Efficacy of Lu AA21004 on Cognitive Dysfunction in Major Depressive Disorder

PDQ is a patient-rated scale designed to subjectively assess cognitive dysfunction, comprising four 5-item subscales: Attention/Concentration, Retrospective Memory, Prospective Memory, and Planning/Organization for a total possible score of 0 to 40. The subscale Attention/Concentration is the sum of items 1, 5, 9, 13, and 17 with a range of 0-20; while the subscale Planning/Organization is the sum of items 4, 8, 12, 16, and 20 with the score range of 0 to 20. The scores of the subscales Attention/Concentration and Planning/Organization were summed. Higher scores reflect greater participant-perceived cognitive dysfunction in the domains identified. A decrease in score represents an improvement in subjective cognitive function in the domains identified. A Mixed Model Repeated Measures (MMRM) model was used with baseline*week, center, week, treatment and week*treatment as factors in the analysis.

The CGI-I assesses the clinician's impression of the subject's state of mental illness improvement and consists of one question for the investigator: "Compared to his condition at the start of the study, how much has this patient changed?" which is rated on a seven-point scale (1=very much improved; 2=much improved; 3=minimally improved; 4=no change relative to baseline; 5=minimally worse; 6= much worse; 7=very much worse). Higher scores indicate greater worsening of illness. Values closest to 1 for this outcome measure indicate the greatest improvement of symptoms. A MMRM model was used with baseline*week, center, week, treatment and week*treatment as factors in the analysis.

The TMT is a two-part cognitive test. TMT-A assesses cognitive processing speed and consists of 25 circles distributed over a sheet of paper. Participants have 4 minutes to connect the circles as quickly as possible, without lifting the pen or pencil from the paper. Tester informs participant immediately whenever they make an error and allows for corrections by participants. Lower scores represent better speed of processing. A decrease in score over the study represents an improvement in speed in processing. An ANCOVA model was used with treatment and center as fixed factors and the baseline value as a covariate.

The TMT is a two-part cognitive test. TMT-B assesses executive functioning and consists of 25 circles distributed over a sheet of paper. Participants have 4 minutes to connect the circles as quickly as possible, without lifting the pen or pencil from the paper. Tester informs participant immediately whenever they make an error and allows for corrections by participants. Lower score for TMT-B represents better executive function. A decrease in score over the study represents an improvement in executive function. An ANCOVA model was used with treatment and center as fixed factors and the Baseline value as a covariate.

The STROOP test assesses the ability to inhibit a prepotent response to reading words while performing a task that requires attention control. It comprises of 2 sheets with 50 words each, up to 50 correct responses for each of the congruent and incongruent Stroop tests. Participants have 4 minutes to name the ink color of each word. Lower time to complete the test indicates better performance. Higher number of correct responses indicates better responses. A decrease in the time to complete the tests and an increase in the number of correct responses both indicate improvement over the course of the study. An ANCOVA model was used with treatment and center as fixed factors and the Baseline value as a covariate.

The GMLT measures executive functioning and spatial problem solving. Participants learn a hidden pathway through a maze of 10 x 10 grid of tiles on a computer touch screen using step-by-step guess, with trial and error feedback after each step. Once the pathway is learned, participants repeat the same pathway four more times. It usually takes 5-6 minutes to administer this test. Lower score equals better performance. A decrease in score over the course of the study indicates improved executive function.

An ANCOVA model was used with treatment and center as fixed factors and the Baseline value as a covariate.

The DT is a computerized test that measures simple reaction time and psychomotor speed. The task requires participants to respond by pressing a "yes" button as soon as an onscreen playing card is turned over and is red, and by pressing a "no" button if the card is not red. It takes 2 minutes to be administered. There is no minimum or maximum scores since it is a time-based assessment. Lower score equals better performance. A decrease in score over the course of the study indicates improved speed of processing and psychomotor function. An ANCOVA model was used with treatment and center as fixed factors and the Baseline value as a covariate.

The IT measured choice reaction time: the participant pressed a "yes" button whenever an onscreen playing card turned face up and was red, or a "no" button if the card was not red. The IT took on average 2 minutes to complete. Lower scores equal better performance. A decrease in score over the course of the study indicates improved visual attention/vigilance. An ANCOVA model was used with treatment and center as fixed factors and the Baseline value as a covariate.

The One-Back test measures the cognitive domain of attention and working memory through yes or no responses to 30 trials. The task requires participants to report when a stimulus item presented serially is the same as an item one step back from the item at hand for a total correct responses 0 to 100. It usually takes 2-3 minutes to be administered. Higher scores equal better performance. An increase in score over the course of the study indicates improved attention/working memory. An ANCOVA model was used with treatment and center as fixed factors and the Baseline value as a covariate.

Improvement of Cognitive Dysfunction is determined using the change from Baseline to Week 8 in the Montgomery-Åsberg Depression Rating Scale (MADRS) Total Score and the Digital Symbol Substitution Test (DSST) total number of correct symbols. The MADRS is a 10-item clinician rated scale to measure overall severity of depressive symptoms (such as apparent sadness, reported sadness, inner tension) rated on a 7-point Likert scale from 0 (symptoms absent) to 6 (severe depression). The DSST assesses relative contributions of speed, memory, executive function and visual scanning. The proportion of direct effect from treatment = DSST difference / (DSST difference + coefficient*MADRS difference).

MADRS is a 10-item clinician rated scale to measure overall severity of depressive symptoms (such as apparent sadness, reported sadness, inner tension) rated on a 7-point Likert scale from 0 (symptoms absent) to 6 (severe depression) with a total possible score range from 0 to 60. Higher scores indicate greater severity of symptoms. A negative change from Baseline indicates improvement.

MADRS is a 10-item clinician rated scale to measure overall severity of depressive symptoms (such as apparent sadness, reported sadness, inner tension) rated on a 7-point Likert scale from 0 (symptoms absent) to 6 (severe depression) with a total possible score range from 0 to 60. Higher scores indicate greater severity of symptoms. MADRS Response was defined as a ≥50% decrease in MADRS Total Score from Baseline.

MADRS is a 10-item clinician rated scale to measure overall severity of depressive symptoms (such as apparent sadness, reported sadness, inner tension) rated on a 7-point Likert scale from 0 (symptoms absent) to 6 (severe depression) with a total possible score range from 0 to 60. Higher scores indicate greater severity of symptoms. MADRS Remission was defined as a MADRS total score ≤10.

The CGI-S assesses the clinician's impression of the subject's current state of mental illness and consists of one question for the investigator: "Considering your total clinical experience with this particular population, how mentally ill is the patient at this time?" which is rated on a seven-point scale (1=normal, not ill at all; 2=borderline mentally ill; 3=mildly ill; 4=moderately ill; 5=markedly ill; 6=severely ill). A MMRM model with baseline*week, center, week, treatment and week*treatment as factors was used for analyses.