Dementia is the significant loss of intellectual abilities such as memory capacity which is severe enough to interfere with social or occupational functioning. Criteria for the diagnosis of dementia include impairment of attention, orientation, memory, judgment, language, motor and spatial skills, and function.
Alzheimer's disease is the most common cause of dementia. Dementia is not a natural part of ageing, although most people with dementia are older. After the age of 65 the likelihood of living with dementia doubles every five years and it affects 24% of those aged 85 and over.
In 2004 a study conducted by researchers at the Tufts-New England Medical Centre, Boston, USA on the effect of tai-chi on health outcomes in patients with chronic conditions: a systematic review was published in Archives of Internal Medicine. Six studies investigated the psychological effects of Tai Chi.
Results from two trials indicated that older adults who participated in a Tai Chi exercise program showed demonstrably better scores on indices that measured depression, psychological distress, and positive well-being. A non-randomised, controlled study, meanwhile, showed that patients with multi-infarct dementia or Alzheimer's disease who participated in twice-weekly Tai Chi sessions for 7 weeks demonstrated "thinking that was focused and insightful, beyond the level normally manifested for this group of participants."