Observational Study of Cognitive Outcomes for Subjects Who Have Had Prior PET Amyloid Imaging With Florbetapir F 18 (18F-AV-45)

Change in ADAS-Cog for MCI Subjects

The primary analysis was the comparison in the magnitude of change from baseline in Alzheimer's Disease Assessment Scale cognitive subscale (ADAS-Cog) between Aβ+ and Aβ- subjects in the Mild Cognitive Impairment (MCI) population at 36 months adjusting for baseline test score and age at informed consent. ADAS-Cog scores (range 0-70) indicate performance on a series of 11 cognitive tasks where 0 indicates the highest level of cognitive performance and 70 indicates the lowest level of cognitive performance. Change in ADAS-Cog scores were calculated by subtracting the baseline score from the 36 month score (last observation carried forward [LOCF]). A change in ADAS-Cog greater than 0 indicates a deterioration in cognitive performance whereas a change in ADAS-Cog less than 0 indicates improved cognitive performance.

Cognitive Decline in MCI Subjects

The key secondary analyses compared the number of Aβ+ and Aβ- subjects in the MCI population with clinically significant deterioration in ADAS-Cog (≥4) and Clinical Dementia Rating (CDR) global score (≥0.5) and conversion in diagnosis from MCI at baseline to AD or Cognitively Normal (CN) at 36 months. ADAS-Cog scores (range 0-70) indicate performance on a series of 11 cognitive tasks where 0 indicates the highest level of cognitive performance and 70 indicates the lowest level of cognitive performance. CDR scores (range 0-3) quantify the severity of the symptoms of dementia where 0 indicates no cognitive impairment and 3 indicates severe dementia. Changes in ADAS-Cog and CDR scores were calculated by subtracting the baseline score from the 36 month score (LOCF).

Change in ADAS-Cog in CN and AD Subjects

This analysis compared the magnitude of change from baseline in ADAS cognitive subscale (ADAS-Cog) scores between Aβ+ and Aβ- subjects in the CN and AD populations at 36 months adjusting for baseline test score and age at informed consent. ADAS-Cog scores (range 0-70) indicate performance on a series of 11 cognitive tasks where 0 indicates the highest level of cognitive performance and 70 indicates the lowest level of cognitive performance. Change in ADAS-Cog scores were calculated by subtracting the baseline score from the 36 month score (LOCF). A change in ADAS-Cog greater than 0 indicates a deterioration in cognitive performance whereas a change in ADAS-Cog less than 0 indicates improved cognitive performance.

Cognitive Decline in CN and AD Subjects

The key secondary analyses compared the number of Aβ+ and Aβ- subjects in the CN and AD populations with clinically significant deterioration in ADAS-Cog (≥4) and CDR global score (≥0.5). ADAS-Cog scores (range 0-70) indicate performance on a series of cognitive tasks where 0 indicates the highest level of cognitive performance and 70 indicates the lowest level of cognitive performance. CDR scores (range 0-3) quantify the severity of the symptoms of dementia where 0 indicates no cognitive impairment and 3 indicates severe dementia. Changes in ADAS-Cog and CDR scores were calculated by subtracting the baseline score from the 36 month score (LOCF).

Covariate Adjusted Psychometric Score Change

Change from baseline by diagnostic group in covariate-adjusted psychometric assessment scores at month 36 (LOCF). Assessments included Digit Symbol Substitution (DSS), Clinical Dementia Rating Sum of Boxes (CDR-SOB), Mini-Mental State Examination (MMSE), Wechsler Logical Memory Scale (WLMS) delayed and immediate recall, Category Verbal Fluency (CVF) animals and vegetables, Alzheimer's Disease Clinical Studies Consortium Activities of Daily Living (ADCS ADL) and Geriatric Depression Scale (GDS). The ranges for these scales are as follows: DSS (0-93), CDR-SOB (0-18), MMSE (0-30), WLMS delayed and immediate recall (0-25), CVF animals and vegetables (0-total number of relevant items named in 60 seconds), ADCS ADL (0-78) and GDS (0-15). For all scales except CDR-SOB and GDS a higher score indicates greater cognitive function. For CDR-SOB and GDS a higher score indicates increased dementia or depression, respectively.

Correlation of Change in ADAS-Cog and SUVR

Correlation between change from baseline to 36 month ADAS-Cog score and baseline global average SUVR by diagnostic group is provided below. ADAS-Cog scores (range 0-70) indicate performance on a series of 11 cognitive tasks where 0 indicates the highest level of cognitive performance and 70 indicates the lowest level of cognitive performance. Change in ADAS-Cog scores were calculated by subtracting the baseline score from the 36 month score (LOCF). A change in ADAS-Cog greater than 0 indicates a deterioration in cognitive performance whereas a change in ADAS-Cog less than 0 indicates improved cognitive performance. Standard Uptake Value Ratio (SUVR) is the ratio of tracer uptake in the cortex and cerebellum. SUVR values higher than 1 indicate greater amyloid burden in the cortex as compared to the cerebellum whereas scores less than 1 indicate the opposite.