2.2 Developmental Stages & Biopsychosocial Assessment

The TCO's Knowledge statement K1 asks the PMH nurse to apply developmental theory — specifically Erikson and Piaget — to psychiatric assessment. Developmental stage matters because the same symptom can mean something different depending on where a patient sits across the lifespan: withdrawal in a toddler is not evaluated the same way as withdrawal in a widowed 80-year-old.

Erikson's Psychosocial Stages

Erik Erikson described eight sequential stages, each centered on a psychosocial conflict that must be resolved to build a healthy foundation for the next stage. Unresolved conflicts do not disappear — they resurface as vulnerability later in life.

For the exam, connect the stage to the assessment question being asked: an adolescent client struggling with identity vs. role confusion may present with intense peer-focused behavior and experimentation that would be developmentally atypical — and clinically concerning — in a school-age child still working through industry vs. inferiority. Similarly, a grieving older adult reflecting on regrets is working through ego integrity vs. despair; the nurse assesses whether that reflection is adaptive life review or a marker of depression.

Piaget's Cognitive Stages

Jean Piaget described four stages of cognitive development that shape how a patient understands illness, treatment, and consequences — directly relevant to consent, teaching, and communication planning covered later in Chapter 3.

• Sensorimotor (birth-2 years): Learning occurs through senses and motor activity; object permanence develops.
• Preoperational (2-7 years): Symbolic and magical thinking; egocentrism; cannot yet reason logically about cause and effect. A young child may believe their "bad thoughts" caused a parent's illness.
• Concrete operational (7-11 years): Logical thinking about concrete, tangible events; understanding of conservation and reversibility, but abstract reasoning is still limited.
• Formal operational (11+ years): Abstract, hypothetical, and deductive reasoning develops — the cognitive capacity needed to fully grasp illness explanations, weigh long-term consequences, and participate meaningfully in treatment planning.

A patient's Piagetian stage — not merely chronological age — should guide how the nurse explains diagnoses, medication risks, and safety plans.

Biopsychosocial Assessment

The biopsychosocial model organizes the psychiatric intake into three interacting domains, none of which can be assessed in isolation:

Biological — genetic and family psychiatric history, current and past medical conditions, medications, substance use, sleep, nutrition, and physical review of systems. A strong family history of bipolar disorder or suicide, for example, meaningfully raises risk stratification for a presenting patient.

Psychological — mental status findings, coping style, defense mechanisms, personal psychiatric history, prior treatment response, trauma history, and current stressors. This domain captures how the patient experiences and manages internal distress.

Social — family structure and relationships, cultural and religious background, socioeconomic status, housing stability, occupational or academic functioning, legal involvement, and available support network. Social data frequently determines what is realistically achievable in a treatment plan (Chapter 3 builds directly on this).

Normal versus Abnormal Behavior

Because the biopsychosocial and developmental frameworks are contextual, a core assessment skill is distinguishing normal variation from pathology. A toddler's tantrums (autonomy vs. shame/doubt) are developmentally expected; the same explosive, injurious outbursts in a 14-year-old are not, and warrant evaluation for disruptive mood dysregulation disorder or another diagnosis. Grief following a loss produces sadness, sleep disruption, and preoccupation with the deceased that overlaps symptomatically with depression — but grief is time-limited and fluctuates, while major depressive disorder is pervasive and persistent (Section 2.4 develops this distinction further). Cultural norms also shape what counts as "abnormal": expressions of distress, family involvement in decision-making, and beliefs about mental illness vary widely, and the nurse must assess within — not against — the patient's cultural framework (expanded in Section 3.4).

Lifespan and Aging Considerations

Assessment must also account for expected changes across the lifespan, particularly in older adults. Mild slowing in processing speed and word-finding are normal aging changes and should be distinguished from the more pervasive, functionally impairing decline of a neurocognitive disorder (Section 2.7). Older adults also carry a higher risk of atypical symptom presentation — depression may present primarily as somatic complaints or irritability rather than sadness, and grief, retirement, loss of independence, and bereavement are common late-life stressors that the nurse should assess for directly rather than assuming any change in mood or function is simply "part of aging."​

Taken together, developmental theory and the biopsychosocial model give the PMH nurse a structured way to ask not just "what symptoms does this patient have" but "are these symptoms expected for this person, at this stage of life, in this social and biological context" — the reasoning skeleton for every diagnosis that follows in this chapter.