Figure 1. Clock drawings from four patients with varying severity of Alzheimer disease, who were asked as part of a neuropsychological test: ‘Please draw a clock. Put the hours on it and set the time at 2:45’.

Figure 2. Light micrograph of Alzheimer disease neuropathology. Section from the cortex of a patient with Alzheimer disease showing tangles and plaques. The intraneuronal tangle (arrow) is stained dark brown with an antibody that specifically targets paired helical filaments. These filaments are also seen as the dense brown material (dystrophic processes) embedded in the extracellular plaque (arrowhead). The lighter reddish staining of the plaque is from another antibody directed specifically against -amyloid.

Figure 3. Schematic diagram of -amyloid precursor protein (APP). The secretase cleavage sites are shown. Cleavages by - and -secretases release A peptides. A_42–43 are the major constituents in amyloid plaques.