Source: Flickr user Loren Kerns.

Alzheimer's disease may not be a swift killer, but with life expectancies rising in practically every country around the world, it is nonetheless growing to be a serious health problem.

According to the Alzheimer's Association, Alzheimer's disease, which is characterized by a progressive decline in cognitive function caused by the sticking of plaques known as beta amyloid in the brain, is the sixth-leading cause of death in the United States. Currently more than 5 million people, mostly seniors, are living with the disease, and by 2050, some 13.8 million people within the U.S. are projected to have Alzheimer's disease.

Alzheimer's is also a particularly costly disease to treat. The Alzheimer's Association estimates that direct treatment costs totaled $214 billion last year, including $36 billion in out-of-pocket expenses.

Source: Alzheimer's Association, Facebook.

What makes Alzheimer's such a difficult disease to treat is that researchers are still relatively in the dark as to why Alzheimer's triggers in the first place, as well as why it affects one person but not the next. There are factors, such as age and family history, which are widely accepted to be higher-risk factors for developing Alzheimer's, but the root cause of the disease remains a mystery.

That's why a new study at the Keck School of Medicine of the University of Southern California holds such promise.

Could mitigating Alzheimer's-associated cognitive decline be simpler than we thought?
According to the seven-author study that was published last week in the journal Neuron, the anti-inflammatory cytokine IL-10 could be responsible for the immune system failing to clear beta amyloid plaques from the brain.

Lead researcher Marie-Victoire Guillot-Sesstier and her team used genetically modified mice models to test what would happen to cognitive function if IL-10 were blocked or reduced. Using genomewide RNA sequencing of the brains of mice, some deficient in IL-10 and others overexpressing IL-10, researchers observed that those mice with low levels of IL-10 performed cognitively better in terms of learning and memory tests. Researchers also note that "the IL-10 signaling pathway was abnormally elevated in Alzheimer's disease patient brains."

The implication here is that drugs targeting the down-regulation or blocking of IL-10 could be the key to restoring an Alzheimer disease patients' immune system to normal and having it rid beta amyloid plaque on its own.

However, the authors also made it clear that further studies would be needed to confirm that IL-10 is indeed a key regulator of beta amyloid plague removal. In addition, there are no guarantees that what's observed in mice models will translate well to human clinical trials.

New pathways are sorely needed
Although it's extremely early in nature, the reason I highlight USC's study works back to the fact that most experimental Alzheimer's disease drugs have failed in mid- or late-stage trials. The blood-brain barrier is difficult to safely breach, making it a challenge for drug developers to explore new pathways to treat this relatively unmet indication.

Source: Alzheimer's Association-Greater Illinois via Flickr.

The good news is that even though IL-10 blockers could be years away from entering clinical studies, a handful of new therapies could be waiting in the wings to mitigate Alzheimer's symptoms, or dare I say even reverse progression of the disease!

Topping the list of experimental treatments is Biogen Idec's (NASDAQ:BIIB) anti-amyloid antibody BIIB037. To give you some indication of how exemplary its phase 1 results were, the company announced that it was skipping mid-stage studies and jumping right into late-stage trials, with a target results release sometime in 2016.

In Biogen Idec's 194-patient phase 1 trial, BIIB037 didn't just slow disease progression. Instead, a cognitive improvement was actually observed in early stage Alzheimer's disease patients, including a dose- and time-dependent reduction in beta amyloid plaques. In plainer terms, this could be the closest medicine we actually have to a cure if it winds up maintaining its effectiveness in phase 3 trials and is ultimately approved by the Food and Drug Administration. Later this year, Biogen Idec has also promised to release the full data set from its phase 1 study.

Source: Eli Lilly.

The other intriguing therapy comes from privately held TauRx Pharmaceuticals. Considering the excitement surrounding its experimental phase 3 drug LMTX, I'd offer my opinion that a public offering could be a smart move if the clinical results work in favor of TauRx.

LMTX is TauRx's second-generation twice-daily oral medication designed to treat mild-to-moderate Alzheimer's disease. LMTX specifically works by targeting misfolded or aggregated Tau proteins, which are commonly associated with cognitive degeneration. It also bears the same active ingredient as previously tested Alzheimer's drug Rember, but bears a considerably safer profile. In phase 2 trials Rember delivered a 90% reduction in the rate of Alzheimer's progression over a two-year period, lending a lot of hope toward LMTX's upcoming results.

Critical data is on the way
In sum, it's great to see Alzheimer's disease getting some much-needed attention. Both Biogen Idec and TauRx are likely going to report critical top-line data for their lead drugs at some point in 2016. Combine this with data due at some point soon from Eli Lilly and its beta-amyloid inhibitor solanezumab, which failed in phase 3 studies but was being examined more closely for efficacy in earlier stages of the disease, and we have some genuine hope for those afflicted with Alzheimer's.

Admittedly, there are still just as many, if not more, questions left to be answered than we have answers for. However, progress is clearly being made. It may only be a matter of time before we have a new standard of care for Alzheimer's patients and a real quality of life improvement.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.