ROS, MAP, MARS, Clinical Core, LATC
Cogn_global is the main variable for overall (i.e. global) cognitive function. This variable replaces GLOBCOG.
Raw scores from a battery of cognitive tests were converted to Z scores and averaged to yield a global cognitive function summary. Mean and standard deviation at baseline were used to compute the z-scores. Z-score has mean 0 and standard deviation of 1. Each z-score corresponds to a point in a normal distribution. z-score describes how much a point deviates from a mean or specific point. A negative z-score simply means that someone has an overall score that is lower than the average of the entire cohort at baseline.
The following 19 tests are used to compute the global cognitive function score
|test score||z-score||cognitive test||calculated domain|
|cts_wli||z_WLI||word list||episodic memory (cogn_ep)|
|cts_wlii||z_WLII||word list recall||episodic memory (cogn_ep)|
|cts_wliii||z_WLIII||word list recognition||episodic memory (cogn_ep)|
|cts_ebmt||z_EBMT||East Boston immediate recall||episodic memory (cogn_ep)|
|cts_ebdr||z_EBDR||East Boston delayed recall||episodic memory (cogn_ep)|
|cts_story||z_Story||Logical memory I (immediate)||episodic memory (cogn_ep)|
|cts_delay||z_Delay||Logical memory II (delayed)||episodic memory (cogn_ep)|
|cts_bname||z_BName||Boston naming (15 items)||semantic memory (cogn_se)|
|cts_catflu||z_CatFlu||category fluency||semantic memory (cogn_se)|
|cts_read_nart||z_read_nart||reading test - (10 items)||semantic memory (cogn_se)|
|cts_df||z_DF||digits forward||working memory (cogn_wo)|
|cts_db||z_DB||digits backward||working memory (cogn_wo)|
|cts_doperf||z_DOperf||digit ordering||working memory (cogn_wo)|
|cts_lopair||z_LOpair||line orientation||perceptual orientation (cogn_po)|
|cts_pmat||z_PMat||progressive matrices (16 items)||perceptual orientation (cogn_po)|
|cts_sdmt||z_SDMT||symbol digits modality-oral||perceptual speed (cogn_ps)|
|cts_nccrtd||z_NCcrtd||number comparison||perceptual speed (cogn_ps)|
|cts_stroop_cname||z_cname||stroop color naming||perceptual speed (cogn_ps)|
|cts_stroop_wread||z_wread||stroop word reading||perceptual speed (cogn_ps)|
Item level variables are available upon request.
Note: This variable is calculated if more than half of the z-scores are non-missing. Since the variable is calculated based on the number of valid test scores independent of the domain score calculations, participants may have a valid global score but be missing one or more domain scores.
The number of tests used to compute the global cognitive function score may vary based on the combination of studies used in analysis.