Changes in body temperature.
People over the age of 60 have, on average, a lower temperature than the accepted 'normal' value of 37°C. There is also less variability in temperature, which means that older people may have little fever response to severe infection. People with cognitive impairment may have either higher or lower temperature; this may be due to loss of appropriate behavioural response to changes in temperature. Those with Alzheimer's disease sometimes have a modest increase in core body temperature, suggesting that change in basic metabolic rate may be responsible.