Dementia in a person in their thirties is rare, but a new study has uncovered a surprising pattern.
Younger adults with severe mental illness were far more likely to have dementia than people of the same age without a psychiatric diagnosis.
The study also found an increased risk of stroke, particularly during early and middle adulthood. Researchers say the results show why physical health should be treated as an important part of mental health care from a much younger age.
The research used medical information from nearly 700,000 people living in Catalonia, Spain. This included around 177,000 people with schizophrenia, bipolar disorder or major depression and approximately 517,000 people without a recorded psychiatric condition.
Severe mental illnesses affect hundreds of millions of people worldwide. Although they are mainly diagnosed and treated because of their effects on mood, perception, behavior and thinking, they are also associated with poorer physical health and shorter average life expectancy.
Scientists have known for years that heart and blood vessel disease is more common among people with some psychiatric conditions. The new study asked whether differences in dementia and stroke could already be seen at different stages of adulthood.
The researchers compared people between the ages of 20 and 99. Rather than looking only at older adults, they examined the relationship between severe mental illness, dementia and stroke separately across different age groups.
The most eye-catching result appeared among people aged 30 to 39. Those with severe mental illness had more than 20 times the odds of dementia compared with people of the same age who did not have a psychiatric diagnosis.
That number needs careful explanation. Dementia remained very rare in both groups, despite the large difference in relative odds.
Among every 100,000 people aged 30 to 39 without severe mental illness, about 24 had dementia. Among those with severe mental illness, the number was approximately 550 per 100,000.
This means about 0.55% of younger adults with severe mental illness had dementia compared with about 0.02% of the comparison group. The finding is unusual enough to deserve attention, but it does not mean that dementia is common among young people with psychiatric conditions.
The association continued into older age. Among people aged 80 to 89, those with severe mental illness still had about four times the odds of dementia.
Dementia occurs when changes or damage in the brain seriously interfere with memory, reasoning and everyday independence. It becomes much more common with advancing age, although younger people can occasionally develop it.
The researchers also found an important pattern for stroke. Adults aged 40 to 49 with severe mental illness had almost three times the odds of ischemic stroke compared with people without a psychiatric diagnosis.
Ischemic stroke happens when a blood clot blocks an artery carrying blood to the brain. The affected brain tissue loses oxygen, and rapid treatment is needed to limit damage.
Why might psychiatric illness be connected with these conditions? There is unlikely to be one simple explanation.
People with severe mental illness may have higher rates of some known risk factors for stroke and dementia. These can include smoking, obesity, diabetes, high blood pressure, physical inactivity and problems with sleep.
Long-term stress and social disadvantage may also affect health. Some people with serious psychiatric conditions face unemployment, poverty, isolation or difficulties receiving consistent medical care, all of which can influence long-term health.
Medicines are another part of the picture. Some psychiatric drugs can contribute to weight gain or changes in blood sugar and cholesterol, although these medicines may also be essential for preventing severe symptoms, relapse or hospitalization.
None of these explanations was proven by the new study. Researchers will need further work to understand how much each factor contributes and whether some biological processes are shared between mental illness, blood vessel disease and cognitive decline.
The findings suggest that health services should not separate the mind from the rest of the body. Someone receiving treatment for schizophrenia, bipolar disorder or major depression may also benefit from careful monitoring of cardiovascular and neurological health.
This could include routine checks of blood pressure, cholesterol and blood sugar. Helping people stop smoking, remain physically active and receive treatment for other medical conditions could also reduce risks that can be changed.
Brain health deserves attention too. Problems with memory, concentration and planning are already known to affect many people with schizophrenia and substantial numbers of people with bipolar disorder or major depression.
Professor Kamilla Miskowiak of the University of Copenhagen, who independently commented on the research, said cognitive health should be considered an important part of treatment. She was not involved in conducting the study.
The researchers themselves emphasized that their results do not show that mental illness causes dementia or stroke. The study took a snapshot of existing medical records rather than tracking people from diagnosis through later life.
This type of research is useful for finding patterns across very large populations. However, it cannot determine which condition appeared first in every case or fully separate the effects of lifestyle, medicines, income, education, medical care and other health problems.
Future studies will follow individual patients over time. Researchers hope this will reveal when the increased risks develop and whether earlier prevention can reduce them.
The study involved researchers including co-lead author Dr. Michele De Prisco from Hospital Clínic-IDIBAPS and the University of Barcelona. The findings were published in European Neuropsychopharmacology.
The huge number of medical records is a major strength because it allowed the researchers to examine uncommon conditions such as dementia in younger adults. At the same time, the cross-sectional design means the 20-fold difference should be interpreted as an association rather than evidence that severe mental illness directly produces dementia.
The study therefore should not create the impression that a young person with depression, bipolar disorder or schizophrenia is likely to develop dementia. The absolute risk at younger ages remained low, even among people with severe mental illness.
Its more useful message is about prevention. If people with serious psychiatric conditions face higher physical and brain health risks earlier in life, doctors may have an opportunity to identify and treat some of those risks long before old age.
Better coordination between mental health care and general medical care could therefore be important. Treating psychiatric symptoms while also protecting the heart, blood vessels and brain may improve both quality of life and long-term health.
Source: University of Barcelona
