Potential bias in the neuropsychological testing
| Factor | Suggestions to avoid effect of bias |
| Worsened performance | |
| Noisy or overstimulating environment | Perform neuropsychological evaluation in the appropriate environment |
| Fatigue or sleepiness | Avoid neuropsychological assessment in the evening or when tired Provide a break |
| Agitation, distrust, anxiety or fear | Explain the aims of the assessment and how it works Use positive feedback (eg, ‘well done’) Provide a break |
| Depression or apathy | Schedule a follow-up assessment when mood or motivation has improved |
| Non-native speaker | Assess with the help of an interpreter Use non-verbal tests |
| Medication adverse effects (eg, anticholinergics, benzodiazepines, narcotics, neuroleptics, antiepileptics and antihistamines) | Schedule the neuropsychological assessment when off medication or when the drug side effects are lower Be aware of each drug’s adverse effect |
| Visual impairment | Use oral tests |
| Hearing impairment | Speak loudly, and check for understanding |
| Pain or headache | Reschedule for when pain-free |
| Improved performance | |
| Practice | Avoid repeating assessment too frequently Use parallel forms or similar tests |