Find a mistake in each line and correct it. Experts emphasize that senility is not an inevitably result of ageing process, like graying hair. It is a specific disease with a various of causes, resulting in failing memory, a decline in the ability to work with numbers, error in judgment, and irritability often leading to Paranoia. By their 70s, many normal people show any decline in memory, reasonable, learning and problem-solving, but others do not. Older people with a good deal of education which are used to using their minds appear to have less difficulty. Moreover, about 15-20 per cent of patients who becomes senile suffer from conditions that can be correct.