Sympathomedullary Pathway
Life Changes and Stress: Holmes and Rahe
Holmes and Rahe proposed that significant life changes — whether positive or negative — require psychosocial adjustment and therefore constitute stressors. They developed a systematic method for quantifying life stress exposure and demonstrated a relationship between cumulative life stress and subsequent illness.
The Social Readjustment Rating Scale (SRRS)
Holmes and Rahe (1967) developed the Social Readjustment Rating Scale (SRRS) — a measure of life stress based on a list of 43 life events, each weighted by the amount of social readjustment it was judged to require. The scale was constructed by asking a diverse sample of Americans to rate the amount of readjustment each event required, using marriage as an anchor point (set at 50 Life Change Units, LCU). Events were then ranked and weighted accordingly.
Selected items and their LCU values:
| Life event | LCU |
|---|---|
| Death of spouse | 100 |
| Divorce | 73 |
| Marital separation | 65 |
| Imprisonment | 63 |
| Death of close family member | 63 |
| Personal injury or illness | 53 |
| Marriage | 50 |
| Redundancy/job loss | 47 |
| Retirement | 45 |
| Pregnancy | 40 |
| Christmas | 12 |
| Minor violations of the law | 11 |
An individual's stress score is the sum of LCUs for all events experienced in the previous 12 months. Holmes and Rahe proposed that scores above 300 LCU in a year indicated high risk of illness; 150–299 indicated moderate risk.
Evidence: Rahe et al. (1970) — US Navy Study
Rahe et al. (1970) conducted a prospective study with approximately 2,500 US Navy personnel. Prior to deployment, participants completed the SRRS for the previous six months. Illness records were then monitored during the seven-month cruise. A significant positive correlation was found between LCU scores and illness rates during deployment — those with higher pre-deployment LCU scores experienced more illnesses. This was a prospective design, which is stronger than retrospective recall studies for establishing a temporal relationship between stress exposure and illness outcomes.
Evaluation
The SRRS was highly influential as a standardised, operationalised measure of life stress. Limitations: (1) It treats all events of the same LCU value as equally stressful, ignoring individual differences in appraisal — a divorce may be devastatingly stressful for one person and a relief for another. (2) It includes positive events (marriage, pregnancy, Christmas) as stressors — the assumption that positive life changes require readjustment and are therefore stressful is contested. (3) Retrospective recall of life events is subject to memory bias. (4) The correlation between LCU and illness is significant but modest, and correlation does not establish causation — a third variable (e.g. poor health) may cause both life disruption and illness. (5) Cultural specificity — the LCU values were derived from a Western, largely American sample and may not generalise cross-culturally.
Key Takeaways
- SRRS (Holmes and Rahe, 1967): 43 life events each weighted in Life Change Units (LCU). Sum of LCUs = measure of life stress. Marriage (50 LCU) was the anchor; death of spouse (100 LCU) tops the list.
- Threshold guidance: SRRS score >300 LCU in 12 months = high risk of illness; 150–299 = moderate risk.
- Rahe et al. (1970) — US Navy: prospective study (N≈2,500); pre-deployment LCU scores predicted illness rates during 7-month cruise. Significant positive correlation. Prospective design stronger than retrospective.
- Key limitation: ignores individual appraisal — same LCU value assigned to event regardless of whether it was welcomed or catastrophic for that individual.
- Includes positive events as stressors (marriage, pregnancy, Christmas) — contested assumption that any change requiring adjustment is stressful.
- Correlation between LCU and illness is significant but modest. Retrospective recall bias; cultural specificity of LCU values; correlation ≠ causation.