What is a psychological disorder?
A psychological disorder is a pattern of thoughts, feelings or actions that is unusual, upsetting and gets in the way of daily life. Abnormal simply means "away from the normal".
Psychologists check the 4 Ds:
- Deviance: very different from what the society expects.
- Distress: the person feels upset, sad or scared.
- Dysfunction: work, study, sleep or self-care break down.
- Danger: risk to self or others. This is seen only in some cases.
One D alone is not enough. A genius is "deviant" but not disordered. We also look at culture: what is normal in one place may be unusual in another.
Two ways to see abnormality: (1) deviation from social norms, and (2) maladaptive behaviour, which means behaviour that stops a person from coping well. Psychologists prefer the second, because norms change and can be unfair.
History of ideas about abnormal behaviour
- Supernatural view (ancient times): evil spirits or magic were blamed. People used rituals and exorcism (driving out spirits).
- Biological (organic) view: Greek doctors Hippocrates and later Galen said illness of the mind comes from the body and brain.
- Psychological view: problems come from how we think, feel and learn.
- Middle Ages: superstition and demons came back, though some monasteries still cared for the ill.
- Renaissance: curiosity and humane ideas grew. Johann Weyer said the mind can be sick just like the body.
- Age of Reason and Enlightenment (17th–18th centuries): careful observation and reason began to replace blind faith.
- Reform movement: hospitals removed chains and gave kind care (moral therapy). Deinstitutionalisation later moved patients back to the community.
- Today: the biopsychosocial (interactional) view: body, mind and society act together.
Classification of psychological disorders
To classify is to sort things into groups with clear signs. It helps experts use the same names, choose treatment and do research.
- DSM: Diagnostic and Statistical Manual of Mental Disorders, by the American Psychiatric Association. Latest: DSM-5-TR (2022). It describes each disorder with a list of symptoms, how long they last, and how much they affect life.
- ICD: International Classification of Diseases, by the World Health Organization (WHO). Latest: ICD-11, in which mental, behavioural and neurodevelopmental disorders form one chapter. India uses ICD for health records.
Labels help, but they can also bring stigma (shame). So we say "a person with schizophrenia", not "a schizophrenic".
Factors underlying abnormal behaviour
Biological factors
Genes (a disorder can run in families), faulty brain chemicals called neurotransmitters (such as serotonin, dopamine and GABA), brain structure, and infections or injuries.
Psychological factors
- Psychodynamic: hidden conflicts between id, ego and superego from childhood.
- Behavioural: faulty behaviour is learned by conditioning and copying.
- Cognitive: irrational beliefs and negative thinking.
- Humanistic-existential: blocked growth and no sense of meaning.
Sociocultural factors
Family conflict, poverty, war, violence, prejudice and cultural pressure. Family systems and social networks can protect or harm.
Diathesis-stress model
A diathesis is an inborn weakness (a biological tendency). A stressor is a tough life event. A disorder appears when the weakness and the stress together cross a threshold. Two people with the same stress can react differently.
Try it
In the 3D free-play step, set diathesis to 8. Now slowly raise stress. At what stress value is the line crossed? Now set diathesis to 3 and repeat. Predict first, then check. Write one sentence on why the same exam stress affects two friends differently.
Key formulas and definitions
- 4 Ds: Deviance, Distress, Dysfunction, Danger
- DSM-5-TR: American Psychiatric Association; ICD-11: World Health Organization
- Biopsychosocial = biological + psychological + sociocultural factors
- Diathesis (inborn weakness) + stressor ≥ threshold → disorder may appear
Worked examples
1. Ravi scores 99% in maths, far above his class. Is this abnormal?
He is deviant (unusual) but there is no distress, no dysfunction and no danger. So it is not a disorder. One D alone is not enough.
2. Meena feels so scared of crowds that she has stopped going to college for 3 months and cries every day. Which Ds are present?
Deviance (fear much stronger than normal), distress (daily crying) and dysfunction (missed college). Danger is not seen. A psychologist should assess her.
3. Two cousins lose their jobs. One becomes seriously depressed; the other is sad for a week and recovers. Explain.
Diathesis-stress model: the stress is the same, but the first cousin may have a higher inborn weakness (for example depression runs in the family). Weakness + stress crossed the threshold only for him.
4. Why do doctors across the world use DSM or ICD?
So that every expert uses the same name for the same set of symptoms. This helps diagnosis, choosing treatment, record-keeping and research.
Common mistakes
- Thinking one unusual trait (one D) makes a disorder. Look for several Ds together.
- Mixing up DSM (American Psychiatric Association) and ICD (World Health Organization).
- Believing only the body or only the mind causes disorders. Most have biological, psychological and social causes together.
- Saying "diathesis" means stress. Diathesis is the inborn weakness; stress is the trigger.