SAN FRANCISCO, CA — It may be time to wipe the dust off an old screening test that measures problem-solving, judgment, and reasoning skills, according to investigators in California.
In a head-to-head study, the older test, called the Trail Making Test B, beat out the standard Mini-Mental State Examination (MMSE) in predicting which people would have trouble doing everything from dressing and washing to shopping and preparing meals over the next six years.
“If we can identify patients who are likely to suffer functional decline in activities of daily living down the road, we may be able to intervene with physical therapy and other treatments,” said Julene K. Johnson, PhD, Assistant Professor of Neurology in the Memory and Aging Center at the University of California-San Francisco School of Medicine. “We could step up interventions to improve strength and balance, for example.”
COMPARISON OF SCREENING TESTS
Dr. Johnson said the objective of the study was to determine which of two screening tools – the MMSE, which measures global cognition, or the Trail Making Test B, which measures executive function – would better predict a patient's ability to perform activities of daily living over time.
“Our hypothesis,” she said, ''was that the MMSE might not be a good predictor of who will have trouble with activities of daily living because it does not take into account many different cognitive variables, such as planning.
“It's not very sensitive – it measures a lot of areas in a superficial way. For example, the test asks individuals to remember three words in a few minutes versus measuring memory over 10 minutes or more.”
The Trail Making Test B, on the other hand, measures skills such as planning and shifting between two tasks that involve the frontal cortex, Dr. Johnson said.
Trail Making Test B, which requires “you to name numbers and letters in order in an alternate pattern, such as 2a, 3b, etc.,” takes fewer than two minutes to administer, and no training or experience is necessary, she said.
The prospective study, presented here at the AAN Annual Meeting and being submitted to a journal for publication, enrolled 7,716 elderly women, with a mean age of 73.3 years.
At baseline, 12.4 percent of women had poor baseline executive function, defined as scores greater than one standard deviation below the mean on the Trail Making Test B; and 5 percent of women had poor global cognition, defined as a score below 23 on the 27-point modified MMSE. Also, 3.2 percent of women had poor scores on both tests, while 79.4 percent had impairments on neither test.
The study showed that at baseline, women with low scores only on the Trail Making Test B had more trouble with at least one activity of daily living (36.3 percent) – walking, dressing, getting in and out of bed – or an instrumental activity of daily living (48.5 percent) – shopping, preparing meals, doing heavy housework – compared with women only on the modified MMSE, Dr. Johnson said.
More importantly, at six-year follow-up, women with poor scores on the Trail Making Test B were 40 percent more likely to show a worsening in ability to perform activities of daily living, compared with women with no impairment on either test. This was significant even after adjustment for medical comorbidities, age, education, and baseline activities of daily living, she said.
Similarly, women with poor scores on the Trail Making Test B were 20 percent more likely to show a worsening in ability to perform instrumental activities of daily living, compared with women with no impairment on either test. Again, “this was significant after adjustments,” Dr. Johnson said.
In contrast, women with impairment only on the modified MMSE were not at significantly increased risk for developing a worsening in ability to perform either activities of daily living or instrumental activities of daily living, she reported.
Deterioration in the ability to perform activities of daily living is common in non-demented elderly persons, she said, and carries a host of consequences: worsened quality of life, high health care costs, and even increased mortality.
The bottom line: The modified MMSE is not a powerful test for predicting decline in activities of daily living over time, Dr. Johnson said.
Physicians should consider performing the brief Trail Making Test B of executive function when screening non-demented elderly individuals, said Dr. Johnson, adding that she would be surprised if even 5 percent of physicians currently employ the test in their practice. “We hope this work will help change that.”
Commenting on the study, Claudia H. Kawas, MD, Professor of Neurology and Neurobiology and Behavior at the University of California-Irvine, agreed the Trail Making Test B should be part of the battery of tests given to patients when screening for dementia.
“Of all the tests that measure dementia, Trail Making Test B is probably the one that goes bad first,” she said. The reason: It measures frontal lobe abilities such as attention and planning – the very skills demented individuals are thought to lose early on in the course of their disease, she said.
“Measuring frontal lobe abilities is an important part of measuring global cognition and one we don't do particularly well,” she said. “Over the long run, it's very important for predicting how well one will do in life.”
The closest the MMSE comes to measuring attention is asking people to spell the word “world” backwards, Dr. Kawas said. “So that's not a very sensitive measure.”
Another problem with the MMSE is that its scoring system does not distinguish between being “really impaired” and “modestly impaired,” she said.
That said, do not throw the baby out with the bathwater, Dr. Kawas stressed. “While Trails is a good test, it measures only one area of our cognitive abilities. The Mini-Mental is a much more global measurement of cognition.”
Researchers still do not know for sure which of the tests best predicts cognitive and other functions over the long run, said Dr. Kawas, who is studying a group of individuals whose average age is 90 years in an attempt to help answer that question in the very elderly. “And until we know that answer, we really can't say which test should be given,” she said.
ARTICLE IN BRIEF
✓ A new study found that the Trail Making Test B was more effective than the Mini-Mental State Examination in predicting which people would have trouble doing everything from dressing and washing to shopping and preparing meals over the next six years.