Does frequent mobile phone use increase the risk of brain tumours?
With normal use, the research shows no increased risk of brain tumours; with more than ten years of use there are weak indications of a slightly elevated risk, but the evidence is insufficient to base behavioural changes on.
With normal, everyday mobile phone use, multiple large studies show no increased risk of brain tumours. A Norwegian study of patients with glioma, meningioma and acoustic neuroma actually found lower risk figures than expected. Nine studies combined, covering more than 5,000 cases and over 12,000 comparison individuals, produced a pooled risk figure of 0.90, which is below 1.0. That points to no demonstrable increased risk.
The picture becomes somewhat more complicated for people who have been making regular calls for ten years or longer. A meta-analysis of 23 studies with more than 37,900 participants found no effect with short-term use (risk figure 0.98), but a slightly elevated risk with ten or more years of use (risk figure 1.18). Another meta-analysis of nine studies reported a risk figure of 1.25 with long-term use, but the authors themselves stressed that this result is uncertain and requires confirmation.
A Finnish analysis of 99 gliomas found slightly more tumours on the side of the head where people hold their phone, but there was no clear relationship with the amount of use. The researchers described this as methodologically interesting, but insufficient for firm conclusions. A well-known pitfall in this type of research is recall bias: people with a tumour may remember their phone use differently from people without a tumour.
Importantly, one study on this topic was officially retracted by the journal in 2013 and must not be used as evidence. The remaining, independent studies taken together present a consistent picture for short-term use. For use of ten years or longer there are preliminary indications of a slightly elevated risk, but cause and effect have not yet been established.
This answer draws on multiple studies, including two meta-analyses that pool dozens of studies and thousands of participants, as well as additional national studies from Sweden, Norway, Japan and Finland. The researchers behind the meta-analysis on long-term use themselves stressed that prospectively designed studies are needed for more reliable statements about cause and effect. A frequently cited flaw is recall bias, and the studies measure associations, not causality. The evidence for short-term use is reasonably solid; for long-term use (10 years or more) it is rather thin and contradictory.
Does hearing loss increase your risk of dementia, and does a hearing aid help?
Hearing loss demonstrably increases the risk of dementia, and a hearing aid appears to help, but proven protection for everyone has not yet been established. Have hearing loss assessed in any case, if only because of the other health risks associated with it.
Does heading the ball frequently in football, or sustaining a concussion, increase my risk of dementia later in life?
Professional footballers who head the ball frequently have a considerably higher risk of dementia than goalkeepers or people without an elite sporting background. The same applies after a concussion involving memory loss.
Does years of insufficient sleep damage your brain?
Years of insufficient sleep damages the brain through multiple pathways at once, and some of that damage appears difficult or impossible to reverse. Make sure you consistently get enough sleep, and have sleep apnoea treated if you have symptoms of it.
Which lifestyle habits protect your brain health over the long term?
Cognitive activities, a plant-based dietary pattern, and regular exercise, preferably in combination, offer the best-supported protection for your brain over the long term. Hard cause-and-effect evidence is still lacking, but the associations are broad and consistent enough to take seriously.
Do your brains really shrink as you get older?
Your brain does indeed shrink with age, particularly in areas involved in memory and planning. High blood pressure accelerates that process, while exercise and cognitive effort strengthen your brain's compensatory activity.
What does smoking do to your brain as you age?
Smoking accelerates brain ageing and increases the risk of dementia. Quitting smoking is one of the best-supported steps you can take to keep your brain healthy for as long as possible.