Conversations as a Means to Delay the Onset of Alzheimer's Disease (conversation)

Mini Mental State Examination assess global cognitive function. Possible score ranges from 0 to 30. In this study, score ranges from 24 to 30 (those with MMSE <24 at baseline were excluded according to the study exclusion criteria). Changes in test results among the experimental group are compared with changes among the control group using linear regression models. (no drop out reported and therefore no need to use mixed effects models or MMRM) Higher values (post-pre) indicate that decline was less or test score improved more.

Verbal fluency Animals test is a neuropsychological test. In the test, participants have to produce as many words as possible from a category of animals within 60 seconds. Total score ranges from 0 to 70. Changes in test results among the experimental group are compared with changes among the control group using linear regression models. (no drop out reported and therefore no need to use mixed effects models or MMRM). Higher values mean decline is less or score improve at post-study assessment.

Verbal fluency letter test is a neuropsychological test. In the test, participants have to produce as many words as possible which start with a letter F, A and S (3 separate test for each letter) within 60 seconds. Each test score ranges from 0 to 40. Total of 3 tests scores (F, A and S) ranges from 0 to 120. Changes in test results among the experimental group are compared with changes among the control group using linear regression models. (no drop out reported and therefore no need to use mixed effects models or MMRM) Higher values mean decline is less or test scores improved at post-study assessment.

Consortium to Establish a Registry for Alzheimer's Disease Word List Immediate Recall (CERAD Word List Immediate Recall) total score counts number of words correctly recalled over 3 trials (with each trial having 10 words), and ranges from 0 to 30. Pre-post changes in test results among the experimental group were compared with pre-post changes among the control group using linear regression models. (no drop out reported and therefore no need to use mixed effects models or MMRM)

Consortium to Establish a Registry for Alzheimer's Disease Word List Delayed Recall (CERAD Word List Delayed Recall) total score counts number of words correctly recalled in one trial (10 words) and it ranges from 0 to 10. Pre-post trial changes in test results among the experimental group was compared with pre-post changes among the control group using linear regression models. (no drop out reported and therefore no need to use mixed effects models or MMRM)

In Trail Making test A, the subject is instructed to connect a set of 25 dots as quickly as possible while still maintaining accuracy within 150 seconds. Time to complete is used here. Pre-post trial changes in test results among the experimental group are compared with pre-post changes among the control group using linear regression models. (no drop out reported and therefore no need to use mixed effects models or MMRM). Larger changes mean subjects got slower to complete the test at the post-trial assessment. Negative changes indicates subjects completed the test faster at the post-trial assessment.

In Trail Making test B, the subject is instructed to connect a set of 25 dots as quickly as possible while still maintaining accuracy within 300 seconds. In Test B, the circles include both numbers (1 - 13) and letters (A - L). Time to complete is used here. Pre-post trial changes in test results among the experimental group are compared with pre-post changes among the control group using linear regression models. (no drop out reported and therefore no need to use mixed effects models or MMRM). Larger changes mean subjects got slower to complete the test at the post-trial assessment. Negative changes indicates subjects completed the test faster at the post-trial assessment.

In the Stroop test, subjects are required to read three different pages of stimuli in a designated time as quickly as possible. First, the individual is asked to name a series of colored squares (Color Naming task, Stroop Test A). Second, the individual is asked to read color words (Word Reading task, Stroop Test B). The final task is the Color-Word Naming task (Stroop Test C) on which the individual is shown the names of colors printed in conflicting ink colors (e.g., the word "red" in blue ink) and is asked to name the color of the ink rather than the word. Each test (A, B, C) is administered for 45 seconds. The number of words correctly named for the Stroop Test C was used here. The maximum score of this test is 100 (range: 0 - 100). The higher score indicates better functions. The changes (post-study - baseline test scores) among the experimental group are compared with those among the control group. The higher change scores mean improved function.

In detection test, the on-screen instructions ask: "Has the card turned over?". A playing card is presented face down in the center of the screen. The card flips over so it is face up. As soon as the card flips over the participant must press "Yes". The participant is encouraged to work as quickly as they can and be as accurate as possible.Speed of performance (mean of the log10 transformed reaction times for correct responses) is used here. Pre-post trial changes in test results among the experimental group were compared with pre-post changes among the control group using linear regression models. (no drop out reported and therefore no need to use mixed effects models or MMRM). Larger changes mean subjects got slower in reaction at the post-trial assessment. Negative changes indicates subjects got faster in reaction at the post-trial assessment.

In this test, the on-screen instructions ask: "Is the previous card the same?". A playing card is presented face up in the center of the screen. The participant must decide whether the card is the same as the previous card. If the card is the same the participant should press "Yes", and if it is not the same the participant should press "No". The participant is encouraged to work as quickly as they can and be as accurate as possible. Accuracy of performance (arcsine transformation of the square root of the proportion of correct responses) is reported here. Pre-post trial changes in test results among the experimental group will be compared with pre-post changes among the control group using linear regression models. (no drop out reported and therefore no need to use mixed effects models or MMRM). Larger changes mean the score improved at the post trial assessment.

In this test, the on-screen instructions ask: "Is the card the same as that shown two cards ago?". A playing card is presented face up in the center of the screen. The participant must decide whether the card is the same as the card shown two cards previously. If the card is the same the participant should press "Yes", and if it is not the same the participant should press "No". The participant is encouraged to work as quickly as they can and be as accurate as possible. Accuracy of performance (arcsine transformation of the square root of the proportion of correct responses) is reported here. Pre-post trial changes in test results among the experimental group will be compared with pre-post changes among the control group using linear regression models. (no drop out reported and therefore no need to use mixed effects models or MMRM)

Computer Assessment of Mild Cognitive Assessment (CAMCI) is a battery of computerized tasks to assess cognitive performance, developed by the Psychology Software Tools. The software provides standardized score (z-score) based on subject's age, sex and education.* The Z-score indicates the number of standard deviations away from the mean. A Z-score of 0 is equal to the mean. Higher Z-score means better cognitive function. A positive change in Z-scores here indicates a favorable outcome. Total score (global cognitive function measure) is used here. Pre-post trial changes in test results among the experimental group are compared with pre-post changes among the control group using linear regression models. (no drop out reported and therefore no need to use mixed effects models or MMRM) *: Saxton J, Morrow L, Eschman A, Archer G, Luther J, Zuccolotto A. Computer assessment of mild cognitive impairment. Postgrad Med. 2009;121(2):177-85.