Table 1 Oral cognitive assesments

Information processing speed

 SDMT

This test is similar to the m-Path smartphone test. However, now, the participant is asked to verbally match the number representing the symbol given as depicted in the legend provided on the top of the page. The researcher writes down the answers on a separate page. The first 10 trials are used for familiarization, then the participant is given 90 s to verbally match as many numbers to symbols as possible. The final score is obtained by subtracting the number of errors from the number of items completed within the given timeframe [34]. To minimize learning effects, three different versions of this test will be used

Verbal fluency

 COWAT

For this test participants are asked three times to name as many words starting with a specific letter in one minute time. Words cannot be named more than once and non-existing words are not counted. In addition, names of persons and numbers are also not allowed. There are three versions of this test (DAT, KOM, PGR) in the Dutch language. The total score is the sum of the number of words named for each of the three letters [34, 35]

Attention/concentration

 Digit Span Forward

Participants will be given a series of numbers, starting with 2 numbers and progressing to 9 numbers, read by an assessor. Participants will be asked to repeat the numbers in the same order. They get two trials before progressing to a larger series of numbers. When both series are answered incorrectly, the test is ended. The total score is the number of correctly answered series [34]. There are two versions of this test available at our institution

Executive functions

 Digit Span Backward

This version of the digit span adds a working memory component to the test when compared to the forward digit span. Participants will be given a series of numbers, starting with 2 numbers and progressing to 9 numbers, read by an assessor. Participants will be asked to repeat the numbers backwards. They get two trials before progressing to a larger series of numbers. When both series are answered incorrectly, the test is ended. The total score is the number of correctly answered series [34]. There are two versions of this test available at our institution

 TMT A & B

This test assesses switching ability. This test encompasses two parts. In trial A, the participant verbally count from 1 to 25 as quickly as possible. In trial B, the participant will be instructed to verbally alternate between numbers and letters of the alphabet until 13. The time difference between trial A and B will be recorded. This test lasts approximately 3 min [34, 36]

 Stroop test

This test assesses cognitive inhibition, but also attention and processing speed. This test consists of three lists that the participant must read out loud; the first list has the names of colors printed in black ink, the second list with the colors printed in colored ink, and the final list having the name of colors printed in incongruent colored ink (e.g., the word red is printed in blue ink). The time to complete second list, third list, as well as the time difference between these latter two lists will be recorded. The test takes approximately 5 min. There is one version of this test available [34, 37]

Memory

 15 word test (RAVLT)

The 15 word test is the RAVLT. This test consists of a list of 15 words that is read to the participant by an assessor. After reading, the participant must try to recall as many words as they can. This read and recall process is repeated an additional four times. A distractor list (second list) is presented with a recall attempt, followed by a timed recall of the first list. The timed recall measures the participant’s ability to recall information despite the intervening list. After 10 min, the participant performs another timed recall of the first list of words. Afterwards the participant is given a recognition task where they identify the 15 words from the initial list from a paragraph containing 30 underlined words. This final trial distinguishes memory storage from inefficient recall [34]. There are two versions of this test available at our institution