Walking slowly may be an early sign of Alzheimer's in older people at risk of dementia, research suggests.
Scientists studied 128 people with an average age of 76 who had displayed evidence of impaired memory.
Scans showed that 48% of the group had a build up of beta amyloid protein fragments in their brains - one of the hallmarks of Alzheimer's disease.
These individuals were also more likely to walk at a slower speed, measured using a standard test that times how fast a person can cover 13 feet at normal pace. The average walking speed was 3.48 feet per second.
Lead researcher Dr Natalia del Campo, from Toulouse University Hospital in France, said: "It's possible that having subtle walking disturbances in addition to memory concerns may signal Alzheimer's disease, even before people show any clinical symptoms."
The findings are published in the latest online issue of the journal Neurology.
Dr Louise Walker, research officer at Alzheimer's Society, said: "Memory problems are the most recognisable symptom of Alzheimer's disease but the condition can also affect people in many other ways, such as problems with navigation or concentration.
"Research has already shown that people with Alzheimer's disease may have difficulties with walking - but it is unclear if this is due to the condition itself or other factors, especially those associated with ageing.
"More long-term research is needed to determine whether a build-up of the protein amyloid, which is one of the hallmarks of Alzheimer's disease, directly leads to slower walking and whether this could form a suitable part of a clinician's diagnostic process."