CHANGES WITH AGING 



429 



AGE 



Figure 5. Age and the logarithm of the frequency of severe atherosclerosis. 

 The lines on the graph are parallel, with the slope proportional to the 

 square of the age beyond 15 years. 



the average frequency of severe coronary atherosclerosis are plotted 

 against age for the mid-decade ages of 35, 45, and 55. Below the thirties 

 we lack adequate data; above the fifties the effect of losses from the 

 population by death may produce a serious bias. But over this range 

 the points indicate two lines with the same slope. The lines on the 

 graph were drawn with parallel rulers, setting the slope to correspond 

 with the square of the age minus 15 years. In other words, the data 

 indicate that from the end of puberty until the beginning of old age 

 the progression of atherosclerosis is proportional to the square of the 

 duration of exposure. 



But what about the great difference between the Japanese and the 

 Minnesotans in the general level of these lines? Is this related to the 



