Increased frequency of learning disability in patients with primary progressive aphasia and their first-degree relatives

Background: Although risk factors for Alzheimer disease have been well studied, much less is known about risk factors for primary progressive aphasia (PPA). Objective: To demonstrate that learning disabilities (LDs) are more common in patients with PPA and their first-degree family members. Design, Setting, and Patients: Self-report endorsement of an individual and family history of an LD in a sample of 699 subjects from the Northwestern Alzheimer's Disease Center registry. We compared 3 dementia groups (PPA, typical amnestic Alzheimer disease, and the behavioral variant of frontotemporal dementia) and 1 elderly control group. A retrospective medical record review in the PPA probands was used to obtain additional information. Main Outcome Measure: Prevalence of LDs among probands and their first-degree relatives. Results: The patients with PPA and their first-degree family members had a significantly higher frequency of LD compared with the other dementia groups and the controls. Some of the families of patients with PPA displayed unusual concentrations of LD, especially dyslexia. Conclusion: These results suggest that LD may constitute a risk factor for PPA, providing additional clues concerning the determinants for the selective vulnerability of the language network in this syndrome.