Source: Flickr user Garry Knight.

According to a 2011 study, only cancer worried Americans more than being diagnosed with Alzheimer's disease, and for 22% of people responding, the risk of getting Alzheimer's disease was their No. 1 health concern. Given those numbers, it's probably not too surprising to learn that shares in Biogen Idec (BIIB 4.56%) jumped more than 6% on Tuesday after the company reported promising early stage results for BIIB-037, a treatment for Alzheimer's disease.

Tough to treat
Alzheimer's disease accounts for between 60% and 80% of all diagnosed cases of dementia, a general catch-all term for memory loss and the loss of intellectual abilities. Across the United States, an estimated 5 million people are living with Alzheimer's disease, the vast majority of which are over 65. Since there isn't a cure, the symptoms of Alzheimer's become progressively worse over time, and as a result, Alzheimer's is sadly the sixth leading cause of death among Americans, with the average person living just eight years after their symptoms become apparent to others.

Source: Alzheimer's Association.

Although there aren't any approved treatments specifically designed to treat Alzheimer's disease, there are medicines commonly prescribed to help treat various symptoms of the disease. Because this care is palliative, rather than curative, spending on healthcare is considerably higher for Alzheimer's patients than it is for patients without Alzheimer's disease. Overall, Medicare and Medicaid alone spend more than $140 billion annually treating Alzheimer's patients.

On the way
Since Alzheimer's disease is so tough to treat, it's hard not to be excited about any drug that shows promise in trials, even if those trials happen to be very early stage. And it doesn't get much earlier-stage than Biogen's BIIB-037, a drug that was most recently in phase 1 trials designed to establish safety, not efficacy.

Regardless, the results of BIIB-037 in patients were nothing short of impressive. The drug, which attempts to bind to and destroy amyloid plaques that build up in the brain that are thought to be behind the disease, successfully reduced amyloid levels, with those receiving higher doses or longer treatment duration seeing the biggest benefit. Additionally, BIIB-037 improved cognition versus placebo in the study, too.

The results are solid enough that Biogen, the $77 billion company behind top selling treatments for multiple sclerosis, plans to skip straight to phase 3 trials in a bid to speed along development. Even with advancing the drug into phase 3 trials quickly, however, it's unlikely that there will be results from such a late stage trial to support approaching the FDA for approval until 2018.

Massive global need
The number of Americans living with Alzheimer's disease is expected to grow substantially over the coming years, as 10,000 baby boomers turn 65 every day. That has industry trackers estimating that more than 1 million new cases of Alzheimer's will be diagnosed every year, or roughly one new case every 33 seconds. If that proves to be true, as many as 16 million Americans may be living with the disease by 2050. But it's not just Americans who would benefit from a new treatment. According to the World Health Organization, as many as 66 million people may be living with the disease worldwide by 2030. Since so many people are likely to have the disease and require treatment, there's a lot of reason for investors to be hopeful. However, there's still a tremendous amount of work to be done before we can say that Biogen's BIIB-037 may offer life-changing hope for millions of people.