Finding the perfect temperature is important for more than just feeling comfortable in your home. It turns out that setting the thermostat just right could be the key to preventing dementia later in life.
After following dozens of people aged 65 and older for a year, Harvard researchers found that a temperature between 68 degrees Fahrenheit and 75 degrees Fahrenheit (20ºC to 24ºC) was best for maintaining brain health.
Outside this range, the risk of attention problems doubled with a change of 7 degrees Fahrenheit in either direction.
They said older adults whose homes were in the ideal range were less likely to self-report that they could concentrate than those whose homes were warmer or colder.
The researchers said their results could be especially meaningful as the climate changes.
They said: ‘Our results suggest that even under the current climate, a significant proportion of older adults experience indoor temperatures that are detrimental to their cognitive skills.
‘Climate change could worsen this problem, especially among low-income and disadvantaged older people. Addressing this issue in public health and housing policy is essential to building climate resilience in this vulnerable population.”
Researchers found that a temperature between 68 degrees Fahrenheit and 75 degrees Fahrenheit was ideal for brain function (stock image)
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In a cold house, the scientists say, lower temperatures cause blood vessels to constrict, restricting blood flow to the brain — something that can increase the risk of dementia, which currently affects about 8 million Americans.
Lower temperatures can also cause the body’s cells to work harder as they try to maintain temperatures. Over time, cells become less efficient, meaning less energy is available to brain cells.
In warm homes, the team suggested, the heat can cause excessive sweating and dehydration – which can damage the brain and therefore increase the risk of dementia.
Other experts have suggested that a warm house can 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 directly caused cognitive decline.
Another limitation of the study was that cognitive decline was self-reported, or told to researchers by participants, and not confirmed through a clinical test.
For the study, researchers from Harvard’s Hinda and Arthur Marcus Institute for Aging Research followed 47 adults in Boston, Massachusetts.
They each had a sensor installed in the room of their house where they spent the most time to monitor the temperature in the house over the course of a year.
Participants were also asked to complete questionnaires several times a week about whether they had difficulty concentrating.
The adults recruited were on average 79 years old and the vast majority – 80 percent – were women, in whom the incidence of dementia is more common.
The study began in October 2021 and concluded in March 2023.
The findings build on previous research that shows sleep is most efficient — a key factor in warding off dementia — for older adults when temperatures hover between 68 and 77 degrees Fahrenheit.
Dr. Amir Baniassadi, a brain health expert and lead author of the study, said: ‘Our findings underline the importance of how environmental factors such as indoor temperature influence the cognitive health of 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 to protecting their cognitive well-being.’
In the US, approximately 514,000 people are diagnosed with dementia each year, but researchers estimate that this number could rise to 1 million people per year by 2060 due to the increasingly aging US population.
A recent study found that this is consistent with almost one in two Americans developing dementia at some point in their lives.