What is CAA?

The disease CAA (Cerebral Amyloid Angiopathy) occurs in the small blood vessels of the brain. Amyloid (toxic protein) accumulates in the wall of these vessels. This causes repeated cerebral haemorrhages and infarctions. This leads to paralysis, dementia and eventually to death. One in four people over the age of 60 get CAA. This number is increasing. CAA is recognized as one of the most important causes for cerebral hemorrhages and dementia for elderly people (60+).


HCHWA-D (full name: Hereditary Cerebral Haemorrhages with Amyloidosis – Dutch type) is an inherited form of CAA that, unlike CAA, can be determined with certainty during life. This variant is revealed at a relatively young age, around 45 years, and originated in Katwijk. Hence, it is popularly called the ‘Katwijk disease’. Children of hereditary carriers have a 50% chance of getting the disease. Research on these families can not only lead to treatment of this rare hereditary variant of CAA, but can also lead to the key for therapy for the much more common non-hereditary variant of the disease.


CAA is not a new disease. The lack of awareness has to do with fact that, for many years, the disease could not be diagnosed during life. Only recently, it has been discovered that brain scans can show signs of the existence of disease. Even though the indications do not offer certainty, they have led to the awareness that CAA is a common disease. The full extent of the effects of CAA has also recently become known. CAA is the cause for a quarter of all cerebral haemorrhages in older people and the disease is increasingly recognised as a major cause of loss of brain functions and dementia in older people. HCHWA-D was discovered in the 1980s and recognised years later as a hereditary variant of CAA. Watch a film about CAA here.