Neuropsychiatric Symptoms in Primary Progressive Aphasia: Phenomenology, Circuits, and Clinical Management.

PURPOSE OF REVIEW: This review synthesizes evidence on the phenomenology, neurobiology, assessment, and treatment of neuropsychiatric symptoms in primary progressive aphasia (PPA), with emphasis on variant-specific patterns and consequences.

RECENT FINDINGS: Neuropsychiatric symptoms are pervasive across PPA and extend beyond language impairment. Contemporary studies identify affective, active behavioural, passive behavioural, and psychotic dimensions, with the greatest behavioural burden observed in semantic variant PPA and apathy prominent across non-fluent/agrammatic and logopenic phenotypes. Converging structural, functional, and molecular evidence implicates distributed language, salience, limbic, and frontostriatal networks, alongside serotonergic and dopaminergic dysfunction. Emerging manifestations, including Problematic Internet Use, broaden the recognised behavioural spectrum. Neuropsychiatric symptoms are integral determinants of disability, caregiver burden, and clinical complexity in PPA. Routine, caregiver-informed assessment and multidisciplinary, non-pharmacological-first management are warranted. Future studies should validate PPA-specific measures, clarify longitudinal trajectories, test targeted interventions, and determine whether neuropsychiatric features should be incorporated into revised PPA diagnostic criteria.