The biggest risk factor for developing dementia is age. In fact, the odds of getting it happen twice as often after the age of 65. There are many factors that can influence the odds of a person getting dementia. So-called modifiable factors, such as smoking and social isolation, can also play a role in genetic vulnerability. There have been some cases of dementia linked to mental disorders, such as schizophrenia and depression. The causality is a little murky because depression can be a sign that cognitive decline is occurring. A data analysis was conducted earlier in the year. From New ZealandThis study provided the strongest evidence to date linking multiple types of mental illness and dementia. This study raises important questions about why there is an increased risk of developing dementia and what can be done to decrease it.
The study examined the health records for 1.7 million New Zealanders who were born between 1928-1967. It covered a 30-year period that ended in mid-2018. It found that those with a diagnosed mental disorder—such as anxiety disorders, depression or bipolar disorder—had four times the rate of ultimately developing dementia compared with people without such a diagnosis. It was six times higher for those suffering from psychosis, such as schizophrenia. People who had a psychiatric disorder, such as schizophrenia, were more likely to develop dementia 5.6 years before the average.
Although the study didn’t examine any biological, social, or other causes for the higher risk, research on dementia suggests several possibilities. “There might be shared genetic risk factors,” suggests psychologist Leah Richmond-Rakerd of the University of Michigan, lead author of the study. Recent research has shown that there is overlap between genetic markers linked to Alzheimer’s disease, bipolar disorder, and major depression. While it’s possible that psychiatric medications may be contributing to dementia in the long-term, Richmond-Rakerd is not convinced.
They suspect that the stress caused by a psychiatric disorder may be a greater risk factor than chronic stress, which can lead to brain health problems. Both animal and human studies have been conducted. human autopsy studiesChronic stress has been linked to a decrease in neural connections in the brain’s memory centre, the hippocampus. This is where Alzheimer’s disease takes its toll. Steven Arnold, a Harvard University neurologist and dementia researcher, believes that stress causes inflammation and immune dysregulation. This can impact brain connectivity. “If you have fewer connections and synapses to begin with because of stress, then you can’t afford to lose as many with aging before it starts to show up as what we might call dementia.” In other words, people with mental illnesses may have less “cognitive reserve”—brainpower that is sufficiently robust to withstand normal aging without obvious losses of function.
Richmond-Rakerd suggests that vulnerability in this group may be related to their difficulty living healthy, socially and physically. “They might exercise less, or drink alcohol excessively, or have trouble staying socially connected”—all of which increase the risk for dementia. Certain psychiatric disorders can lead to higher than average rates of smoking and less education.
Is it possible to reduce the risk of dementia by using a holistic approach to mental illness treatment? Researchers believe so. Researchers tend to believe so. 2020British-based LancetThe Commission on Dementia Prevention estimated that 4 out 10 cases could have been prevented or delayed if society addressed 12 modifiable risk factor factors. This includes depression, low education, and poor social support. The decline in dementia rates may be due to progress on some of these risk factors. 15 percent per decadeover the last 30 years in high income countries. “We think there are two main reasons: better cardiovascular risk factor control and a big increase in education level,” says Kenneth Langa of the University of Michigan, associate director of The Health and Retirement StudyThis is one of the most important efforts to track these trends.
Langa and other researchers agree that it would be ideal if dementia prevention efforts began in childhood, with strong investments in education, and in healthy habits. This would also be applied to the treatment of depression, and other mental illnesses, which often occur in teens and young adults. Unfortunately, this is not the ideal world. Mental illness continues to be stigmatized. However, considering the high costs of both dementia and mental illness, it is difficult to see a better investment.