Week 2: Notes on Diagnosing Psychological Disorders (Lecture-Driven Overview)

Diagnosing psychological disorders provides a framework for understanding and treating conditions not visible through medical tests, relying on symptoms, behaviors, thoughts, and feelings. This process guides treatment, prognosis, professional communication, and eligibility for services. However, diagnoses don't capture the full individual experience, can carry stigma, and must consider cultural contexts.

Assessment vs. Diagnosis

Assessments gather information on functioning and symptoms, while diagnosis is a label that informs treatment, but doesn't fully describe a person's functioning. Not all assessments lead to a formal diagnosis.

Diagnostic Models and Systems

Psychological diagnoses operate via:

  • Categorical approach: Disorders are discrete (you have it or you don't).

  • Dimensional approach: Disorders exist on a spectrum (e.g., mild, moderate, severe), reflecting real-world variation.

  • Prototypical approach (DSM-style): Disorders have core features with variability in additional symptoms. The DSM-5-TR (used in the US) follows this, incorporating dimensional elements for severity. ICD codes are used globally for billing and classification. Education settings use distinct categories (IDEA) focused on school functioning impairment.

Language and Ethical Considerations

Language in diagnosis significantly impacts perception. Clinicians should use person-first language (e.g., "person with schizophrenia") unless identity-first is preferred by the individual/group (e.g., "autistic person"). Avoid loaded terms and communicate diagnoses clearly and sensitively, balancing honesty with managing potential stigma and legal implications.

Evaluation Process

This involves differential diagnosis (narrowing from broad possibilities to specific diagnoses) using evidence-based practice. Assessments must be psychometrically reliable (consistent) and valid (measure what they intend to). Standardization and norms are crucial; clinicians must interpret results cautiously if a client's background differs from norming samples.

Assessment Methods

A multimethod, multi-informant approach integrates various sources:

  • Medical examination: Rules out physical causes.

  • Clinical interviews: Structured, semi-structured, or unstructured; build rapport, observe behavior, gather information, and corroborate reports.

  • Mental Status Exam (MSE): A screening tool assessing appearance, behavior, thought, mood, cognition, and perception.

  • Behavioral assessments: Direct observation of behavior in context (ABC data).

  • Self-monitoring/informant reports: Daily life data from clients or caregivers.

  • Rating scales: Standardized questionnaires for screening or gathering diagnostic information.

  • Projective testing: (Limited contemporary use) Reveals unconscious conflicts via ambiguous stimuli.

  • Personality inventories: Self-report tests (e.g., MMPI-2) with validity scales to assess response style.

  • Cognitive (intelligence) testing: Quantifies cognitive abilities and identifies strengths/weaknesses. Modern IQ uses a deviation IQ (mean = 100, standard deviation = 15). Scores below 70 indicate intellectual disability range; 130 and above, gifted. Cultural and linguistic biases are key considerations.

  • Neuropsychological testing: Focuses on neurological functioning and cognitive processes for conditions like TBI or dementia.

  • Neuroimaging (MRI, CT): Primarily for ruling out medical causes of symptoms, not diagnosing psychiatric disorders directly.

  • Play-based/developmental assessments: Observes children in naturalistic settings for developmental delays.

Practical Takeaways

Clinical assessment is complex, requiring multiple data sources and combining objective measures with clinical judgment to minimize bias. Be mindful of each method's limitations and normative assumptions. The DSM-5-TR standardizes diagnoses, while ICD codes facilitate billing. Ethical, legal, and social considerations (stigma, insurance barriers, cultural language preferences) are paramount.