Schizophrenia occurs in about 1 percent of the general U.S. population. That means that more than 3 million Americans suffer from the illness.

The disorder manifests itself in a broad range of unusual behaviors, which cause profound disruption in the lives of the patients suffering from the condition and in the lives of the people around them. Schizophrenia strikes without regard to gender, race, social class or culture.

One of the most important kinds of impairment caused by schizophrenia involves the person’s thought processes. The individual can lose much of the ability to rationally evaluate his surroundings and interactions with others.

There can be hallucinations and delusions, which reflect distortions in the perception and interpretation of reality. The resulting behaviors may seem bizarre to the casual observer, even though they may be consistent with the schizophrenic’s abnormal perceptions and beliefs.

Nearly one-third of those diagnosed with schizophrenia will attempt suicide. About 10 percent of those with the diagnosis will commit suicide within 20 years of the beginning of the disorder.

Patients with schizophrenia are not likely to share their suicidal intentions with others, making life-saving interventions more difficult. The risk of depression needs special mention due to the high rate of suicide in these patients.

The most significant risk of suicide in schizophrenia is among males under 30 who have some symptoms of depression and a relatively recent hospital discharge. Other risks include imagined voices directing the patient toward self-harm (auditory command hallucinations) and intense false beliefs (delusions).

The relationship of schizophrenia to substance abuse is significant. Due to impairments in insight and judgment, people with schizophrenia may be less able to judge and control the temptations and resulting difficulties associated with drug or alcohol abuse.

In addition, it is not uncommon for people suffering from this disorder to try to “self-medicate” their otherwise debilitating symptoms with mind-altering drugs. The abuse of such substances, most commonly nicotine, alcohol, cocaine and marijuana, impedes treatment and recovery.

The chronic abuse of cigarettes among schizophrenic patients is well-documented and probably related to the mind-altering effects of nicotine. Some researchers believe that nicotine affects brain chemical systems that are disrupted in schizophrenia; others speculate that nicotine counters some of the unwanted reactions to medications used to treat the disease.

It is not uncommon for people diagnosed with schizophrenia to die prematurely from other medical conditions, such as coronary artery disease and lung disease. It is unclear whether schizophrenic patients are genetically predisposed to these physical illnesses or whether such illnesses result from unhealthy lifestyles associated with schizophrenia.