Months backward test: A review of its use in clinical studies

Table 1 A scheme for administering the months backward test

"Hello Mr X, My name is Y. If it is convenient, I would like for you to help me with a simple test to assess your concentration

Can I ask you to say the months of the year from start to finish in their usual order, starting with January?.....

Now, can I get you to say the months again but this time in reverse order starting with December…."

Where a patient becomes “lost” they may require prompting to re- orientate them to the test and if this is required it should be noted, e.g., what were we doing again? How far did you get to? So before October would be?

Table 2 Clinical studies using the months backward test

Ref.	Population and study purpose	Assessment of MBT performance
Halstead[10,28] (1944)	To develop a battery of tests for “senility” in 38 subjects, 20 with recognised dementia	Pass/fail according to capacity to recite months in reverse from December to January
Young et al[20] (1997)	To compare the performance of 522 uninjured high school athletes on three simple mental status tests that are commonly used on the sidelines for the evaluation of concussions	Participants were given 1-min time limits for each test, with passing defined as either 7 consecutive correct iterations or 11 correct with one mistake
Ball et al[8] (1999)	To evaluate the efficacy and reliability of the time to recite the months of the year in reverse order as a simple measure of central processing speed in 120 community-dwelling women, aged 67-94	Timing of MBT performance commenced when the subject starts the sequence and continues regardless of omissions, juxtapositions, or corrections until the sequence is complete or 75 s has elapsed. Those unable to complete the sequence received a score of 75 s
Wildgruber et al[34] (1999)	Comparison of MBT vs MFT in respect of brain activation using fMRI in 18 neurologically normal subjects aged 19-36	Subjects silently recited the MFT and subsequently the MBT as fast as possible and continuously across the whole length of each activation period
Ettlin et al[27] (2000)	Developing a scale (The FLS) to distinguish patients with various Ornagic brain difficulties	MBT rated from 0-2 in respect of both (1) accuracy (1 point for > 1 error of any kind) and (2) 1 point if completion time > 24 s
Lamar et al[22] (2002)	A comparison of the capacity to sustain mental set in participants with AD vs IVD vs a NC	An AcI was calculated using the following algorithm: AcI = {1 - [(false positive + misses)/number of possible correct]} × 100 This algorithm yielded a percentage score such that patients obtaining a score of 100% correctly identified all targets and made no false positive responses or misses
Alderson et al[29] (2003)	To develop a brief scale for assessing cognition in patients with TBI	A 4 point scale was applied where 0 = unable to complete of ≥ 2 errors; 1 = able to complete but with 2 errors; 2 = able to complete but with one error; 3 = completed without error
Marinus et al[9] (2003)	Development of a scale to assess cognition in PD. Eighty-five PD patients and 75 control subjects were assessed with a battery of tests of which the MBT was a significantly discriminating test of attention. Test–retest reliability was assessed in 30 patients after 6 wk	Performance rated on a scale of 0-2 but unclear how these scores were attributed
Rudolph et al[5] (2006)	To determine the extent to which preoperative performance on tests of executive function and memory was associated with delirium after coronary artery bypass graft surgery	Pass/fail according to ability to successfully recite from December back to January
Dubois et al[21] (2007)	To develop consensus amongst an expert group regarding diagnostic procedures for PD dementia	Pass/fail according to ability to successfully recite from December back to January. An unsuccessful performance equated with omission of two or more months, incorrect sequencing of the months, or failure to complete the test within 90 s
Ostberg et al[11] (2008)	To explore the utility of the MBT in diagnosis of cognitive impairment in N = 234 memory clinic attenders with subjective cognitive impairments, mild cognitive impairment and AD	Participants recited the months in reverse chronological order as quickly as possible. Ability to conduct the test accurately and duration to task completion were measured
Shehata et al[14] (2009)	To determine baseline symptom and neurocognitive norms in 260 university athletes with and without concussion histories using the SCAT	Months in reverse order was assessed on a pass/fail basis where a subject passed if they were able to recite the 12 mo in reverse order with no mistakes. The test was considered a fail if any months were in the wrong order or missed
Roca et al[24] (2010)	Comparison of neuropsychological performance in patients with documented frontal lobe lesions (n = 15) vs matched neurologically unimpaired controls	The patient was asked to list the months of the year backwards, starting with December. If subjects made no errors, the score was 2; for one error, the score was 1; otherwise the score was 0
Schneider et al[15] (2010)	Assessing performance on tests of cognition in hockey players aged 9-17 with and without a history of concussion	The MBT was conducted as part of the SCAT: Months in reverse order was assessed on a pass/fail basis where a subject passed if they were able to recite the 12 mo in reverse order with no mistakes
Grober et al[6] (2011)	Investigating for predictors of diabetes control in 169 elderly diabetics	A composite score was constructed with 5 levels based upon animal naming and MBT performance as completed without errors, uncorrected errors or failed test
Östberg et al[19] (2012)	Identification of adult norms and test-retest reliability for durational and response accuracy on the MBT in 216 neurologically intact adults (aged 18-88). A retest was conducted with 40 participants after 3 wk	Participants were instructed to recite the months in backward order as quickly as possible without making any errors. The duration from commencement to cessation was defined as the MB duration score. Any uncorrected sequence error was noted down, and the total number of errors was defined as the MB response accuracy score. Errors were taken to include omissions and transpositions. Repetitions were not scored as errors
Jinguji et al[13] (2012)	To determine baseline scores in cognitive performance domains among 214 high school athletes with no prior history of a concussion	Ability to recite the months of the year in reverse order to January
Ryan et al[16] (2013) and O’Regan et al[17] (2014)	To screen for attention problems in 311 general hospital inpatients for further testing regarding possible delirium and dementia	Pass vs fail according to whether subjects could reach July without major error/with minimal prompting
Tardiff et al[12] (2013)	To identify predictors of cognitive decline in patients with Alzheimer’s dementia	Pass vs fail according to whether subjects could correctly order the months from December to January
Bellelli et al[18] (2014)	To evaluate a new screening tool for delirium (4AT) in 236 elderly medical patients	MBT performance rated as: Achieves 7 mo correctly = 0 Refuses or starts but scores < 7 mo = 1 Untestable = 2

MBT: Months backward test; FLS: Frontal Lobe Score; AD: Alzheimer’s disease; AcI: Accuracy index; IVD: Ischemic vascular dementia; NC: Non-demented control group; TBI: Traumatic brain injuries; PD: Parkinson’s disease; SCAT: Sport concussion assessment tool.

Table 3 Suggested grading of performance on the months backward test

Simple grading:

0 = The subject cannot engage meaningfully with testing procedures

1 = The subject engages but cannot complete the test, even with prompting

2 = The subject completes the test, but with prompting and/or errors

3 = The subject completes the test without error within 30 s (under 65 years old) or 60 s (over 65 years old)

Detailed grading (e.g., for research)

0 The subject does not understand that they are being assessed? i.e., lacking basic awareness

1 The subject understands that they are being assessed

2 The subject understands the “rules” of the test (i.e., can grasp/ comprehend the test)

3 The subject engages with testing procedures, e.g., recite months forward (i.e., focused attention)

4 The subject engages in a sustained manner, i.e., sustained attention

5 The subject successfully shifts to backwards testing, i.e., shift attention

6 The subject can reach July

7 The subject can reach January

8 If the subject makes any errors, they recognise this and/or try to correct the errors

9 The subject completes the test without errors

10 Completion of the test takes less than 90 s/60 s/30 s