Frontotemporal Dementia

This article discusses frontotemporal dementia (FTD) syndromes using a simplified framework of three core syndromes, including details on their pathology and unique genetic variations.

FTD includes at least seven major clinical syndromes. The three core syndromes are behavioral variant FTD and two forms of progressive aphasia, commonly referred to as the nonfluent variant and semantic variant of primary progressive aphasia. Clinical features reflect the involvement of major functional brain networks. Derangements of three proteins account for nearly all underlying pathology for FTD syndromes: transactive response DNA-binding protein 43 (TDP-43) (approximately 50% of cases), MAPT (45% of cases), and FUS (5% of cases). The clinical presentation and imaging provide clues to the underlying pathology. FTD is more heritable than Alzheimer disease, with variations in C9orf72, MAPT, or GRN (which encodes progranulin) occurring in more than 10% of FTD cases.

The framework described here will provide clinicians with a foundation for understanding the complex and heterogeneous set of FTD syndromes. There are currently no disease-modifying or US Food and Drug Administration (FDA)-approved treatments for FTD, but clinical trials are underway, including some targeting presymptomatic genetic variation carriers. Available FTD treatments address deficits in behavior or language nonpharmacologically or through the off-label use of medications approved for other indications. Improvements in biomarkers will accelerate the discovery of new pharmacologic treatments.