The most studied topics related to Hb included lateral habenula (577), ventral tegmental area (256), depression (182), reward (178), dopamine (144), activation (139), substantia nigra (118), prefrontal cortex (116), basal ganglia (111), and nucleus accumbens (108), while the most recent emergent topics were circuits (average publication year of 2019), fear (2018), dependence (2018), aversion (2018), major depressive disorder (2018), and anxiety (2017). This evidence concerns the gene GSTM1 and depressive disorder.