The Stages of Objective Memory Impairment (SOMI) test, developed by researchers at Albert Einstein College of Medicine, in New York City, could help identify people in the very first stages of Alzheimer's disease (AD).
"In clinical trials, SOMI stages can be used for prioritizing enrollment of persons likely to have AD pathology," perhaps without the need for expensive or invasive tests, Dr. Ellen Grober of the Department of Neurology at Einstein told Reuters Health by email.
The SOMI system is based on the Free and Cued Selective Reminding Test (FCSRT), which was also developed by Einstein researchers.
"During the past 30 years, the FCSRT has been used internationally in longitudinal studies of aging and dementia as well as in clinical trials for AD. Because the FCSRT is an established tool in the neuropsychological toolbox, it has been widely used in primary-care settings as well. In research settings, FCSRT scores are the most effective predictors of cognitive decline in preclinical AD studies," Dr. Grober said.
SOMI made its debut about three years ago and was designed based on extensive literature linking FCSRT scores to AD biomarkers and future dementia, she explained.
The test defines five sequential stages of memory impairment in predementia AD continuum, ranging from SOMI-0 (no memory impairment) to SOMI-4 (memory impairment compatible with dementia).
Early on, people have difficulty retrieving memories they were able to store in their brains. Memory storage problems occur later when people can no longer store memories in their brains. SOMI can distinguish between the two types.
The SOMI test was used to screen 4,484 older adults for the Anti-Amyloid Treatment in Asymptomatic Alzheimer's (A4) study. Participants also underwent positron-emission tomography (PET) brain scans to detect beta-amyloid.
Half had no memory impairment; the other half had retrieval deficits, storage deficits or both.
The researchers found that people who tested in the third and fourth SOMI stages had a higher beta-amyloid burden in their brains than peers in the lower SOMI stages.
At SOMI stage 0, 30% of people had beta-amyloid plaque, compared to 31% at SOMI stage 1, 35% at stage 2, 40% at stage 3 and 44% at stage 4.
Higher SOMI correlated significantly with lower volume in the hippocampus and other areas of the brain associated with AD pathology, the researchers report in Neurology.
"In addition to having a score on the FCSRT, SOMI provides the clinician with a classification scheme for ranking the severity of memory impairment. This is more similar to how clinicians think about diagnoses," Dr. Grober told Reuters Health.
"SOMI classification also permits clinicians to more easily see when their patient moves from one stage to the next and to know clearly if a change in score has clinical importance. This format may also make it easier for the clinician to provide an explanation to the patient that is readily understandable. Follow-up of memory complaints in the clinical setting would depend on SOMI stage," Dr. Grober said.
She emphasized that "a poor score on the test does not mean that the person has AD and so the patient should not interpret the test results as a definitive diagnosis one way or another."
"The patient should be told this before taking the FCSRT, that the test does not provide a diagnosis of AD or dementia. It provides the doctor validated usable information about the patient's memory problem that led to the testing in the first place. It also guides both parties as to what type of additional evaluations and follow-up seems appropriate," Dr. Grober said.
SOURCE: https://bit.ly/3tgOqUP Neurology, online February 23, 2022.
By Megan Brooks
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