Public Release: 

The immune system and Alzheimer's disease

Netherlands Organization for Scientific Research

Utrecht researchers, funded by NWO, have determined the role played by brain cells from the immune system that are located close to dying memory cells. The research will help determine the causes of Alzheimer's disease.

In patients with Alzheimer's disease, the brain cells die off. The death of these neurones takes place primarily in the vicinity of so-called 'plaques'. These are lumps of the protein amyloid beta.

The NWO research shows that amyloid beta from the plaques stimulates the surrounding cells to produce 'CC chemokines'. In laboratory experiments, these substances attract new surrounding cells.

Two types of brain cells are found near the plaques, of which brain macrophages are one. Brain macrophages form part of the immune system of the brain and normally speaking destroy bacteria and waste products. The Utrecht research shows that the amyloid beta protein from the plaques causes the brain macrophages to produce toxic substances. These substances, oxygen radicals and compounds that promote inflammation, cause the brain cells to die off.

The other type of surrounding brain cells are the astrocytes. These star-shaped cells are normally involved in maintaining the structure of the brain. The role of the astrocytes in Alzheimer's disease is unclear. Laboratory experiments have shown that astrocytes do not produce toxic substances and that they in fact slow down the macrophages.

About 180,000 people in the Netherlands suffer from some kind of dementia. Of these, 130,000 have Alzheimer's disease. By the year 2050, the number of patients with Alzheimer's disease will have passed the 300,000 mark. That is equivalent to 1 in every 60 people in the country.

Alzheimer's disease leads to generalised atrophy of the brain tissue. Patients first lose their short-term memory. This is followed by changes in their behaviour, such as wandering and agitation. At a later stage, patients can no longer talk and are unable to recognise faces. They eventually require constant care.

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