What are the key diagnostic criteria for different types of dementia in primary care settings?

In primary care settings, the key steps for diagnosing suspected dementia focus on initial assessment, ruling out reversible causes, and determining the need for specialist referral, rather than definitively diagnosing specific dementia subtypes ¹,².

• Initial Assessment: The process begins with taking a history from the person with suspected dementia and, if possible, from someone who knows them well (e.g., a family member) ². This history should cover cognitive, behavioural, and psychological symptoms, and their impact on daily life ².
• Physical Examination and Tests: 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 ². Reversible causes include delirium, depression, sensory impairment (like sight or hearing loss), or cognitive impairment from medicines with increased anticholinergic burden ¹,².
• Cognitive Testing: Validated brief structured cognitive instruments should be used, such as the 10-point cognitive screener (10-CS), 6-item cognitive impairment test (6CIT), Mini-Cog, or Test Your Memory (TYM) ². However, dementia should not be ruled out solely based on a normal score on a cognitive instrument ². Structured instruments like the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) or the Functional Activities Questionnaire (FAQ) can supplement the history taken from an informant ².
• Referral to Specialist Services: If reversible causes have been investigated and dementia is still suspected, the person should be referred to a specialist dementia diagnostic service, such as a memory clinic or community old age psychiatry service ¹,². Rapidly progressive dementia warrants referral to a neurological service ¹,².
• Specialist Diagnosis: Definitive diagnosis of a dementia subtype, if possible, occurs in specialist services after initial assessment confirms cognitive decline and reversible causes are ruled out ². Specialists use validated criteria for specific subtypes, such as International consensus criteria for dementia with Lewy bodies, NINDS-AIREN criteria for vascular dementia, and NIA criteria for Alzheimer's disease ². Structural imaging (MRI or CT scan) is also part of specialist investigations to rule out reversible causes and assist with subtype diagnosis ¹,².