What are the key diagnostic criteria for Alzheimer's disease in a primary care setting?

In a primary care setting, the key steps for assessing suspected Alzheimer's disease focus on initial evaluation, ruling out reversible causes of cognitive decline, and determining the need for specialist referral, rather than providing a definitive diagnosis of Alzheimer's disease itself ¹,².

The initial assessment in primary care involves:

• Taking a comprehensive history: This should be gathered from the person with suspected dementia and, if possible, from someone who knows them well (such as a family member). The history should cover cognitive, behavioural, and psychological symptoms, as well as their impact on daily life ¹.
• Physical examination and investigations: If dementia is still suspected after the initial history, a physical examination should be conducted, along with appropriate blood and urine tests to exclude reversible causes of cognitive decline ¹.
• Excluding reversible causes: It is crucial to investigate and rule out conditions that can mimic dementia, including delirium, depression, sensory impairment (such as sight or hearing loss), or cognitive impairment caused by medicines associated with increased anticholinergic burden ¹,².
• Cognitive testing: A validated brief structured cognitive instrument should be used, such as the 10-point cognitive screener (10-CS), the 6-item cognitive impairment test (6CIT), the 6-item screener, the Memory Impairment Screen (MIS), or the Mini-Cog, or Test Your Memory (TYM) ¹. However, dementia should not be ruled out solely based on a normal score on a cognitive instrument ¹.
• Using informant questionnaires: When taking a history from someone who knows the person well, consider supplementing it with a structured instrument like the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) or the Functional Activities Questionnaire (FAQ) ¹.

If, after these investigations, dementia is still suspected and reversible causes have been ruled out, the person should be referred to a specialist dementia diagnostic service, such as a memory clinic or community old age psychiatry service, for a definitive diagnosis ¹,². Specialist services will then use validated criteria, such as the National Institute on Aging (NIA) criteria for Alzheimer's disease, and may conduct further tests like verbal episodic memory tests, neuropsychological testing, or structural imaging ¹.