MCI: Should memory tests score males and females differently?
17 October, 2019
A recent study found that scoring verbal memory tests according to sex can alter who receives a diagnosis of mild cognitive impairment (MCI) by as much as 20%.
Evidence shows that females tend to have better verbal memory than males, and yet, tests that assess cognitive ability do not reflect this.
In the new study, the researchers scored memory tests using different norms and thresholds, or cut-off scores, for males and females.
They found that using sex-specific scores led to 10% more females and 10% fewer males receiving a diagnosis of MCI compared with scores that used averages.
The team suggests that should further studies validate the findings, they could change the way that doctors diagnose males and females for dementia.
"If these results are confirmed, they have vital implications," says first study author Erin E. Sundermann, Ph.D., a scientist at the University of California, San Diego.
She explains that one of the consequences of identifying people as having no memory difficulties when they actually have MCI is that they do not start treatment when they should. This can also mean that they and their families do not begin planning future care and putting affairs in order.
Conversely, inaccurately diagnosing someone with MCI when they do not have it means that they take unnecessary drugs, and they and their families experience undue stress.
MCI does not always precede dementia
MCI affects around 15-20 percent of people aged 65 and older.
People with MCI have a small but measurable reduction in their memory and thinking ability. The loss is not enough to stop them from being able to take care of themselves and carry out everyday tasks.
Typical symptoms of MCI include losing the thread of a conversation and forgetting important appointments. Problems with reasoning and reaching decisions can also occur.
While MCI commonly precedes dementia, having the condition does not necessarily mean that dementia will follow.
Doctors and scientists speak of two types of MCI: amnestic and nonamnestic. Amnestic MCI (aMCI) mostly impairs memory and is the subject of the new study.
Nonamnestic MCI mostly affects the other mental skills, such as visual perception, making sound decisions, and judging the order of steps in a complicated task.
The recent findings follow those of a 2016 study, which revealed that females show better verbal memory in aMCI than males. This happens even though their brains' ability to metabolize glucose might have similar impairments. Problems with glucose metabolism in the brain is a feature of Alzheimer's disease, which is the most common cause of dementia.
"This [earlier finding] is especially important because verbal memory tests are used to diagnose people with Alzheimer's disease and [MCI], so women may not be diagnosed until they are further along in the disease," notes Sundermann, who was also first author of the earlier study.