Early life mental disorders linked to earlier onset dementia

By Melanie Hinze
People with mental disorders in early life are at increased risk of developing dementia, and developing dementia at an earlier age, according to new research published in JAMA Psychiatry.

Researchers conducted a population­-based administra­tive register study of mental disorders and Alzheimer disease and related dementias. A total of 1,711,386 individuals, aged 21 to 60 years at baseline, were included in the study. Participants were born in New Zealand between 1928 and 1967, and resided in the country at any point from July 1988 to June 2018.

Participants with a mental disorder had a more than four times increased risk of develop­ing subsequent dementia. Those with a mental disorder also developed dementia a mean of 5.6 years earlier than those without a mental disorder.

Associations were present across different types of mental disorders, including psychotic disorder, substance use disorder, mood disorder, anxiety disorder and self­-harm.

Associate Professor Nadeeka Dissanayaka, Head of the Dementia & Neuro Mental Health Research Unit at the UQ Centre for Clinical Research, The University of Queensland, Brisbane, said this was a timely study, relevant to the present pandemic climate.

She said that although dementia was usually known as an age-related disease pre­dominantly observed in older persons, this study showed that those individuals with a mental disorder could develop dementia at younger ages.

‘So in the GP practice it’s important to discuss any signs of mental dysfunction and to make use of screening tools,’ she said, noting that the most appropriate tools changed as people aged. She added that although we should be treating young people in the early stages, it was important not to forget older people.

‘There’s strong evidence to suggest that there has been an increase in mental health issues because of the pandemic, which is relevant to this study,’ Associate Professor Dissanayaka also noted.

‘COVID­19 can trigger a significant spike in dementia due to neurological impact, and a rise in associated mental disorders will only exacerbate this dementia risk. Countries where the pandemic has been worse are already showing evidence of dementia symptoms emerging earlier’ she said. ‘It’s possible Australia will see similar effects in the next couple of years or so.’
JAMA Psychiatr 2021; doi: 10.1001/jamapsychiatry.2021.4377.