Primary care doctors screen for signs of dementia in older patients using quick mental-ability tests called brief cognitive assessments. The problem is, the results aren’t always reliable, according to a new study. That doesn’t mean that you or a loved one should skip these assessments, but it’s important to put their value in perspective.

Background: Tests such as the Mini-Mental State Examination (MMSE), the Memory Impairment Screen (MIS) and animal naming (AN) aren’t meant to diagnose dementia, but rather to help primary care doctors decide which patients need a referral for a full dementia exam, which typically is done at a memory clinic or memory center where a team of mental health providers work together to make a diagnosis. That’s the gold standard for diagnosing the condition. It’s a three-to-four-hour assessment that includes a neurological evaluation, psychological testing, DNA sampling, blood testing and interviews with an “informant,” medical jargon for a family member or significant other who is able to provide background information.

When the quick tests miss dementia (false negative), needed diagnosis and treatment are delayed. When they falsely suggest dementia (false positive), a patient may be put through a battery of unnecessary tests and emotional trauma.

The study: To test the accuracy of the three tests, researchers gave them to 824 older adults (average age 82) who had already been diagnosed with dementia following a full dementia exam.

MMSE misclassified 21% of patients and tended to miss dementia in subjects with higher education levels.

MIS misclassified 16% of patients and tended to miss dementia in people with depression, which is common in older people.

AN misclassified 14% of patients and tended to overidentify dementia in people living in nursing homes.

The researchers also found something that can improve the accuracy of these tests…getting key information from a loved one, whether it’s a spouse, family member or close friend, at the same time. Someone who knows the patient well is likely to have noticed any decline in his/her memory, thinking ability and ability to manage daily tasks. In fact, having such a person at an initial cognitive checkup actually is recommended by clinical guidelines. It doesn’t always happen…but it should.

Remember that you’re entitled to a brief assessment as part of the free annual wellness checkup available through Medicare/Medicaid. Don’t forgo the test—just bring a friend to help ensure proper results.

On the horizon: The researchers are testing a new dementia-screening program that takes into account the weaknesses of current tests and has a more personalized approach that combines test scores with patient characteristics.