It has been 75 years since baseball icon Lou Gehrig declared himself the "luckiest man on the face of the earth," despite a diagnosis at age 35 of amyotrophic lateral sclerosis, a disease with no cure.

In the years since, polio has been virtually eradicated. Chemotherapy has made numerous cancers into curable illnesses. Chemically synthesized insulin treats diabetes. AIDS is kept in check with protease inhibitors. In those 75 years, ALS, the disease that often bears Gehrig's name, has taken the lives of 375,000 Americans, including Gehrig's life at age 37.

In those 75 years, one drug has received FDA approval in the treatment of ALS. That was in 1995.

That drug, riluzole, extends the life expectancy of patients by two to three months. Half of the 5,600 Americans diagnosed with ALS each year will die within three years.

"It's an awful disorder," said neurologist Ghazala Hayat.

The neurodegenerative disease attacks motor neurons in the brain and spinal cord, progressively weakening the body. Muscles twitch and cramp. Speech becomes thick and difficult to understand. Swallowing and walking become arduous, then impossible. Eventually, muscles that control breathing are affected.

The lack of a breakthrough belies the amount of research going on. So far, 20 genes have been identified as linked to ALS, and multiple drug trials are underway. "Each drug, even if it's a failure, shows us a pathway," said Hayat, who runs an ALS clinic at St. Louis University.

SLU's clinic is one of about 35 in the country to offer specialized, multidisciplined services to patients with ALS. More than a dozen practitioners, including neurologists, social workers, dietitians and therapists, work together to design a treatment plan.

For Dave Larson of Sunset Hills, Mo., slurred speech and issues with swallowing first tipped him off that something was wrong. "But we would never have guessed ALS," said Ann Larson, his wife of 18 years. "You put symptoms into WebMD, and about eight [possible causes] come up."

Their lives have revolved around the disease since it was diagnosed in January 2013. Larson, 49, quit his job in publishing; his wife stopped working to care for him.

He has a feeding tube but still tries to eat soft foods. He eats and drinks only when someone else is with him, in case he aspirates. It is an exhausting disease, marked by constant discomfort if not outright pain.

He was "fired" from occupational therapy — as his wife jokingly puts it — when he stopped improving. But twice a week, a massage therapist comes to work his muscles.

But Larson is determined to hold onto whatever independence he can for as long as possible. "My motto is, if you don't use it, it will die faster," he said.

With that in mind, the Larsons traveled to Ohio in June to have a diaphragmatic pacing device implanted in his abdomen. The surgery, performed at University Hospitals of Cleveland at Case Western, involves implanting electrodes into the diaphragm to help with breathing.

But ALS is unrelenting. "You give up a little more independence each day," Larson said.

In the 75 years since the Yankees' Iron Horse got his "bad break," nothing has been found to halt the progress of the disease. With about 30,000 Americans estimated to have ALS, it is considered an "orphan disease." That means little financial incentive exists for research and development. Researchers have identified genes linked to the disease; drug and stem cell trials are underway, though no one seems to be closing in on a cure. Yet.

"It's frustrating," Hayat said. "But people don't give up. These patients teach me what perseverance is. They teach you what it is to fight every day."