The same phenomena occur also after the administration of thyroid
extract in large doses to normal subjects. In the course of
sexual activities there is an increased action of the thyroid,
which is indicated by an increase in its size and vascularity.
That in fear and in injury the thyroid, in cases of Graves'
disease, is probably stimulated to increased activity is indicated
by the increased activity of the thyroid circulation, by an increase
in the size of the gland, by the histologic appearance of activity
in the nuclei of the cells, and by an increase of the toxic symptoms.
Finally, Asher has stated that electric stimulation of the nerve supply
of the thyroid causes an increased secretion. The origin of many cases
of Graves' disease is closely associated with some of the causes
of the discharge of nervous energy, depressive influences especially,
such as nervous shocks, worry and nervous strain, disappointment in love,
business reverses, illness and death of relatives and friends.
The association of thyroid activity with procreation is well known,
hence the coincidence of a strain of overwork or of fear with
the sexual development of maturing girls is obviously favorable
to the incidence of Graves' disease. The presence of a colloid goiter
is a suitable soil for the development of Graves' disease, and I
fully recognize also the evidence that infection or auto-intoxication
may be contributing factors and must be assigned their role.

I have never known a case of Graves' disease to be caused by success
or happiness alone, or by hard physical labor unattended by
psychic strain, or to be the result of energy voluntarily discharged.
Some cases seem to have had their origin in overdosage with thyroid
extract in too vigorous an attempt to cure a colloid goiter.
One of the most striking characteristics of Graves' disease is
the patient's loss of control and his increased susceptibility