A Swedish study involving military men identifies nine risk factors, many of which may be preventable for adolescents, that are associated with young-onset dementia - dementia diagnosed before the age of 65.

The study, which was published online by JAMA Internal Medicine, followed 488,484 Swedish men who enlisted in mandatory military service between 1969 and 1979. The men had an average age of 18 at the time of enlistment.

After a 37-year follow-up, researchers found that 487 men had young-onset dementia (YOD) at an average age of 54. Results from the study show that the major risk factors associated with the early-onset disease included:

  • Alcohol intoxication
  • Stroke
  • Use of antipsychotics
  • Depression
  • Father's dementia
  • Drug intoxication
  • Low cognitive function at enlistment
  • Low height at enlistment
  • High systolic blood pressure at enlistment.
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The researchers note that the factors listed account for 68% of the young-onset dementia cases they identified. Additionally, men who had at least two of the nine risk factors who were also in the lowest third of cognitive function had a 20-fold increased risk for YOD, they say.

Because most of the risk factors were "potentially modifiable" and "could be traced to adolescence," the researchers say that there are "excellent opportunities for early prevention."

Impact of preventing dementia

The study's authors stress that dementia is a concern felt everywhere, with an estimated 35.6 million people suffering from the condition worldwide. They say the costs associated with dementia will likely increase over the next 40 years, as over 115 million people are expected to be diagnosed with it by 2050.

There are currently around 200,000 Americans under 65 years of age with young-onset dementia, the study notes.

In a commentary on the study, Dr. Deborah Levine from the University of Michigan Health System, Ann Arbor, says:

"More Americans may develop YOD because of increases in traumatic brain injury among young veterans and stroke among young black and middle-aged adults. We must have effective and humane strategies to care for patients with YOD and their families."

Researchers from the study say that because YOD has been related to genetic mutations within families affected by the condition, knowing which risk factors contribute to this type of dementia could help them better understand how to prevent it.

A 2011 study published in The Lancet Neurology suggests half of Alzheimer's and dementia cases may be preventable, listing the following preventable or treatable risk factors: