Seeing as November is Alzheimer's Disease Awareness Month, it's only fitting that an intriguing discovery about Alzheimer's and genetics was reported last month. The gene of particular interest to researchers is called TREM2, and people with a variant on that gene appear to have triple the risk of developing Alzheimer's Disease. TREM2 may hold vital clues to late-onset Alzheimer's, and some scientists are calling it the most important Alzheimer's discovery in 20 years. So, what exactly is the TREM2 gene, and why are people so excited about it?
A normal brain (with a normal TREM2 gene) is helped by a good immune system; when brain inflammation (such as that which occurs in an individual with Alzheimer's Disease) strikes, the immune system helps by sending in anti-inflammatory molecules called microglia cells. These cells are also useful to the brain due for their ability to clean up amyloid plaque, a dangerous build-up responsible for killing brain cells. Basically, imagine the microglia cell wearing an apron and holding a tiny feather duster. With the TREM2 variant, however, these friendly microglia cells turn not only ineffective, but also calamitous. Now, instead of stopping inflammation, the cells release cytokines which actually produce inflammation. Whereas before microglia cells were bustling little workers, with the TREM2 variant they become lazy and stop cleaning plaque. This plaque can build up and destroy healthy brain cells; cell destruction plus inflammation is a sure recipe for decreased brain function and dementia-type symptoms. Alzheimer's and dementia are not the same, but scientists feel confident that TREM2 research indeed has a link to not just mental decay but Alzheimer's Disease specifically.
Studies by deCODE Genetics in Iceland found that people with the TREM2 variant were three times as likely to develop Alzheimer's as those with a normal TREM2 gene. At the same time as this study was progressing in Iceland, a research group from Universities in Canada, the U.S. and England were making similar discoveries. From a pool of 25,000 people, researchers found Alzheimer's patients quite likely to carry the rare TREM2 mutation when compared with a control group. Of course, most scientists are agreed that the TREM2 variation does not trigger the initial onset of Alzheimer's , but rather explains something about how dementia-like symptoms can occur. Researchers found that subjects over the age of 85 with the TREM2 mutation had not always developed Alzheimer's, but they did at the very least show signs of a slower-than-average mental capacity. Therefore, even if TREM2 research may not lead to a prevention for Alzheimer's, it might help develop a drug to target the TREM2 gene, stop the mutation from interfering with normal function and ease the inflammatory symptoms of Alzheimer's Disease. Even just a reduction of symptoms is big, big news for not just Alzheimer's patients and their families, but the United States healthcare system in general.
According to the 2012 annual report by the U.S. Alzheimer's Association, 5.4 million Americans are currently living with the disease, and it is estimated that 16 million will have the disease by 2050. One in eight older Americans has Alzheimer's, and it is the sixth-leading cause of death in this country. Alzheimer's can complicate the treatment of other diseases such as cancer and diabetes, and both doctors and patients must contend with the dangers of self-injury or malnutrition for patients who don't have round-the-clock care. Financially speaking, the impact of Alzheimer's is overwhelming - the U.S. Alzheimer's Association reports that patient care came at the cost of $200 billion just last year, and due to a rising elderly population the annual cost of care for Alzheimer's and other dementia-related diseases may rise as high as $1.1 trillion in the next 40 years. Many patients simply cannot cope with these astounding costs, but even on public health plans such as Medicaid, an Alzheimer's patient may pay 19 times as much as the average Medicaid user.
Clearly, developments in understanding and treating Alzheimer's are of the utmost importance when it comes to the health of the American people. Also, it is important to remember the unfortunate fact that Alzheimer's affects more than just patients - it affects the family members who often become Alzheimer's caregivers. It's difficult enough to manage the day-to-day needs, medical check-ups and emergency situations of an Alzheimer's patient, much less go through the taxing emotional experience of seeing a loved one slowly become less and less able. Many doctors report that caring for a family member with Alzheimer's can greatly increase mental and physical stress, leading caregivers to experience more healthcare issues themselves. The arduous effects of Alzheimer's disease on patients, families and healthcare systems in every nation makes recent TREM2 research all the most important. With scientists around the world reporting such similar and exciting genetic findings, it seems fair to hope that further understanding of Alzheimer's Disease, as well as further help for Alzheimer's patients, may be just around the corner.