Cognitive Errors in Neurodegenerative Diseases and Traumatic Brain Injury

Definition and Clinical Manifestations

• Patients with dementia or neurodegenerative disease exhibit cognitive errors, such as repetitive questions or conversations, misplacing personal belongings, forgetting events or appointments, getting lost on familiar routes, and missed appointments, indicating failures in real-world planned thought and action 1
• Cognitive errors in this population also include difficulty remembering or following instructions, reflecting working memory and executive dysfunction, and medication management errors, demonstrating complex task sequencing failures 2

Relationship to Objective Cognitive Performance

• The American Academy of Neurology recommends that collateral informant history is essential, as patients often cannot reliably report their own cognitive errors due to diminished insight 2, 3

Clinical Assessment Approach

• The National Institute on Aging suggests obtaining a collateral history by interviewing a reliable informant separately using validated tools like AD8 or IQCODE 4
• The American College of Physicians recommends using validated objective testing, such as the Montreal Cognitive Assessment (MoCA), for detecting mild impairment 2, 4
• The Alzheimer's Association suggests that formal neuropsychological testing is indicated when bedside testing cannot provide confident diagnosis 1

Critical Pitfalls to Avoid

• The American Geriatrics Society advises against attributing cognitive errors to "normal aging" without objective assessment, as changes common with advancing age are not always normal and warrant diagnostic evaluation 6
• The American Academy of Neurology recommends not relying on patient self-report alone, as diminished insight is common, and divergent perspectives between patient and informant provide valuable diagnostic clues 6, 4