There are cases, however, in comparatively young persons where a combination of certain ill-defined symptoms gives a clue to the underlying pathologic processes. These symptoms of early arteriosclerosis are the result of slight and variable disturbances in the circulation of the various organs. Normally there are frequent changes in the blood pressure in the organs, but the vasomotor control of normal elastic vessels is so perfect that no symptoms are noted by the individual. When the arteries are sclerosed, they are less elastic and the blood supply is, therefore, less easily regulated. At times symptoms occur only after effort. The patient may tire more readily than he should for a given amount of mental or bodily exercise; he is weary and depressed, and occasionally there is noted an unusual intolerance of alcohol or tobacco. Vertigo is common, especially on rising in the morning or in suddenly changing from a sitting to a standing position. Some complain of constant roaring or ringing in the ears. There may be dull headache that the accurate fitting of glasses does not alleviate. Unusual irritability or somnolency with a disinclination to commence a new task may be present. Sometimes the effort of concentrating the attention is sufficient to increase the headache. This has been called "the sign of the painful thought." Numbness and tingling in the hands, feet, arms, or legs are also complained of, and neuralgias, not following the course of the nerves but of the arteries, also occur. It is important to remember that the train of symptoms resembling neurasthenia in a person over forty-five years old may be due to incipient arteriosclerosis. This tardy neurasthenia frequently accompanies cancer, tuberculosis, diabetes, and incipient general paralysis, as well as incipient arteriosclerosis.