In patients with haemophilia, which of these can increase the risk of cerebral microbleeds?

The correct option is "All of the above".

Cerebral microbleeds (CMBs) are small, chronic brain hemorrhages that are frequently detected using advanced neuroimaging techniques, such as susceptibility-weighted MRI. In patients with haemophilia, the baseline deficiency of clotting factors (Factor VIII or IX) already predisposes them to bleeding risks. However, several clinical factors can compound this risk and significantly increase the occurrence of cerebral microbleeds:

1. Cardiovascular Risk Factors:
Common cardiovascular risk factors, including hypertension (high blood pressure), hypercholesterolemia, and diabetes, damage the cerebral microvasculature over time. Chronic hypertension, in particular, leads to lipohyalinosis and arteriolosclerosis of small penetrating cerebral arteries, making them fragile and highly prone to microbleeds, especially in an individual with an underlying bleeding disorder.

2. Increased Age:
Aging is a well-established independent risk factor for cerebral microbleeds in both the general population and haemophilic patients. As individuals age, their blood vessels undergo degenerative changes, including loss of vascular elasticity and cumulative exposure to cardiovascular stress. In older patients with haemophilia, this vascular fragility, combined with lifelong clotting impairment, leads to a higher prevalence of CMBs.

3. Hepatitis C Infection:
A significant proportion of older haemophilia patients contracted Hepatitis C virus (HCV) through contaminated blood products before the implementation of rigorous screening protocols in the late 1980s and early 1990s. Chronic HCV infection is associated with systemic inflammation, endothelial dysfunction, and mixed cryoglobulinemia, all of which compromise blood vessel integrity. Furthermore, HCV-induced liver damage can lead to thrombocytopenia and worsened coagulopathy, further elevating the risk of cerebral microbleeds.

Therefore, because cardiovascular risk factors, increased age, and Hepatitis C infection all independently and synergistically increase the risk of cerebral microbleeds in this patient population, the correct answer is indeed "All of the above".