(NEW YORK) -- Jason Marder watched the inevitable decline of his younger brother, who died of Alzheimer's disease at the age of 50. Then, just after his 60th birthday, he too began to exhibit subtle, early symptoms -- forgetfulness and difficulty focusing on conversations.
The memory loss progressed, and in 2004, Marder got the dreaded diagnosis: Alzheimer's, a disease that affects 5.1 million Americans.
But today, eight years after his diagnosis, Marder isn't any worse off. He has shown no further memory loss and has remained stable.
Marder credits intravenous immunoglobulin, or IViG, therapy and a clinical trial that is swirling in controversy this week after an announcement of study results by the Alzheimer's Association International Conference 2012 in Vancouver.
Some doctors hailed the therapy as "exciting," something that could potentially stabilize the disease, while others said the research is inconclusive and the study -- with only 16 subjects -- was too small.
Nonetheless, today Marder, now retired from working in apparel, continues his independent lifestyle, playing tennis and biking in his native New York City.
"Things are going really nicely. I can't complain," said Marder, now 70. "I don't feel any going backwards."
For the past five years, Marder has been part of a clinical trial with Dr. Norman R. Relkin, director of the Memory Disorders Program at New York-Presbyterian/Weill Cornell Medical Center.
Relkin presented data that found, overall, that 11 study participants who received the immunotherapy Gammagard (IViG) for three full years showed improvements in cognition, memory, daily functioning and mood.
"We are seeing encouraging results," Relkin told ABC News. And despite negative publicity, "I don't want people to give up hope for symptomatic treatment of the disease".
Intravenous immunoglobulin is a mixture that contains molecules pooled from plasma, a component of human blood. It is used to treat various autoimmune, infectious and idiopathic diseases, and its supply is therefore limited.
IViG works by using the body's natural defense or immune system and anti-amyloid antibodies. A protein called beta amyloid accumulates in the brain of those who have Alzheimer's.
"We don't know exactly what it targets, but we do know it contains all antibodies that the body produces," said Relkin. "It alters the function of the immune system and decreases inflammation in the brain".
He said that his research team found the rate of brain shrinkage had slowed and the study had "exceeded criteria" to go forward with a phase III trial.
Copyright 2012 ABC News Radio