Young-onset dementia: A practical approach to diagnosis

Background: Young-onset dementia is best defined as dementia presenting at age less than 65 years. And, while cognitive impairment in the elderly is dominated by dementia of the Alzheimer type, young-onset dementia has a vast differential diagnosis. Review Summary: This article reviews an extensive differential diagnosis for young-onset dementia by utilizing different clues in the historical records and laboratory findings to aid with diagnosis. Laboratory testing should be completed in at least 2 stages. In the first stage, referred to as the first "wave," we suggest more routine testing, particularly for treatable causes of dementia. The second "wave," which we also outline, emphasizes more esoteric testing that may require referral to a tertiary care medical facility. The manuscript is divided into 2 parts, with part 1 focusing on clues from the historical data, while part 2 focuses on laboratory abnormalities. Conclusion: Unlike dementia presenting in the elderly, the differential diagnosis in young-onset dementia is vast. A thorough historical review of the symptoms, with special emphasis on the pattern of cognitive impairment, temporal profile of the disease, detailed family history, and extensive but coordinated laboratory and ancillary testing, may yield subtle clues to the diagnosis.