TSPO and depressive disorder: A previous study with [11C]PBR28 combining data on altogether 140 healthy control subjects from our center and two other centers indicated that age is associated with TSPO availability in the frontal and temporal cortices, but not in the total gray matter or the parietal or occipital cortices, hippocampus or thalamus.28 The participants of the present study were notably older than the participants of the studies focusing on depression.