People with substance-induced psychosis appear to be at a greater risk of dying earlier than those who do not experience psychosis, according to a study in Addiction. The analysis revealed that the risk of death was elevated in people with substance-induced psychosis regardless of whether they later developed schizophrenia.
“Although not necessarily a causal finding, this provides a strong rationale for monitoring people with [a] previous diagnosis of substance-induced psychosis and developing and implementing interventions to reduce this excess mortality,” wrote Carsten Hjorthøj, Ph.D., M.Sc., of the University of Copenhagen and colleagues.
Hjorthøj and colleagues examined data from the nationwide Danish registers, specifically focusing on individuals who were born in Denmark, lived in Denmark at age 15, and were 15 or older between the study period of January 1, 1994, and August 10, 2017. The population was followed until death, emigration, or August 10, 2017, whichever came first.
Of the more than 5.6 million people included in the study, 9,303 were diagnosed with substance-induced psychosis only, 2,197 were diagnosed with schizophrenia following substance-induced psychosis, and 39,738 were diagnosed with schizophrenia without preceding substance-induced psychosis.
A total of 1,240,860 people died during the follow-up period. After adjusting for such variables as age, sex, and parental history of schizophrenia and substance use disorder, the researchers found that people with substance-induced psychosis were more than six times as likely to die during the follow-up period as those who had never been diagnosed with substance-induced psychosis or schizophrenia. The risk of death in people with substance-induced psychosis who later developed schizophrenia was even greater; they were nearly 10 times as likely to die as those who had never been diagnosed with either substance-induced psychosis or schizophrenia. For comparison, people who had been diagnosed with schizophrenia without preceding substance-induced psychosis were three times as likely to die during the follow-up period. Those with substance-induced psychosis (including those who did and did not develop schizophrenia) appeared to be at a particularly high risk of suicide and accidental deaths compared with those without substance-induced psychosis.
“[O]ur results make it abundantly clear that people with substance-induced psychosis have a highly increased risk of both all-cause and cause-specific mortality, even if they do not progress to being diagnosed with schizophrenia,” the authors concluded.
For related information, see the American Journal of Psychiatry article “Prediction of Onset of Substance-Induced Psychotic Disorder and Its Progression to Schizophrenia in a Swedish National Sample.”