Irregular moods and personality and behavioral changes. A tumor in the brain can result in a considerable alteration of the personality, with the individual exhibiting character traits that they perhaps did not possess before. A person might become subject to anxiety, or be easily depressed. This is because the centers that control personality lie in the frontal lobe, and pressure on these areas can actually alter the personality. Other behaviors can include anger, sexual promiscuity, or agitation. A previously inhibited person may become very uninhibited, and a previously cautious person may lose their caution.