Memory Tests May Not Properly Diagnose Alzheimer's Disease in Women

A recent study found that verbal memory skill tests may not be an accurate indicator of cognitive impairment in women associated with Alzheimer’s disease.

This occurrence is because women typically perform better on these tests compared with men in the same disease stage, according to the study published by Neurology.

“Women perform better than men on tests of verbal memory throughout life, which may give them a buffer of protection against losing their verbal memory skills in the precursor stages of Alzheimer's disease, known as mild cognitive impairment,” said study author Erin E. Sundermann, PhD. “This is especially important because verbal memory tests are used to diagnose people with Alzheimer's disease and mild cognitive impairment, so women may not be diagnosed until they are further along in the disease.”

Mild cognitive impairment is the initial stage of Alzheimer’s disease and other dementias, and is characterized by minor problems with memory. These patients can experience more difficulties remembering things or thinking.

Another study showed how a novel blood test may be able to detect mild cognitive impairment associated with Alzheimer’s disease by measuring the levels of amyloid-beta 42 peptide in their cerebrospinal fluid. However, it is not possible to predict whether a person will develop Alzheimer’s disease through memory tests, scans, and protein level measurements.

In the current study, researchers analyzed data from 245 patients with Alzheimer’s disease, 672 patients with mild cognitive impairment, and 390 control patients. All patients included were a part of the Alzheimer’s Disease Neuroimaging Initiative.

Patients received verbal memory tests and PET brain scans to determine their brain’s ability to metabolize glucose, which can be an indicator of dysfunction in the cells if metabolism is slowed. The verbal memory test consisted of reading 15 words then repeating them immediately, and then again after 30 minutes. The maximum score was 75, and a score of less than 37 was considered impaired for the immediate recall.

For the delayed recall, patients were considered impaired if they scored less than 8 out of 15 points. Glucose metabolism was measured in the temporal lobe and in the cerebellum on a scale from 1 to 4, with 1 meaning significant brain cell dysfunction.

Researchers found that women with no, mild, or moderate dysfunctional glucose metabolism outperformed men on the memory test. The performance of patients with advanced metabolism dysfunction was similar among men and women.

“These results suggest that women are better able to compensate for underlying changes in the brain with their 'cognitive reserve' until the disease reaches a more advanced stage,” said Dr Sundermann.

The results of the immediate recall test showed that women reached the impaired scores at a lower glucose metabolism rate (2.2) compared with men (3.7), and a glucose metabolism rate of 2.9 for women and 3.7 for men in the delayed recall test was associated with impairment, according to the study.

“If these results are confirmed, adjusting memory tests to account for the differences between men and women may help diagnose Alzheimer's disease earlier in women,” Dr Sundermann concluded.