New test to diagnose early stage Alzheimer's disease

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.

Data from 848 adults of all ages has found that brain volume in the default mode network declined in both healthy and pathological aging, but the greatest decline occurred in Alzheimer’s patients and in those who progressed from mild cognitive impairment to Alzheimer’s disease. Reduced brain volumes in these regions were associated with declines in cognitive ability, the presence of Alzheimer’s biomarkers in the cerebrospinal fluid, and with carrying the “Alzheimer’s gene”, the APOE4 allele.

Data from 6257 older adults (aged 55-90) evaluated from 2005-2012 has revealed that concerns about memory should be taken seriously, with subjective complaints associated with a doubled risk of developing mild cognitive impairment or dementia, and subjective complaints supported by a loved one being associated with a fourfold risk. Complaints by a loved one alone were also associated with a doubled risk. Among those with MCI, subjective complaints supported by a loved one were associated with a threefold risk of converting to dementia.

Brain scans of 10 persons with Down syndrome but no dementia, 10 persons with Down syndrome and dementia, and 10 healthy controls, have revealed a linear correlation between cognitive ability and compromised white matter connections in the frontal lobes among those with Down syndrome. Those with higher cognitive ability and motor skill coordination had healthier white matter integrity, and those with additional dementia showed the most deterioration.

Adults with Down Syndrome are known to be at high risk of developing Alzheimer’s after age 40.

Cognitive testing for dementia has a problem in that low scores on some tests may simply reflect a person's weakness in some cognitive areas, or the presence of a relatively benign form of mild cognitive impairment (one that is not going to progress to dementia). A 2008 study found that one of every six healthy adults scored poorly on two or more of 10 tests in a brief cognitive battery. Following this up, the same researchers now show that a more holistic view might separate those who are on the path to dementia from those who are not.