Exercising twice a week help stave off progression to dementia in older people already showing signs of cognitive decline, scientists say. The study found that regular resistance training, such as using a rowing machine or weights, can also improve attention, memory and problem solving, the Daily Express reported. Eighty-six women, aged 70 to 80 with mild cognitive impairment were followed for six months. Brain scans after aerobic and resistance exercise were taken. Teresa Liu-Ambrose, from the University of British Columbia, said brain function had improved. The results are in the Archives of Internal Medicine.