Alzheimers disease is marked by changes in memory, language and behaviour, however there's an increasing awareness of changes in mobility and its' correlation to cognitive decline. Having worked in dementia units of aged care facilities, I've seen the gradual changes in people's walking abilities. What starts off as a change in gait and stride, can over time lead to missteps, imbalance and falls, increased falls and then the reliance on tub chairs and wheel chairs for mobility. Part of the story of what helps us to maintain balance involves the vestibular system of the inner ear. This is made up of three semicircular canals, a saccule and utricule, all of which are attached to the cochlea. These three structures, all have tiny hairs (stereocilia) that play a big part in motion detection. These layers of micro hairs within the three structures are arranged in bundles and poke out into an internal gelatinous liquid (endolymph). When this liquid moves, in either of the three structures in response to head and/or body movement, the tiny hair cells bend and send nerve signals to our brain to tell us how to auto correct to find balance.
With Alzheimer's Disease, balance is impaired, not by actual deterioration or damage to the vestibular system but by the inability to access neuronal information. Neuronal information is inaccessable as neurofibrillary tangles and plaques in the brain of people with Alzheimer's, serve as a barrier to slowing down and eventually blocking the information needed to make readjustments to posture to find balance in movement and gait. But that's just one part of a bigger picture.