Hallucinations in the General Population Tied to Psychiatric Disorders

Hallucinations in the general population are significantly linked to mental health disorders, suicidal ideation, and suicide attempts across the lifespan, new research shows.

An analysis of a large survey of more than 33,000 participants showed that although the prevalence of hallucinations decreased markedly with age, individuals who reported hallucinations were at least twice as likely to have at least one mental disorder than their counterparts without hallucinations.

They were also more than twice as likely to report suicidal ideation and suicide attempt across the lifespan, although, again, the rate of both outcomes decreased with age.

A possible reason for the decreasing rate could be that "maladaptive coping skills and high levels of emotional dysregulation increase the risk of hallucinations, [but] these are skills that are known to improve as adults age," study investigator Kathryn Yates, PhD student, Department of Psychiatry, Royal College of Surgeons, Dublin, Ireland, noted.

Still, Yates believes the findings highlight the "important life course and developmental features of hallucinations from early adulthood to old age."

"If an individual comes into the clinic and they're 19 and they report past-year hallucinations but there's also someone in the waiting room aged 74 who reports past-year hallucinations, which individual are you going to be more concerned about in terms of psychopathology?" she asked.

The current study highlights the intricacies of that dilemma "quite well," said Yates, who presented the findings at the virtual Congress of the Schizophrenia International Research Society (SIRS) 2021.

Transdiagnostic Condition

Previous research shows "hallucinations and psychotic experiences in general are more common in younger populations, with a prevalence of 17% in children, 8% in adolescents, and between 5% and 8% in adults," Yates told meeting attendees.

In addition, hallucinations are associated with a wide range of adverse outcomes, including anxiety, depression, schizophrenia, and brief psychotic disorder. "So they are transdiagnostic," and also associated with suicidality, she said.

While hallucinations become less prevalent as children enter adolescence and predict psychopathology, to date there's been no research investigating the relationship between hallucinations and mental disorders across the adult lifespan, Yates said.

For the current analysis, investigators gathered data from the Adult Psychiatric Morbidity Survey, a cross-sectional study of a sample of the UK general population conducted every 7 years since 1993.

They combined all four datasets from 1993, 2000, 2007, and 2014, for a total study population of 33,637 individuals aged 16 to 95 years. Of these, 56% were women.

Across the entire sample, 4% of participants (58% women) reported experiencing hallucinations in the previous year — a rate similar to that reported in previous studies.

Yates noted the prevalence of hallucinations "decreased with age," from approximately 7% in those aged 16 to 19 years to less than 3% in those aged 70 years or older.

In addition, 17% of the participants (66% women) had at least one mental disorder, with the prevalence again decreasing with age — particularly after 50 to 59 years.

However, Yates noted that within each age group, individuals with hallucinations had a far higher prevalence of mental disorders than those without.

Suicide Risk

Between ages 16 to 19 years and 50 to 59 years, approximately 40% of the participants with hallucinations had at least one mental disorder compared with approximately 10% to 20% of those without hallucinations.

Among those aged 70 years and older, the prevalence of at least one mental disorder was more than 20% in those with hallucinations versus less than 10% in those without.

Yates said this relationship between hallucinations and mental health disorders was "clearer to see" when looking at suicide outcomes.

In the total group, 17% reported lifetime suicidal ideation and 5% reported at least one lifetime suicide attempt; and the prevalence was far higher in individuals with hallucinations than in those without.

Prevalence of suicidal ideation in the participants aged 16 to 19 years was almost 50% in those with hallucinations versus less than 20% in those without. For suicide attempts, the figures were more than 20% versus just over 5%, respectively.

In individuals aged 70 years or older, prevalence of suicidal ideation was approximately 20% in those with hallucinations and less than 10% in those without. Suicide attempts were reported by just over 5% of those with hallucinations and by less than 2% of those without.

Yates said there are a number of potential mechanisms that may explain the relationship between hallucinations and mental health outcomes and suicide. These include a decline in coping and problem-solving skills.

For instance, she noted some research shows "individuals with psychotic experiences are less able to cope with life stresses," which has also been shown with suicidal ideation.

Consequently, the "two could share mechanisms" that increase the risk of both psychotic experiences and suicidal behavior, said Yates. It could also be a direct association via psychotic experiences, such as with command hallucinations, she added.

Superficial Analysis?

Commenting on the findings for Medscape Medical News, Jean-Pierre Lindenmayer, MD, director of the Psychopharmacology Research Unit, Manhattan Psychiatric Center, Nathan S. Kline Institute for Psychiatric Research, Orangeburg, New York, called the study "superficial" and "rather simplistic."

Lindenmayer noted a number of unanswered questions in the research, such as what definition of "hallucinations" was used, whether the survey asked about all types of hallucinations, how participants were asked about their hallucinations, and how the psychotic diagnoses were established.

Another phenomenon not touched upon "are people who do not carry any mental illness diagnosis, but hear voices and cultivate them," he said.

An example of this cited by Lindenmayer is the worldwide, collaborative Hearing Voices Network, which states that it "does not start from the assumption that [these individuals] have a chronic illness."

Yates and Lindenmayer have reported no relevant financial relationships.

SIRS 2021. Abstract 3007218. Presented April 20, 2021.

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