The analysis was conducted using data contained in the Integrated Data Infrastructure (ITI), an de-identified or anonymous database of New Zealand’s contacts with government services. The leading author is Leah Richmond-Rockert, a professor at the University of Michigan, and this study was published in
Results were held for both men and women, for early and late onset dementia, Alzheimer’s and non-Alzheimer’s dementia, and all types of mental illness, even after calculating pre-existing physical illness and socio-economic deficits. University of Auckland Social Scientist Associate Professor Barry Milne, a co-author of this study, says that mental health predicts dementia much more strongly than physical health and was true for all types of dementia. “This suggests that if we can focus our resources on mental disorders when they peak in adolescence and young adulthood, we may also prevent or delay later dementia.”
Dementia describes a group of brain symptoms that affect memory, thinking and social skills, interfering with daily life and affecting about 70,000 New Zealanders, a number that is projected to double by 2050. Although the cause of the link between early mental health problems and post-dementia has not been definitively established, alcohol, which is often associated with mental disorders, can lead to dementia, or medications for mental disorders, such as antipsychotics, may increase the risk.
Dr. Milne states that it might also be that life-long brain vulnerability manifests itself as mental health problems earlier in life and dementia later in life, with shared genetics causing both. But while the risk for those who experience mental health problems is significantly higher, most people with mental health problems do not develop dementia, he says. “Mental health problems are not ‘life sentences’ that always result in dementia.”
Previous studies to examine the link between mental disorders and dementia tend to assess mental health from mid-life only beyond the peak prevalence in adolescents, and a wide variety of mental conditions are not frequently explored. The mental health conditions included in this study affected four percent of those surveyed, including self-harm, substance use disorders, psychiatric disorders, and mood and neurotic disorders.