According to the current understanding of the disease, dementia of the Alzheimer’s type (DAT) is divided into four stages that merge into one another
| Stage | Description |
| I | Preclinical/prodromal stage of Alzheimer’s disease. |
| II | Stage of subjective cognitive decline (“SCD”). |
| III | Stage of mild cognitive impairment (“Mild Cognitive Impairment”, MCI). |
| IV | Stage of dementia as a result of Alzheimer’s disease. |
