Cognitive deficits and reduced insight in primary progressive aphasia.

Primary progressive aphasia (PPA) is a form of dementia caused by frontotemporal lobar degeneration. Unlike aphasia due to stroke, in which the association between particular aphasia profiles and insight has been well characterized, this relationship has not been investigated in PPA. Reduced insight is seen in other neurological conditions, but tends to involve right hemisphere damage, whereas PPA is predominantly a left hemisphere disorder. The aim of the current study was to examine whether fluent aphasia with less meaningful speech output, associated with diminished insight in stroke, is also characteristic of PPA patients with reduced insight. Fourteen PPA patients were studied. Results indicated that reduced information content in speech and poor performance on a nonlanguage test, the Pyramids and Palm Trees test, predicted reduced insight. This study has implications for the anatomical network involved in insight and clinical implications in terms of selecting interventions appropriate for individual patients with PPA.