Frequently asked questions

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, which lead to paralysis, dementia and eventually death. One in four people over the age of sixty get CAA. And this number is increasing.


Is it hereditary?

Yes, there are various hereditary variants. The Dutch variant HCHWA-D is the largest and best-documented group. 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 relatively early in life, around the age of 45. It was first identified in Katwijk, Holland, which is why the condition is commonly referred to as the ‘Katwijk disease’. Children of hereditary carriers have a fifty percent chance of developing the disease. Research on these families could not only result in treatment of this rare hereditary variant of CAA, but could also lead to the key for therapy for the much more common, non-hereditary variant of the disease.


What are the symptoms?

The symptoms consist of repeated cerebral haemorrhages and infarctions. This leads to the acute or gradual decline of brain functions, resulting in paralysis and dementia. Some people die immediately, others deteriorate with each new haemorrhage and die after a period of suffering and uncertainty.


How do you know if you have CAA?

CAA is only diagnosed in people after they have had a cerebral haemorrhage. If this haemorrhaging meets the so-called ‘Boston criteria’, it is likely that the cause is CAA. The criteria are: the person is 55 or older, has had one or more small haemorrhages in specific places in the brain and no other explanations for the haemorrhages can be found.

You cannot pre-test whether you have CAA or take preventative action. Unfortunately, there is still too little known about the disease for this. We still do not know much about its origins, or why and when it strikes.

People with the hereditary variant can be genetically tested. For them, the disease can be identified with a hundred percent certainty before the onset of symptoms.


What can you do about CAA?

There is still not much known about the cause of this brain disease and no medicines are available to treat it. However, CAA research has an advantage that other diseases do not, in that researchers know where to look for the solution – by identifying and researching carriers of the Dutch hereditary variant. If these people are tested, they will know with 100 percent certainty that they are carriers and that they have a high chance of developing the disease at a young age. This means that you can research the disease during an early stage in life, before people get the symptoms. Thanks to this group, scientists can map the disease’s progression and discover the cause of the disease. Based on the insights gained thereby, there can be a more targeted search for effective treatments.


How common is the disease?

It has recently become clear that CAA is a common disease. One in four people over sixty has CAA and therefore a large chance of suffering from cerebral haemorrhages. As a result of the aging population, the number of people with CAA is increasing. The older a person is, the greater the chance of CAA.

An estimated 500-1500 people in the Netherlands have the hereditary variant. Carriers have a fifty percent chance of passing it on to their children.


Why is CAA so unknown if so many people have it?

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 has it been discovered that brain scans can diagnose symptoms of the 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 of 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 the elderly. HCHWA-D was discovered in the 1980s and recognised years later as a hereditary variant of CAA.


What does the CAA Foundation intend to accomplish?

The CAA Foundation is the only Foundation dedicated globally to raising funds for research into CAA. Since the disease is still unknown to the general public, the Foundation focuses not only on raising funds, but also on outreach activities to bring national attention to this common disease.


How did the CAA Foundation emerge?

Jan Fens, a carrier of the hereditary gene, decided to establish the CAA Foundation after discovering that, whilst there was no medicine for CAA, he and the other carriers could be the key to the solution. Research into the hereditary group had been dormant for years and there was not enough money to come closer to a solution. There was no driving force to put CAA on the map or to raise funds for research. Jan’s work with the Foundation focusses on increasing awareness of this common disease and generating funds through donations. He hopes that the solution will be found quickly, so that there will be medical treatment for not only his own children, if they too suffer from the hereditary burden, but also for all those with the hereditary gene as well as other Dutch people who will contract non-hereditary CAA.


How is the Foundation structured?

