — which is the social component. The biological component would involve something in the patient's body, like a genetic or physiological factor. The psychological component would involve the patient's own thoughts, emotions, or behaviors, not other people's treatment of him. "Biomedical" (D) isn't one of the three biopsychosocial components — it's a separate, competing model of disorder.
FAQ
What are the three criteria for a psychological disorder?
Distress, maladaptive functioning, and cultural deviance. A pattern of thoughts, feelings, or actions only needs to meet one of these three criteria to be considered a disorder — not all three.
What's the difference between the biomedical and biopsychosocial approaches?
The biomedical approach treats disorders as rooted purely in a biomedical disturbance and focuses on symptom reduction, ignoring lifestyle and socioeconomic status. The biopsychosocial approach, introduced by George Engel in 1977, considers biological, psychological, and social components together.
What counts as the biological, psychological, and social components of a disorder?
The biological component is something in the body, like a genetic syndrome. The psychological component is the individual's own thoughts, emotions, or behaviors. The social component is the individual's surroundings, such as class discrimination or stigmatization.
What is the DSM and who publishes it?
The DSM (Diagnostic and Statistical Manual of Mental Disorders) is a symptom-based diagnostic classification tool published by the American Psychiatric Association, currently in its DSM-5-TR edition. Clinicians match a patient's symptoms against DSM categories to reach a diagnosis.
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