HRV & Brain Health

Methods

UK Whitehall II cohort longitudinal follow-up with cognitive testing

Key Findings

• Low RMSSD: cognitive decline 3 years faster per decade
• Low HF-HRV: cognitive decline 3.5 years faster per decade
• Low RMSSD: 37% higher odds of low cognitive function
• HRV in midlife predicts long-term cognitive trajectory

Limitations

Observational study, predominantly white-collar workers

Methods

Cross-sectional analysis of older adults in Einstein Aging Study

Key Findings

• Higher HF-HRV associated with better global cognition
• Lower HF-HRV associated with mild cognitive impairment
• Extends prior findings on HRV as early dementia indicator
• Community-based cohort increases generalizability

Limitations

Cross-sectional design

Methods

Review of HRV physiology, measurement, and clinical applications

Key Findings

• HRV reflects bidirectional brain-heart communication
• Useful for predicting cardiovascular, neurological, and psychiatric outcomes
• Different HRV parameters capture different aspects of autonomic function
• Integration of HRV into clinical practice growing
• Wearable technology enabling population-scale HRV monitoring

Limitations

Review paper, no new primary data

Methods

Prospective treatment study with baseline HRV assessment

Key Findings

• Higher HRV: 9.7 fewer headache days/month after treatment
• Lower HRV: only 6.2 fewer headache days/month
• Autonomic dysfunction common in chronic migraine
• HRV may serve as treatment response predictor
• HRV lowest during migraine attacks (ictal period)

Limitations

Single treatment studied, replication needed

Methods

Meta-analysis and longitudinal studies of HRV in PD

Key Findings

• PD associated with reduced overall HRV
• Both sympathetic and vagal activities decreased
• HRV alterations detected before motor symptoms appear
• Lower HRV predicts cognitive decline and mortality
• Freezing of gait linked to very low HRV in OFF states

Limitations

Medications affect HRV, complicating interpretation

Methods

Longitudinal HRV monitoring in concussed athletes

Key Findings

• pNN50 decreased at 3 days post-concussion
• HRV recovered to baseline by ~3 weeks
• Persistent low HRV may indicate incomplete recovery
• Autonomic dysfunction common after mild TBI
• HRV may complement symptom-based return protocols

Limitations

Individual recovery timelines vary significantly

Methods

Literature review of HRV and cognitive function studies

Key Findings

• Higher HRV associated with better executive function
• Vagal tone supports prefrontal cortex activity
• Low HRV linked to cognitive impairment and dementia risk
• Relationship holds across age groups
• Interventions improving HRV may support cognition

Limitations

Bidirectional relationship, causation unclear