What are the serial sevens?

From the Guidelines

Serial sevens is a mental test used to assess attention and concentration, particularly in neurological and psychiatric evaluations, which requires a person to start with the number 100 and repeatedly subtract 7, stating each result aloud. The test is commonly used as part of the Mini-Mental State Examination (MMSE) and other cognitive assessments, such as the Montreal Cognitive Assessment (MoCA) 1. Healthcare providers use this test because serial subtraction requires sustained attention and working memory, making it effective for detecting cognitive impairment, as noted in the Alzheimer's Association clinical practice guideline for the diagnostic evaluation, testing, counseling, and disclosure of suspected Alzheimer's disease and related disorders (DETeCD-ADRD) 1. The difficulty of subtracting 7 (compared to easier numbers like 5 or 3) makes it sensitive to even mild cognitive issues, and patients with dementia, delirium, or other cognitive disorders often struggle with this task 1. Some key points to consider when administering the test include:

• The test requires the patient to start with the number 100 and repeatedly subtract 7, stating each result aloud (100,93,86,79,72,65,58,51,44,37,30,23,16,9,2) 1
• Clinicians typically ask for five consecutive subtractions and note both accuracy and the time taken to complete the task 1
• Alternative versions include counting backward from 100 by 3s or spelling "world" backward for patients with limited mathematical ability 1
• The test can be adapted for telemedicine, with variations of the MMSE and MoCA available for remote administration 1 Overall, serial sevens is a useful tool for assessing cognitive function and detecting potential impairments, and its use is supported by recent clinical practice guidelines 1.

From the Research

Definition and Purpose of Serial Sevens

• The serial sevens test, also known as the Serial Seven Test (SST), is a measure of concentration that involves serial subtraction by seven 2.
• It is frequently used in mental status evaluation for dementia as a measure of concentration 2.
• The test is also used to assess attention and mental concentration 3.

Administration and Validation

• There is no uniform method of administration for the serial sevens test, which has led to concerns about its usefulness 3.
• Research has shown that calculation skill is at least as important as concentration in predicting SST performance 2.
• The test has been found to be weakly associated with other measures of attention, such as backwards spelling of the word "world" 4.
• Standardization and adult norms for the serial sevens test have been established to make it a more effective screening technique 3.

Effectiveness and Limitations

• The serial sevens test has been found to be less effective than other tests, such as recitation of months of the year in reverse order, in evaluating mental status in high school athletes 5.
• The test has been found to lack specificity, with a high failure rate among uninjured high school athletes 5.
• Brief single-domain tests, including the serial sevens test, have been found to offer diagnostic performance for detection of dementia that is close to that of cognitive batteries such as the Mini-Mental State Examination (MMSE) 6.