A new study has suggested that treating Alzheimer’s disease as six separate conditions could help forge the way for more personalized and effective treatments.
The research, published in the recent issue of Molecular Psychiatry, focused on 4,050 people with late-onset Alzheimer’s disease, splitting them into six groups based on their cognitive functioning at the time they were diagnosed.
Patients in the six groups — where the mean age was 80 and 61 percent were female — were given cognitive scores in four areas: memory, executive functioning, language, and visuospatial functioning.
The researchers found that the largest patient group had similar scores in all four areas but there was considerable variation in the other groups. For instance, the second-largest group had substantially lower memory scores than their other scores, meaning this particular sub-group showed greater memory impairment than the other Alzheimer’s patients. Smaller sub-groups showed greater deterioration in other domains such as language and visuospatial functioning.
The study also used genetic data to find out if there were biological differences between the sub-groups. In one striking discovery, researchers found 33 locations throughout the genome were associated very strongly with one of the subgroups. They also found a particularly strong relationship between a particular variant of the APOE gene and Alzheimer’s risk for the memory loss sub-group.
“The implications are exciting,” said Paul Crane, professor of medicine at the University of Washington School of Medicine and one of the study’s authors. “We have found substantial biological differences among cognitively defined subgroups of Alzheimer’s patients.”
The research team — which involved 19 researchers from institutions including Boston University School of Medicine, the VA Puget Sound Health Care System and Indiana University School of Medicine — hope their findings are a significant step towards more accurately classifying different types of Alzheimer’s patients and creating more targeted treatments.
“Alzheimer’s, like breast cancer, is not one disease,” said lead author Shubhabrata Mukherjee, research assistant professor of medicine at the University of Washington School of Medicine. “I think a good drug might fail in a clinical trial because not all the subjects have the same kind of Alzheimer’s.”
“This study is not the end, it’s a start,” he added.