Dreams may be predictive of health outcomes in the long run. Having regular nightmares in childhood may be linked to the development of cognitive impairment or Parkinson's disease later on.

For the new study, which was published in The Lancet's journal eClinicalMedicine, a clinical fellow at the University of Birmingham, Abidemi Otaiku, looked at data from a group of nearly 7,000 children who were a part of the 1958 British Birth Cohort Study.

The idea was to find out whether having a lot of bad dreams in childhood may be associated with the development of cognitive impairment and Parkinson's disease later on.

A previous study has shown that frequently having distressing dreams in middle and older adulthood may be associated with increased risks for such conditions later in life. But whether a similar association is present with childhood nightmares has yet to be evaluated.

"Given that a large proportion of people who experience regular nightmares as adults also report having had regular nightmares when they were children, this made me wonder whether having lots of bad dreams during childhood might predict the development of dementia or Parkinson's disease later in life," Otaiku noted in a piece on The Conversation.

The 1958 British Birth Cohort Study followed the lives of children in England, Scotland and Wales, who were born in the week of March 3 to 9, 1958. In it, the mothers answered some questions about their kids' health at ages seven and 11. This includes whether the children had bad dreams in the three months prior.

He found that those who had persistent bad dreams had 85% increased risks of developing cognitive impairment or Parkinson's disease by age 50 compared to those who didn't.

"The results were clear," Otaiku said in the piece. "The more regularly the children experienced bad dreams, the more likely they were to develop cognitive impairment or be diagnosed with Parkinson's disease."

"Therefore, the present study is consistent with, but also extends these prior findings, by demonstrating that distressing dreams which occur during childhood, may also be associated with future dementia and PD," he further stated in the study.

Further studies are needed to confirm the findings, Otaiku said, noting a possible genetic connection — a particular gene known to up the risk of having nightmares regularly that's also linked to increased risks for Alzheimer's disease in older age. It's also possible that the disturbed sleep due to nightmares may be playing a part in the possible connection.

Still, the results shouldn't be a cause for alarm, Otaiku said, as only a small percentage of the population ended up developing cognitive impairment or Parkinson's Disease.

Future studies could dive deeper into a possible causal relationship between nightmares with dementia and Parkinson's disease. If proven true, then this could open hopeful avenues of possibly helping to prevent the development of the disease in the future by finding ways to treat the nightmares.