===== Intracerebral Hemorrhage Risk Factors =====

[[Intracerebral hemorrhage]] (ICH) is a subtype of stroke characterized by bleeding directly into the brain parenchyma. It has high mortality and disability rates.

==== Major Risk Factors ====

=== Hypertension (HTN) ===
  * Most significant modifiable risk factor.
  * Leads to small vessel disease (lipohyalinosis, Charcot-Bouchard microaneurysms).
  * Classically associated with deep ICH (basal ganglia, thalamus, pons).

=== Cerebral Amyloid Angiopathy (CAA) ===
  * Age-related amyloid-β deposition in leptomeningeal and cortical vessels.
  * Associated with lobar hemorrhages.
  * Common in elderly; may cause recurrent bleeds.

=== Antithrombotic Therapy ===
  * Anticoagulants (warfarin, DOACs): ↑ risk, especially with supratherapeutic INR.
  * Antiplatelets: mildly increase risk, particularly in older patients or with CAA.

=== Alcohol Abuse ===
  * Chronic: leads to coagulopathy, liver dysfunction, and hypertension.
  * Acute: may provoke hypertensive surges.

=== Illicit Drug Use ===
  * Cocaine, amphetamines: cause acute hypertension and vascular damage.

=== Smoking ===
  * Promotes vascular injury and increases blood pressure.

=== Hypocholesterolemia ===
  * Low LDL and total cholesterol associated with increased ICH risk, especially lobar.

==== Non-Modifiable and Demographic Factors ====

=== Age ===
  * Risk increases with age.
  * CAA-related ICH more common in elderly.

=== Sex ===
  * Slightly more common in males.

=== Ethnicity ===
  * Higher incidence in Asian, Black, and Hispanic populations.

=== Genetic Factors ===
  * APOE ε2/ε4 alleles → linked to CAA-related ICH.
  * COL4A1/COL4A2 mutations → familial ICH syndromes.

==== Environmental and Emerging Risk Factors ====

=== Air Pollution (PM2.5) ===
  * Chronic exposure associated with increased ICH burden.
  * Disproportionately affects low-SES and urban populations.
  * See: [[Air Pollution as a Risk Factor for Intracerebral Hemorrhage]].

=== Other ===
  * Cerebral vascular malformations (AVMs, cavernomas).
  * Hemorrhagic transformation of ischemic stroke.
  * Neoplasms (primary or metastatic).
  * Coagulopathies (congenital or acquired).
  * COVID-19–associated coagulopathy.

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**Note:** Risk stratification may differ by hemorrhage location (deep vs lobar vs infratentorial).