Dementia Rate ‘Markedly Elevated’ in Older Adults With Schizophrenia

More than a quarter of US adults with schizophrenia received a diagnosis of dementia before 66 years of age, according to a retrospective cohort study of Medicare beneficiaries published online ahead of print in JAMA Psychiatry. 

“Notably, the prevalence of diagnosed dementia among people with schizophrenia at 66 years of age was similar to the prevalence of diagnosed dementia at 88 years of age for the group without serious mental illness,” researchers wrote.

The study included more than 8 million patients in a national Medicare database from 2007 to 2017. Some 74,170 of participants had a diagnosis of schizophrenia.

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According to the study, dementia incidence was increased in participants with schizophrenia across the older adult life span but was greatest at younger ages. At age 66, the prevalence of dementia was a “markedly elevated” 27.9% in patients with schizophrenia, researchers reported, compared with 1.3% among patients without schizophrenia, bipolar disorder, or recurrent major depressive disorder. At age 80, 70.2% of patients with schizophrenia had a dementia diagnosis compared with 11.3% of patients without serious mental illness.

The study found increased rates of dementia in people with schizophrenia for men, women, and all racial/ethnic groups.

“It is not known why some adults but not others with schizophrenia undergo progressive cognitive decline decades before the usual onset of dementia in the general population,” researchers wrote. “Identification of modifiable risk factors, possibly including anticholinergic medications, inadequately treated psychosis, and comorbid medical conditions such as hypertension and diabetes, may help focus prevention efforts.” 

—Jolynn Tumolo

Reference

Stroup TS, Olfson M, Huang C, Wall MM, Goldberg T, Devanand DP, Gerhard T. Age-specific prevalence and incidence of dementia diagnoses among older us adults with schizophrenia. JAMA Psychiatry. 2021 March 10;[Epub ahead of print].