New test to diagnose early stage Alzheimer's disease

Analysis of 1,821 Alzheimer’s brains has found that 11% of them actually suffered from a variant called hippocampal sparing Alzheimer’s. This subtype has been neither well recognized nor treated appropriately, but is now revealed to be relatively common.

Initial findings from an analysis of cerebrospinal fluid taken between 1995 and 2005 from 265 middle-aged healthy volunteers, of whom 75% had a close family member with Alzheimer’s disease, has found that the ratios of phosphorylated tau and amyloid-beta could predict mild cognitive impairment more than five years before symptom onset — the more tau and less amyloid-beta, the more likely MCI will develop. The rate of change in the ratio over time was also predictive — the more rapidly the ratio of tau to amyloid-beta went up, the more likely the eventual development of MCI.

Comparison of the EEGs of 27 healthy older adults, 27 individuals with mild Alzheimer's and 22 individuals with moderate cases of Alzheimer’s, has found statistically significant differences across the three groups, using an algorithm that dissects brain waves of varying frequencies.

A pilot study involving 94 older adults, of whom 18 had Alzheimer’s, 24 had MCI, 26 other dementias, and 26 were healthy controls, has found those with Alzheimer’s were significantly less able to detect the smell of peanut butter. Peanut butter was chosen because of its purity and accessibility (not because there's something special about its smell!).

A five-year study involving 525 older adults (70+) found 46 had Alzheimer’s or aMCI and a further 28 went on to develop the conditions. The blood levels of 10 specific lipids predicted with more than 90% accuracy whether an individual would go on to develop either Alzheimer’s or aMCI within 2-3 years. The researchers speculate that the lower lipid levels could be an early indication that brain cells are beginning to lose their integrity and break down.

New research supports the classification system for preclinical Alzheimer’s proposed two years ago. The classification system divides preclinical Alzheimer's into three stages:

Stage 1: Levels of amyloid beta begin to decrease in the spinal fluid. This indicates that the substance is beginning to form plaques in the brain.

Stage 2: Levels of tau protein start to increase in the spinal fluid, indicating that brain cells are beginning to die. Amyloid beta levels are still abnormal and may continue to fall.

Analysis of mitochondrial DNA (mtDNA) in the cerebrospinal fluid has found that both symptomatic Alzheimer’s patients and asymptomatic patients at risk of Alzheimer’s showed a significant decrease in levels of circulating cell-free mtDNA in the CSF. Patients with frontotemporal dementia did not display this.

A French study has predicted with 90% accuracy which patients with mild cognitive impairment would receive a clinical diagnosis of Alzheimer's disease within the following two years. The best neurological predictors were cortical thickness in two brain regions (the right anterior cingulate and middle frontal gyri), and the best cognitive predictors were deficits in both free recall and recognition episodic memory. Combining these measures achieved the highest accuracy.