Table 1 Inclusion and exclusion criteria

Inclusion criteria

1. Clinical diagnosis of PCA based on clinical presentation and formal neuropsychological assessment suggestive of significant visuo-perceptual or visuo-spatial disturbance, visual disorientation, apraxia, dysgraphia or dyscalculia in the context of relatively preserved memory

2. Performance below the 5th percentile on two of the following four tests of parietal lobe function:

 • Jackson and Warrington calculation test [21]

 • number location visual spatial test [9]

 • object decision visual perceptual test [9]

 • Baxter and Warrington spelling test [22]

3. Verbal memory test score above the 5th percentile on a neuropsychological assessment such as the verbal recognition memory test [23]

4. Absence of alternative cause of cognitive impairment based on clinical history and examination, and available investigations including blood tests, electroencephalograph, MRI of brain and formal neuropsychological assessment

Exclusion criteria

1. Significant neurological or psychiatric disease that may affect cognition other than Alzheimer’s disease

2. Significant systemic disease that may deteriorate or affect the patient’s safety or the ability to cooperate with the study protocol

3. Medications with the potential to affect cognition unless maintained on a stable dose for at least 3 months prior to week 0 visit

4. Patients with lactose intolerance

5. Known hypersensitivity to donepezil hydrochloride, piperidine derivatives, or to any excipients used in the formulations