18 September 2023

The risk of brain haemorrhage may be transmissible via transfused blood, according to a new study., although the absolute risk remains low

Dr Gustaf Edgren of the Karolinska Institutet, Sweden, and his team explain that a common cause of spontaneous, recurring brain haemorrhages is the disease cerebral amyloid angiopathy (CAA).

This condition involves proteins building up in the brain’s blood vessels. Previous research has suggested that CAA may be transferable through neurosurgery or a type of growth hormone.

To further investigate this risk, the team used information from the Swedish-Danish transfusion database SCANDAT. It covers all electronically recorded blood donations and transfusions from 1968 to 2018.

Results showed that people who received donated blood from donors who went on to have recurring brain haemorrhages were at over twice the normal population risk of brain haemorrhage. The link was discovered using figures from Sweden, and then confirmed with data from Denmark.

The researchers state: “There are still evidence gaps for many aspects of blood donation and transfusion safety.”

They believe that these findings point to a risk factor for spontaneous brain haemorrhage. However, the team stress that the absolute risk to individuals is low.

Dr Edgren commented: “Blood transfusions are relatively common, which makes possible negative effects an important public health issue. However, in this case, it’s very unlikely that you’d suffer a brain haemorrhage from something transmitted through a transfusion.”

The more important implication is that it lends more support to the hypothesis that CAA can be transmitted between individuals.

Next, the team will search for specific proteins associated with the disease in biological samples and look at brain scans from the affected donors and patients.


Zhao J, Rostgaard K, Lauwers E, Dahlén T, Ostrowski SR, Erikstrup C, Pedersen OB, de Strooper B, Lemmens R, Hjalgrim H, Edgren G. (2023) “Intracerebral hemorrhage among blood donors and their transfusion recipients.” JAMA, doi: 10.1001/jama.2023.14445

Link: https://jamanetwork.com/journals/jama/fullarticle/2809417

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