There are many connections between delusions and hallucinations. In certain diseases, these two issues coexist, but it typically is important to make a distinction between delusions and hallucinations when determining the source of the problem. Delusions arise when existing signals are misinterpreted, and they can be caused by various mental conditions or drugs. Hallucinations also have many causes, but they are entirely unrelated to any stimuli. Dealing with hallucinations and delusions often involves similar treatments, but the specific strategies used for the two are sometimes slightly different.
Several disorders can cause both delusions and hallucinations, including schizophrenia and Alzheimer’s disease. In most cases, true hallucinations are caused by psychotic disorders, and delusions are caused by a wider variety of problems. It is sometimes difficult to tell whether a symptom is a delusion or a hallucination because the stimulus might not be obvious to either the patient or those around him or her.
Getting to the root of the connection between delusions and hallucinations is more difficult. These problems often respond to similar medication, although the therapy used to treat one or the other might be different. People often react in similar ways to delusions and hallucinations, and reactions might include fear, frustration or even violence. Both problems can be extremely dangerous to a person's health, not simply because they represent malfunctions in the brain, but also because they can cause the individual to act upon false information.
The content of delusions is often quite different from hallucinations. Delusions might lead a person to believe that he or she is being persecuted or that there are secret messages in mass media that are directed specifically to the delusional person. Hallucinations might not be threatening, although it is common for these to take on frightening forms. Generally, auditory hallucinations are more common than other types, and they might include voices. This makes it easier to identify hallucinations, because the voices are not perceived as the person's own thoughts.
Treating delusions and hallucinations both rely on diagnosing the underlying disorder that is causing the problems and using treatment that is appropriate to that disorder. This often involves medications, but when delusions are caused by drug use, the problem might be resolved by not taking drugs. Therapy for these two problems can be divergent because, with delusions, one must learn to understand stimuli differently, and with hallucinations, one must determine whether something is real. Both can be difficult to solve when the person does not recognize the stimuli as false.