One hypothesis concerns the selective vulnerability of certain brain areas such as the amygdala, which may be more susceptible to β-amyloid, tau, or α-synuclein deposits.242,243 Anatomical mapping studies have shown the amygdala is affected only later in the course of Lewy body spectrum diseases.244, -246 Nevertheless, subtle changes in brainstem neuronal projections may be present early, leading to limbic circuit dysfunction.6,121,247, -249 This hypothesis is supported by functional imaging studies performed in patients with prodromal PD.250,251. The gene discussed is MAPT; the disease is Parkinson disease.