Complex sentence: Estrogen has direct effects on the hippocampus, which in turn relates to mood, including increasing dendritic spine density and increasing the volume and neurogenesis of the hipposcampus; these are key to greater cognition as key neuronal circuits are maintained.
Split into simpler sentences: Estrogen has direct effects on the hippocampus, which in turn relates to mood, including increasing dendritic spine density and increasing the volume and neurogenesis of the hipposcampus. All of which are key to greater cognition as key neuronal circuits are maintained.