The board consists of six people. The board is supervised by the Board of Trustees, which monitors whether the main objective is met (raising funds earmarked for research into CAA and HCHWA-D) and approves expenditure. The Board of Trustees consists of Frank Blom (owner of Frame Vastgoed, Harry Groen (former councillor of Amsterdam and former mayor of Noordwijk) and Martin Soeters (recently retired, former CEO of Nova Nordisc pharmaceutical company). In addition, the HCHWA-D patient association has a seat on the board. This position is filled by Koos van Rijn. There is also a ‘Medical Advisory Board’ of sixteen people, consisting of scientists and medical specialists from around the world. The chairman is Prof. Mark van Buchem (LUMC). The Medical Advisory Board ultimately decides what research will be funded. The board is obliged to take on these decisions.


Why is there also a CAA Association?

In addition to the CAA Foundation, an Association has recently been established comprising all national and international (medical) CAA specialists in order to join forces and encourage research on CAA. The Association organises a CAA conference once every two years, each time in a different country. For dates and information, go to


Why is research needed?

It has only recently become clear just how common this disease is. However, it is unknown why and when someone gets CAA. Testing someone for the disease is not possible and there is currently no cure. People who have CAA usually only discover it after they have had a cerebral haemorrhage. Being able to diagnose CAA before it strikes is the ultimate goal, in order to be able to take preventative measures, reduce a lot of personal suffering and lower the significant medical costs. Unlike many other diseases, scientists do know where to look for the solution, but currently there are insufficient funds to carry out the necessary research.

The solution lies with hereditary carriers, who develop symptoms of the disease at a relatively young age. Precisely because it is hereditary, researchers know who they should research. This makes it possible to map the course of the disease, testing people before the haemorrhaging occurs. Scientists ensure us that they are on the verge of a breakthrough but, due to lack of funds, research into this group has been dormant for years. The quicker funds are raised, the quicker this ticking time bomb can be diffused.


Do research institutes, the government or the (commercial) pharmaceutical industry also research CAA?

Research into CAA is conducted at various university research institutes worldwide. A number of these institutes are based in the Netherlands: in the LUMC (Leiden), the Radboud UMC (Nijmegen), the VUmc (Amsterdam) and the Erasmus MC (Rotterdam). In the LUMC, research that focuses specifically on the Dutch variant (HCHWA-D) has been carried out for years. The research that these Dutch institutes conduct is partly financed by the government, partly by charitable funds and partly by pharmaceutical companies. Given the scale of the problems that CAA causes in society, the scope of the current research into this disease is inadequate and this is why the Foundation was established.


What is the difference from Alzheimer’s disease?

The disease CAA is often bracketed together with Alzheimer’s disease. This is not correct. CAA and Alzheimer’s are two different brain diseases. Alzheimer’s is a disease in which there are deposits of a protein called amyloid in the brain tissue. The disease ultimately leads to dementia. CAA is a disease in which the same amyloid accumulates at a different place in the brain: in the walls of the small blood vessels that provide blood to the brain, which results in haemorrhaging and infarctions in the brain. These changes lead to paralysis, dementia and premature death. So, whilst both CAA and Alzheimer’s involve the accumulation of amyloid in the brain, and both can lead to dementia, they are two completely different diseases.


What is dementia?

There are various brain diseases that cause dementia, of which CAA is one. Several areas of the brain are affected with dementia: the mental abilities (e.g. memory), mood and behaviour. When dementia is caused by problems in the brain vessels, it is called vascular dementia. So CAA causes vascular dementia.


Is the money for research allocated properly?

All board members, members of the Board of Trustees and the Medical Advisory Board commit their services without any form of salary, fees or fixed expenses. All donations directly benefit research.


As a patient, where can I go for help?

There is no worldwide CAA patient association yet. However, the carriers of the hereditary Dutch CAA variant have joined in the HCHWA-D Association:


What does the logo mean?

The key in the CAA Foundation logo symbolises the fact that the solution for this disease is at hand. The hereditary carriers – people who sadly get the disease at a relatively young age ­ – are the key to the cure for CAA. The fact that it is hereditary makes it easier for scientists to find subjects for their research. This allows the proper mapping of the course of the disease and they can study patients before haemorrhaging occurs. Based on the knowledge obtained from such research, there can be a much more focused search for effective treatments, which increases the chance for a solution for the disease.