SV2A and Lewy body dementia: We propose that DLB is associated instead with severe synaptic loss, and we test this hypothesis in vivo using positron emission tomography (PET) imaging of <sup>11</sup>C-UCB-J, a ligand for presynaptic vesicle protein 2A (SV2A), a vesicle membrane protein ubiquitously expressed in synapses.<h4>Methods</h4>We performed <sup>11</sup>C-UCB-J PET in two DLB patients (an amyloid-negative male and an amyloid-positive female in their 70s) and 10 similarly aged healthy controls.