Table 1

Comparison of possible trial designs at different stages of Alzheimer's disease neurobiology

Mild AD Trial

Early AD Trial

Very early AD Trial


Cognitive status

Mild dementia

Mild cognitive impairment

Cognitively normal

CDR global score

0.5 to 1

0.5

0

MMSE range

16 to 26

25 to 30

28 to 30

Biomarker for subject selection

None

Amyloid imaging and/or CSF Aβ42

Amyloid imaging and/or CSF Aβ42

Biomarker for subject stratification

None or APOE genotype

APOE genotype

APOE genotype

Primary cognitive outcome measure

ADAS-cog11

ADAS-cog12 (includes delayed recall)

Sensitive memory and/or executive function measure

Primary global/functional outcome measure

CDR-SB

CDR-SB

None

Analysis covariates

Baseline cognition and regional brain volume

Baseline cognition and regional brain volume

Regional brain volume

Biomarker outcome

Regional brain atrophy

Regional brain atrophy

Regional brain atrophy and/or amyloid measure (as surrogate endpoint)

Duration of treatment

18 months

24 months

24 to 36 months

Primary analysis

Change score or slope of co-primaries: ADAS-cog11, CDR-SB

Change score or slope of co-primaries: ADAS-cog12, CDR-SB

Regional brain atrophy rate and cognitive decline


AD = Alzheimer's disease; ADAS-cog = Alzheimer's Disease Assessment Scale-cognitive subscale; APOE, apolipoprotein E; CDR-SB = Clinical Dementia Rating 'sum of boxes'; CSF = cerebrospinal fluid; MMSE, Mini-Mental State Examination.

Aisen Alzheimers Res Ther 2009 1:2   doi:10.1186/alzrt2