Millions more Americans may be at risk of memory-robbing dementia than previously thought, a study has suggested.
As 7 million Americans live with dementia – a figure that’s expected to double by 2050 – research is increasingly homing in on the lifestyle tweaks that could stave off the disease.
One recent study found nearly half of dementia cases are tied to lifestyle factors such as high blood pressure, smoking, obesity and type 2 diabetes.
Now, after following almost 300,000 Americans for two years, researchers at Boston University have found people living with type 1 diabetes were nearly three times more likely to develop dementia than those without the condition.
Type 2 diabetes doubled the risk of dementia, suggesting type 1 diabetes was a greater risk factor.
While type 2 diabetes is preventable and is caused by lifestyle factors such as obesity and poor diet, type 1 is a non-preventable autoimmune condition in which the body destroys its own insulin-producing cells.
Type 2 is most often diagnosed in older adults, while type 1 usually develops in childhood. The CDC also estimates 90 to 95 percent of the 40 million diabetes cases in the US are type 2, making type 1 far less common.
However, that still leaves 2 to 4 million Americans with type 1 diabetes who may be prone to dementia later in life. Type 1 diabetes diagnoses are also on the rise by about three to five percent per year, which experts suggest could be due to environmental pollutants and better detection.
People with type 1 diabetes may be nearly three times more likely to develop dementia than those without the condition, a new study suggests (stock image)
‘As advances in medical care have extended the lives of people with type 1 diabetes, it’s becoming increasingly important to understand the relation of type 1 diabetes to the risk of dementia,’ Jennifer Weuve, study author and professor in the Department of Epidemiology at the Boston University School of Public Health, said.
‘We have known that type 2 diabetes is linked to an increased risk of dementia, but this new research suggests that, unfortunately, the association may be even stronger for those with type 1 diabetes.’
It’s unclear exactly how type 1 diabetes raises the risk of dementia, but experts believe repeated bouts of low and high blood sugar may trigger inflammation and cell damage in the brain’s memory center, the hippocampus.
It may also be because type 1 diabetes involves severe insulin dysfunction, which may starve neurons of glucose and allow amyloid plaques associated with dementia to accumulate.
Blood sugar spikes and drops can also damage blood vessels in the brain, leading to vascular dementia.
Type 2 diabetes is well known to damage the brain’s blood vessels, trigger inflammation and cause amyloid to build up.
The new study, published in Neurology, looked at 283,772 participants with an average age of 65. Most dementia patients in the US are diagnosed after age 65. About 57 percent were women, and 60 percent were white. The average follow-up time was about two years, but patients were followed for up to six years.
Of the participants, 5,442 had type 1 diabetes while 51,511 had type 2. During the follow-up period, 2,348 people developed dementia, including 144 type 1 diabetes patients, or 2.6 percent, and 942, or 1.8 percent, with type 2 diabetes.
Jana Nelson was 50 when diagnosed with early onset dementia, following severe personality changes and a sharp cognitive decline that left her unable to solve simple math problems or name colors
The team found that compared to those without diabetes, patients with type 1 were 2.8 times more likely to develop dementia, and people with type 2 disease were twice as likely. These estimates took socioeconomic factors such as age and education level into account.
‘Our findings advance the existing evidence that [diabetes] is related to higher risk of dementia,’ the researchers wrote. ‘Despite the vast evidence amassed, there remains a need to evaluate dementia risk by [diabetes] type.’
In addition to a recent study that found half of dementia cases are tied to lifestyle factors, the new findings also build on previous research published in The Lancet, which identified 14 modifiable risk factors for dementia, including physical inactivity, smoking, diet, pollution and lack of social contact, among others.
However, type 1 being associated with a greater risk than type 2 poses concern to researchers, as type 1 is not preventable.
‘Type 1 diabetes is not common, so this condition accounts for a small fraction of all dementia cases. But for the growing number of people with type 1 diabetes who are over 65 years old, these findings underscore the urgency of understanding the ways in which type 1 diabetes influences dementia risk and how we can prevent or delay it,’ Weuve said.
