Diagnosis of mental disorders linked to higher risk for dementia

Diagnosis of mental disorders was associated with an increased risk for the onset of dementia later in life, according to results of a population-based administrative register study published in JAMA Psychiatry.

“Old age brings risk for many physical diseases, but neurodegenerative conditions, including Alzheimer’s disease and related dementias, have a disproportionate impact on disability and loss of independence in older adults,” Leah S. Richmond-Rakerd, PhD, of the department of psychology at the University of Michigan, and colleagues wrote.

“Recognition of the outsized influence of dementia on later-life functioning has fueled research into modifiable risk factors and prevention targets.”

Richmond-Rakerd and colleagues conducted a study to find out whether mental disorders are a reliable predictor and antecedent for dementia across a 3-decade window. The study examined more than 1.7 million individuals born in New Zealand between 1928 and 1967 who resided in the country for any time from July 1988 to June 2018. Data were collected from the New Zealand Integrated Data Infrastructure, a collection of whole-of-population administrative data sources linked at the individual level.

Diagnoses of mental disorders were collected from public hospital records, while Alzheimer’s disease and dementia diagnoses were found within public -hospital, mortality and pharmaceutical records. Data were analyzed from October 2020 to November 2021.

Results showed that relative to individuals without a mental disorder, those with a mental disorder were at increased risk for developing dementia (RR = 4.24; 95% CI, 4.07-4.42; HR = 6.49; 95% CI, 6.25-6.73). Among dementia cases, those diagnosed with a prior mental disorder developed dementia within a mean duration of 5.6 years (95% CI, 5.31-5.9) earlier than those without.

“Associations were observed across different mental disorders, suggesting that preventing any disorder in early life might benefit later-life cognitive health,” Richmond-Rakerd and colleagues wrote. “However, different mechanisms may connect different disorders with dementia. Characterizing shared and unique pathways of risk for dementia across different psychiatric disorders should be a research priority.”