Alzheimer's disease consists of three subtypes

Alzheimer's disease, long thought to be a single disease, actually consists of three distinct subtypes, says a study.

"Because the presentation varies from person to person, there has been suspicion for years that Alzheimer's represents more than one illness," said the study's author Dale Bredesen, professor of neurology at University of California, Los Angeles, US.

"When laboratory tests go beyond the usual tests, we find these three distinct subtypes

One of the three variations which affects relatively young individuals appears to be fundamentally a different condition than the other two, Bredesen noted.

The finding could lead to more highly targeted research and, eventually, new treatments for the debilitating neurological disorder, which robs people of their memories.

"The important implications of this are that the optimal treatment may be different for each group, there may be different causes, and, for future clinical trials, it may be helpful to study specific groups separately," Bredesen said.

The subtype cortical affects relatively young individuals and appears more widely distributed across the brain than the other subtypes of Alzheimer's, the study said.

It typically does not seem to cause memory loss at first, but people with this subtype of the disease tend to lose language skills.

It is often misdiagnosed, typically affects people who do not have an Alzheimer's-related gene and is associated with a significant zinc deficiency.

The other two subtypes are inflammatory and non-inflammatory. In the inflammatory subtype, markers such as C-reactive protein and serum albumin to globulin ratios are increased and in non-inflammatory, these markers are not increased but other metabolic abnormalities are present.

The two-year study involved metabolic testing of 50 people.

The findings appeared in the journal Aging.