There are many unanswered questions about Alzheimer's disease. One of
them is what exactly causes the disease; another is what factors put a person at risk for developing it.

Below are a few possible answers to these questions.

Plaques and tangles. People with Alzheimer's tend to have clumps
and strands of protein&mdash;also known as amyloid plaques and
neurofibrillary tangles&mdash;in and around the nerve cells in their brains.

Both of these formations are toxic, says William Thies,&nbsp;PhD, Senior Scientist in Residence, Medical and Scientific Relations, for the <a target="_blank" href="[BASEDOMAIN]/healthinfo/bouncelink.aspx?shortcut=alzheimers">Alzheimer's Association</a>.

"We know how they affect the brain's nerve cells. They trigger cell
death," he says. "And there's no doubt that these two proteins are
directly related to Alzheimer's disease."

However, researchers don't know yet why plaques and tangles form, or
whether they happen before Alzheimer's disease begins or as a result of
the disease.

Age. The likelihood of developing Alzheimer's doubles every five years after age 65.

"Certainly, age is the primary risk factor for Alzheimer's," says Dr.&nbsp;Thies.

Genetics and family history. Scientists have found genetic links
to Alzheimer's disease. Having a family history of Alzheimer's also seems to increase your risk
for the disease. However, it's impossible to predict who will and won't
get Alzheimer's based on family history alone, notes the Alzheimer's Association.

Artery disease. "Other possible risk factors center around
conditions associated with blood vessel disease," says Dr.&nbsp;Thies,
including heart disease, diabetes, stroke, high blood pressure and high
cholesterol.

All of these conditions damage the arteries, reducing the supply of
oxygen to the brain and possibly disrupting connections between nerve
cells.

Research continues

The Alzheimer's Association notes that there probably isn't just one
factor that leads to the disease. Instead a combination of risks may
work together to cause Alzheimer's. These factors may affect each
person differently.

For more information, visit <a target="_blank" href="[BASEDOMAIN]/healthinfo/bouncelink.aspx?shortcut=alzheimers">alz.org</a>.

reviewed 11/29/2017

Causes and risk factors for Alzheimer's disease

A look at some of the factors that may influence whether or not a person gets Alzheimer's disease.