Delusions and hallucinations are similar yet different. Hallucinations are visual or auditory-based delusions, where one may see things that are not there, or see distorted images. Delusions, however, do not have to be hallucinations, but can be beliefs held that are not consistent with reality.

Common delusions include delusions of grandeur and of persecution. Both types are common with schizophrenia. Delusions of grandeur may also be present in manic episodes of bipolar disorder.

Delusions of grandeur may make a person think he or she is invincible or godlike. They may alternately think their very acts can control everything in their surroundings. These types of delusions can be quite dangerous to the person experiencing them. One might walk into traffic or jump off a building because one is convinced he or she cannot be harmed.

Delusions of persecution tend to make a person think that “everyone” is conspiring against him or her. The person may believe that his or her private conversations are being taped or that a secret government conspiracy exists to steal the thoughts of the world. Usually those with delusions of persecution live very guarded existences, and may perform strange acts to prevent what they consider persecution. If confronted, those with delusions of persecution may become suddenly violent, though this is relatively uncommon.

Both of these types of delusional thinking can be fueled by visual and auditory hallucinations. The person may feel someone else is talking to him or her. The person may also see people or animals that are not there. Delusions of grandeur may result from a hallucination that an angel or saint has visited the person and given them special instructions. Conversely, those with persecutory delusions may see people not present who are coming to destroy them, and thus experience extreme fear.

Hallucinations may also be the result of taking drugs or medications with hallucinogenic properties. Native Americans made use of peyote to evoke visions during vision quests. Many in the drug culture of the late 1960s welcomed the hallucinations brought on by drugs like LSD.

Hallucinations from hallucinogenic drugs can be visual or auditory, but usually do not involve visitations. Instead visual and auditory distortions in one’s surroundings are most common. The drug culture welcomed these distortions and felt that they opened their consciousness to a greater understanding of the world.

Those who purposefully used hallucinogens had a distinct advantage over those with mental illness. They tended to be able to distinguish between delusion and reality when drugs cleared their system. The schizophrenic usually cannot make this distinction without treatment. Even with treatment, some delusions may exist that the schizophrenic must try to block out. Those in manic states of bipolar may be slightly more aware that delusions are not real, and will be especially aware of this in depressed cycles. Again, medical treatment and therapy can help put a stop to delusional thinking or perception.