The difference between a movement along a demand curve and a shift of demand curve is in why thy occur. A movement along the demand curve is a simple change in the price of the good. For example if a DVD costs $1 and then drops to $0.50, the point on the curve has now moved towards the lower right.
The average age of menopause is 51 years old. But there is no way to predict when an individual woman will have menopause or begin having symptoms suggestive of menopause. The age at which a woman starts having menstrual periods is also not related to the age of menopause onset. Most women reach menopause between the ages of 45 and 55, but menopause may occur as earlier as ages 30s or 40s, or may not occur until a woman reaches her 60s.
A woman is said to be in menopause after she has gone for one full year without periods. While most women in the United States go through menopause around the age of 51, a small number will experience menopause as early as age 40 or as late as their late 50s. Rarely, menopause occurs after age 60. When menopause is diagnosed before age 40, it is considered to be abnormal or premature menopause.