7.2 Post-Traumatic Stress Disorder (PTSD): Prevalence, Risk Factors, & Clinical Course

Epidemiology & Prevalence

• Two large U.S. national epidemiological studies (using DSM-5):
  • Lifetime prevalence range: $6.1\% - 8.3\%$.
  • 12-month (annual) prevalence: $4.7\%$.
• Higher‐risk occupational / situational groups:
  • Military veterans, firefighters, emergency medical personnel.
• Highest PTSD rates ("one-third to > one-half" of those exposed):
  • Survivors of rape.
  • Military combat & captivity.
  • Victims of ethnically or politically motivated internment / genocide.
• Developmental variation:
  • Preschool children generally show lower measured prevalence, possibly reflecting under-developed diagnostic criteria for young ages.
• Racial / ethnic disparities (DSM-IV data):
  • Higher PTSD prevalence among U.S. Latinx, African-American, and American Indigenous peoples vs. White/Caucasian groups.
  • Contributing factors: prior adversity, racism/discrimination, socioeconomic inequities, variable treatment access/quality.

Trauma Type vs. Conditional Risk (Slide Graph)

• Table below reflects (a) percentage of population experiencing each trauma & (b) percentage of those individuals who develop PTSD.
  • Rape: $5.4\%$ exposed → $49\%$ develop PTSD (highest conversion rate).
  • Other sexual assault (e.g., groping): $23.7\%$ → $23.7\%$ PTSD.
  • Being badly beaten: $31.9\%$ → $31.9\%$ PTSD.
  • Natural disaster: $3.8\%$ → $3.8\%$ PTSD.
  • Mugged / threatened w/ weapon: $8\%$ → $8\%$ PTSD.
  • Serious car crash: $2.3\%$ → $2.3\%$ PTSD.
  • Witnessing killing / serious injury: $7.3\%$ → $7.3\%$ PTSD.
  • Sudden unexpected death of loved one: $14.3\%$ → $14.3\%$ PTSD.
  • Other trauma (lumped): $9.2\%$ → $9.2\%$ PTSD.

Age of Onset & Course

• Possible at any age once >1 yr old.
• Symptom onset:
  • Typically within 3 months post-trauma.
  • Delayed expression possible (months–years) → some early symptoms appear immediately but full criteria met later.
  • Acute Stress Disorder (ASD) often diagnosed first.
• Duration:
  • ~$50\%$ of adults recover completely within 3 months.
  • Others symptomatic >12 months; some for decades.
• Recurrence / intensification triggered by reminders, ongoing stressors, or new traumas.

Risk & Protective Factors Framework

• Three temporal buckets:
  1. Pre-traumatic (before event)
  2. Para-traumatic (during event)
  3. Post-traumatic (after event)

Pre-traumatic Factors

• Temperament & personality:
  • Childhood emotional problems (<6 yrs) – externalizing, anxiety.
  • Prior mental disorders: panic, depressive, obsessive-compulsive, etc.
  • High neuroticism / negative affectivity → greater risk.
  • Premorbid impulsivity → externalizing PTSD pattern; ↑ substance use, aggression.
• Environment / life history:
  • Lower socioeconomic status, low education.
  • Childhood trauma/adversity: economic deprivation, family dysfunction, parental separation, parental death.
  • Lower intelligence (cognitive reserve).
  • Racism, ethnic discrimination.
  • Family psychiatric history.
• Protective: robust pre-event social support.
• Genetic/physiological:
  • Twin & molecular studies → moderate heritability.
  • GWAS: 3 genome-wide significant loci; ancestry-specific effects.
  • Epigenetic mechanisms likely contribute.

Para-traumatic Factors (during trauma)

• Objective severity of trauma (not all events equally severe).
• Perceived threat to life → strong predictor.
• Interpersonal violence, esp. caregiver-related (children).
• Military-specific: perpetrating violence, witnessing atrocities.
• Immediate responses that persist: dissociation, fear, panic.

Post-traumatic Factors

• Temperamental: negative appraisal, poor coping strategies, presence of Acute Stress Disorder.
• Environment:
  • Repeated reminders, ongoing adversity, financial or trauma-related losses.
  • Forced migration (refugee status), high daily stress load.
  • Continuing discrimination (racial/ethnic) → more chronic PTSD in African-American & Latinx adults.
• Protective: high-quality social support, family stability (children).

Sex & Gender Considerations

• Lifetime prevalence:
  • Women: $8 - 11\%$.
  • Men: $4.1 - 5.4\%$.
• Women exposed to:
  • Greater rates of childhood sexual abuse & adult sexual assault—traumas with highest PTSD risk.
  • Experience longer PTSD duration vs. men.
• Possible additional mechanisms: sex differences in emotional/cognitive processing, reproductive hormone influences.
• Even when men & women exposed to identical stressors, risk gap persists.

PTSD & Suicidality

• Trauma (childhood abuse, sexual assault) elevates suicide risk in civilians & veterans.
• PTSD independently increases likelihood of progression from suicidal ideation → plan/attempt, beyond mood-disorder effects.
• Adolescents: PTSD strongly linked to suicidal thoughts/behaviors, even after controlling for comorbidities.

Comorbidity Patterns

• PTSD frequently co-occurs with ≥1 other mental disorder:
  • Depressive disorders (unipolar, bipolar).
  • Anxiety disorders.
  • Substance use disorders.
• Elevated risk for major neurocognitive disorder.
• TBI intersection: women with mild TBI show higher subsequent PTSD rates.
• Children’s comorbidity profile differs:
  • Common: Oppositional Defiant Disorder, Separation Anxiety Disorder.

Practical / Clinical Implications & Connections

• Diagnosis must consider developmental stage; criteria for young children evolving.
• Social support before & after trauma is a modifiable protective factor → target for intervention.
• Screening high-risk occupations & populations (veterans, first responders, survivors of interpersonal violence) is crucial.
• Understanding gender, racial, and socioeconomic contexts can guide culturally sensitive assessment & treatment.
• Genetic insights (GWAS loci, epigenetics) may inform personalized medicine approaches in the future.
• Suicide prevention protocols should include PTSD assessment and management.