Harvard researchers reveal exact temperature to set the thermostat to ward off dementia

Finding the perfect temperature is important for more than just being comfortable in your home. It turns out, setting the thermostat just right could be key to warding off dementia later in life. 

After tracking dozens of people 65 and older for one year, Harvard researchers found a temperature between 68 degrees Fahrenheit and 75 degrees Fahrenheit (20C to 24C) was best for maintaining brain health.

Outside of this range, the likelihood of experiencing attention difficulties doubled with a 7-degree Fahrenheit change in either direction.  

They said older adults whose homes were in the ideal range were less likely to self-report difficulty concentrating than those whose homes were hotter or colder.   

The researchers said their results could prove especially meaningful as the climate changes.

They said: 'Our results suggest that even under the current climate a considerable portion of older adults encounter indoor temperatures detrimental to their cognitive abilities. 

'Climate change may exacerbate this problem, particularly among low-income and underserved older adults. Addressing this issue in public health and housing policy is essential to building climate-resiliency in this vulnerable population.'

In a cold home, the scientists said, lower temperatures cause blood vessels to constrict, which limits blood flow to the brain - something that can increase the risk of dementia, which currently affects about 8million Americans.

Cooler temperatures also may cause the body's cells to work harder as they try to maintain the its temperature. Over time, cells become less efficient, meaning there is less energy available for brain cells.

In hot homes, the team suggested, the heat could cause excess sweating and dehydration — which can damage the brain, therefore raising the risk of dementia.

Other experts have suggested a hot home could also disrupt sleep - and poor sleep is known to be a major risk factor for dementia.

However, researchers acknowledged that the study was observational and could not definitively prove whether shifts in home temperature were directly causing cognitive decline.

Another limitation of the research was that cognitive decline was self-reported, or told to researchers by participants, and not confirmed via a clinical test.

For the study, researchers from Harvard's Hinda and Arthur Marcus Institute for Aging Research, tracked 47 adults in Boston, Massachusetts.

Each had a sensor installed in the room of their house where they spent the most time to monitor home temperature over the course of a year.

Participants were also asked to fill in questionnaires multiple times a week on whether they were having trouble concentrating.

Adults recruited were 79 years old on average, and the vast majority — 80 percent — were female, who have a higher incidence of dementia. 

The study began in October 2021, and was completed by March 2023.

Its findings build on previous research that sleep is most efficient - an important factor for warding off dementia - for older adults when temperatures hover between 68 and 77 degrees Fahrenheit. 

Dr Amir Baniassadi, a brain health expert and study lead author, said: 'Our findings underscore the importance of how environmental factors like indoor temperature, impact cognitive health in aging populations.

'This research highlights the need for public health interventions and housing policies that prioritize climate resilience for older adults.'

He added: 'As global temperatures rise, ensuring access to temperature-controlled environments will be crucial for protecting their cognitive well-being.'

In the US, about 514,000 people are diagnosed with dementia every year, but researchers estimate this number could surge to 1million people a year by 2060 because of America's increasingly aging population.

A recent study found this was the equivalent to nearly one in two Americans developing dementia at some point in their lifetime.