Probable Alzheimer's disease is diagnosed if either of the following is present ; oth erwise, possible Alzheimer's disease should be diagnosed .
1. Evidence of a causative Alzheimer's disease genetic m utation from family history or genetic testing.
2. . All three of the following are present:
a. Clear evidence of decline in memory and learning and at least one other cogni tive domain (based on detailed history or serial neuropsychological testing).
b. Steadily progressive, gradual decline in cognition , without extended plateaus.
c. No evidence of mixed etiology (i.e., absence of other neurodegenerative or cerebrovascular disease, or another neurological, mental , or systemic disease or condition likely contributing1to cognitive decline).