A new study says that an investigational intervention, which used naturally ocurring antibodies in human blood, has preserved the thinking abilities of a group of mild- to moderate-stage Alzheimer's patients over 18 months and significantly reduced the rate of atrophy (shrinkage) of their brains.
Researchers at the NewYork-Presbyterian Hospital/Weill Cornell Medical Center, conducted the Phase II clinical trial of GAMMAGARD LIQUID and GAMMAGARD S/D Immune Globulin Intravenous (Human) (IGIV) for Alzheimer's disease (AD).
Dr. Norman Relkin found that patients receiving IGIV once or twice a month for 18 months had significantly lower rates of ventricular enlargement and less whole-brain atrophy than control subjects who initially received placebo.
Relkin's findings were based on two independent analyses of brain-imaging data from 20 patients who underwent serial MRI scans during the Phase II study of IGIV for AD.
"Past AD studies that used MRI measures found no change or an accelerated rate of brain shrinkage after investigational treatments. To the best of my knowledge, this is the first trial in which long-term clinical benefits in Alzheimer's patients were accompanied by objective signs of reduced brain degeneration," said Relkin.
A typical AD patient's brain shrinks three to four times faster than a healthy older adult's as a consequence of accelerated brain cell death.
This shrinkage of brain tissue causes the fluid-filled ventricles at the center of the brain to enlarge at a faster than normal rate.
Changes in the size of the brain and ventricles can be measured accurately by analysing results from two or more MRI scans obtained at an interval of at least several months apart.
The unprecedented reductions in these measures after IGIV reported by the researchers could indicate that IGIV exerts a disease-modifying effect that the current generation of approved AD treatments lack.
Relkin also found that rates of brain shrinkage after IGIV intervention were independent of the subject's age, gender and brain volume at the start of the study but strongly correlated with dose of IGIV and the clinical outcomes after 18 months of intervention.
The team also found that AD patients who responded best to IGIV did not measurably decline over 18 months, and had an average rate of brain shrinkage and average rate of ventricular enlargement comparable to the rate previously reported in normal elderly individuals.
"A dose-related effect of an Alzheimer's intervention on brain ventricular enlargement has never been seen before, and it suggests that IGIV may, indeed, be sparing brain tissue," said Dr. James Brewer, a neurologist and assistant professor of neurology at the University of California at San Diego.
Brewer independently analysed the MRIs from the Phase II IGIV study, and his findings closely matched those obtained by Dr. Dana Moore, a postdoctoral fellow working with Dr. Relkin at Weill Cornell.
"I am particularly looking forward to examining the Phase III data when that study is completed. Since it involves a considerably larger group of patients, it will permit us to obtain more detailed measures of atrophy in the brain regions specifically vulnerable to Alzheimer's disease," said Brewer.
The study has been presented at the American Academy of Neurology (AAN) meeting in Toronto.