AP® Psychology review sheet from Aim for Five (aimforfive.com/psych/units/5/5-3)
Unit 5 · Topic 5.3
5.3 Explaining and Classifying Psychological Disorders
How do psychologists decide when thoughts and behaviors count as a psychological disorder? They weigh dysfunction, distress and deviation from cultural norms, and trained clinicians use systems like the DSM and ICD. This topic also covers the pros and cons of diagnosis and how each psychological perspective, and the models that combine them, explain disorders.
Key terms
- DSM
- ICD
- stigma
- eclectic approach
- biopsychosocial model
- diathesis-stress model
Defining a psychological disorder
A psychological disorder involves significant disturbances in a person's thoughts, emotions or behaviors. Three factors help identify one:
- Dysfunction: the pattern interferes with daily life, such as school, work, relationships or self-care.
- Distress: the person feels significant suffering or discomfort.
- Deviation: the pattern is unusual compared with the norms of the person's culture.
Diagnosis: tools, benefits and risks
None of these factors is enough by itself. Being unusual isn't a disorder (a gifted violinist is unusual), and distress can be a normal response, like grief after a loss. Cultural context matters too: hearing a deceased relative's voice while grieving is expected in some cultures and would be judged differently elsewhere.
Diagnosis requires specialized training and evidence-based tools such as structured interviews. Two main classification systems are used. The American Psychiatric Association publishes the Diagnostic and Statistical Manual of Mental Disorders (DSM), now in its fifth edition, text revision (DSM-5-TR). The World Health Organization publishes the International Classification of Diseases (ICD), now ICD-11, which includes a section on mental disorders. (Some course materials call it the International Classification of Mental Disorders; either way, it's the ICD.) Both are revised as research advances.
Diagnosis has benefits and costs. A diagnosis can give a person a name for what they're experiencing, guide effective treatment, allow insurance coverage, and help researchers study a condition. But labels can also bring stigma, unfair negative judgments that lead to shame, discrimination or avoiding treatment. Diagnosis can also be affected by bias, including racism, sexism and ageism. Using person-first language, such as 'a person with schizophrenia' instead of 'a schizophrenic,' is one way to remember that a diagnosis describes a condition, not a whole person.
You should never diagnose real people, including yourself or friends. On the exam, you'll match symptoms described in fictional scenarios to concepts.
How each perspective explains disorders
| Perspective | Proposed cause | Example: a person with intense fear of dogs |
|---|---|---|
| Biological | Genes, brain structure or neurotransmitter differences | An inherited tendency toward an overactive amygdala |
| Psychodynamic | Unconscious conflicts, often from childhood experiences | Unresolved anxiety from early life displaced onto dogs |
| Behavioral | Maladaptive learned associations and reinforcement | Being bitten as a child (classical conditioning), with avoidance reinforced by relief |
| Cognitive | Maladaptive thoughts and beliefs | Believing 'every dog will attack me' |
| Humanistic | Not enough acceptance and support, which blocks personal growth | Feeling unaccepted, so fears go unaddressed and growth stalls |
| Evolutionary | Reactions that once aided survival but are now out of proportion | Ancestral caution toward predators, overextended to pets |
| Sociocultural | Unhealthy social and cultural relationships and conditions | Growing up where dogs were feared and stories of attacks were common |
Putting perspectives together
In practice, most psychologists are eclectic: they mix ideas and methods from several perspectives when they diagnose and treat clients, because disorders rarely have just one cause.
The biopsychosocial model says you need three lenses to understand any psychological problem: biological (genes, brain chemistry), psychological (thoughts, learning, stress) and sociocultural (family, culture, poverty, discrimination). Most problems involve some mix of all three.
The diathesis-stress model focuses on two ingredients. A diathesis is an underlying vulnerability, usually genetic. Stress is a difficult life experience. A disorder becomes more likely when the two come together. Two people with the same vulnerability may have different outcomes depending on the stress they face, and heavy stress may not lead to a disorder without the vulnerability.
Worked examples
Try each one yourself first, then open the solution.
- Example 1
Applying the diathesis-stress model
Identical twins share a family history of depression. One twin goes through a painful divorce and job loss in the same year and later receives a diagnosis of major depressive disorder from a clinician. The other twin, with a calmer year, does not. Explain this using the diathesis-stress model.
Show the solutionHide the solution
- Step 1: Identify the diathesis: the shared family history suggests both twins carry a similar genetic vulnerability.
- Step 2: Identify the stress: only one twin faced major stressors (divorce and job loss).
- Step 3: Apply the model: a disorder is more likely when vulnerability and stress combine. The twin with both developed depression; the twin with the vulnerability but less stress did not.
- Step 4: Note the limit: the model predicts higher risk, not certainty, for anyone.
Answer: Both twins share the diathesis (genetic vulnerability), but only the twin who also faced severe stress developed depression, which fits the idea that disorders arise from vulnerability combined with stress.
- Example 2
The trap: is unusual the same as disordered?
Ravi spends about 20 hours a week building model trains, which none of his friends do. He enjoys it, keeps up his grades and has close friends. A classmate says Ravi must have a disorder because his hobby is so unusual. Evaluate the claim.
Show the solutionHide the solution
- Step 1: Check deviation: the hobby is unusual among his peers, so there's some deviation.
- Step 2: Check dysfunction: he keeps up his grades and friendships, so there's no meaningful interference with daily life.
- Step 3: Check distress: he enjoys the hobby, so there's no significant distress.
- Step 4: Conclude: deviation alone doesn't define a disorder. Without dysfunction or distress, the classmate's reasoning fails.
Answer: The claim isn't supported. Ravi's hobby is unusual, but it causes no dysfunction or distress, and deviation alone doesn't indicate a psychological disorder.
Common mistakes
- Using deviation from the norm as the whole definition of a disorder. Clinicians also weigh dysfunction and distress, and norms depend on culture.
- Mixing up the DSM and ICD. The DSM comes from the American Psychiatric Association; the ICD comes from the World Health Organization.
- Confusing the biopsychosocial and diathesis-stress models. Biopsychosocial lists three kinds of influences; diathesis-stress specifically pairs a vulnerability with stress.
- Assigning the 'lack of support and unfulfilled potential' explanation to the psychodynamic perspective. That's humanistic; psychodynamic focuses on unconscious conflicts.
On the exam
- Be ready to explain one disorder from two different perspectives, naming the specific cause each would point to.
- Questions about diagnosis often ask for one benefit and one drawback; giving access to treatment and the risk of stigma are both solid answers.
Connected topics
Videos
Check yourself
4 questions on 5.3 Explaining and Classifying Psychological Disorders. Pick an answer to see if you got it, and why.
Two people both check that their front door is locked before leaving home. Which additional detail would make a clinician most likely to consider whether one of them has a psychological disorder?
Researchers find that people with a family history of depression are more likely than others to develop depression after a major loss, but that many people with the same family history who face no major losses do not develop it. These findings best support
A school's mental health club asks students to say "a person with schizophrenia" rather than "a schizophrenic." What is the main goal of this change?
Which statement most accurately describes the DSM (the Diagnostic and Statistical Manual of Mental Disorders)?
0 of 4 answered