People with a history of a neurological or psychiatric condition – or who are currently living with one – may be at an increased risk of developing a second condition in the future, according to a recent study.
Experts from the University of Waterloo and the Institute for Clinical Evaluative Science also found that sex plays a role in that risk, meaning men and women have different chances for developing a later condition after experiencing an earlier one.
Colleen Maxwell, the lead author of the study and a professor at the School of Pharmacy at Waterloo, told Seasons the study was conducted in Ontario and is the largest in terms of population size and study time period.
Maxwell and her colleagues analyzed data from more than five million Ontario residents between the ages of 40 to 85 and followed them over 14 years. They primarily examined the relationships between common neurological conditions, including dementia, Parkinson’s disease and stroke, as well as psychiatric disorders, such as depression and anxiety.
The researchers looked at the links between these conditions and investigated how a previous experience, such as stroke, could increase the risk of other conditions in the future, like the risk of dementia and vice versa. In almost all cases, the rate of developing a second condition increased.
According to the study, people who were previously diagnosed with Parkinson’s were found to have four times the risk of developing dementia in the future. Those with a prior stroke had more than double the risk of developing dementia. In terms of psychiatric disorders, those with a history were associated with a higher risk of developing dementia later in life. For other conditions, Maxwell said the risk of developing a second disorder remained for 10 years or more after the first.
The reason for the correlation isn’t exactly known, but the researchers hypothesized that biological pathways and mechanisms exist between these conditions that link them together.
The reason for the correlation isn’t exactly known, but the researchers hypothesized that biological pathways and mechanisms exist between these conditions that link them together.
“For example, as an individual with Parkinson’s disease progresses and that’s a neurodegenerative condition, it gets worse,” she said. “Many of them will get dementia simply because of the biology and the progression of the disease. As one disease progresses, the deficits progress, which leads to a second condition. That’s very common with people with Parkinson’s who are seen to later develop dementia.”
She added that genetic makeup, environmental exposures and other factors, such as heart disease, high blood pressure, high cholesterol, smoking and obesity can also be potential reasons for the connection.
“The other thing is if someone is starting to experience the early signs and symptoms of a disorder like dementia, they become aware of any kind of related limitations of the disability, and have a psychological reaction to that,” Maxwell said. “They can become depressed because they are aware of the progressive decline in their memory function.”
Risk different for women and men
The study also revealed the risk of developing a future condition after experiencing an earlier one depends on gender. For example, researchers said when they evaluated those who experienced a stroke earlier in life, women were much more likely than men to develop dementia later in life.
Maxwell said the complex interaction of genetics, hormones, risk factors, and psychological risk factors could all be reasons why sex influences a potential association of a second condition.
“We also found that for some of the conditions, women with a prior condition compared to males were more likely to have a later mood or anxiety disorder,” she said. “It’s common in the literature to see things like depression being more common among women, and some of that is related to genetic hormones, something that’s unique about the lifestyle risk factors of the course of their own life.”
How to take action
With these findings, Maxwell and her team hope people can take preventive measures to avoid certain health conditions from developing in the first place, but also to help improve care for people who may already be suffering from neurological or psychiatric conditions.
For people without these conditions, focusing on modifiable lifestyle risk factors linked to many conditions can potentially decrease the risk of developing them in the future.
For people without these conditions, focusing on modifiable lifestyle risk factors linked to many conditions can potentially decrease the risk of developing them in the future.
“The more we can do early on in life to address and prevent high blood pressure, high cholesterol, high blood lipids, avoid smoking, deal with diabetes, obesity, and also heavy alcohol use … then we can certainly avoid the sequence of events that we’re seeing on our data,” she said.
But for people who may already have certain health conditions or disorders, Maxwell hopes the information from the study can improve and manage overall care to help prevent a second condition from forming, as well as avoid progression of current conditions.
“We need to do everything possible to be aware that these conditions can cluster together and can make care more complex,” she said. “That should be recognized, detected and managed appropriately because conditions can worsen each other over the course of someone’s life. And so all of this leads to maximizing their care, appropriateness of their care and ultimately their quality of life and outcome.”
