Abstract
It has been shown 1 that the electrical impedance per unit area of the skin may deviate from normal values not only in thyroid and other endocrine conditions but also in disturbances involving the autonomic and central nervous systems. Gross changes in skin capacity have been reported in certain types of mental disease. 2 It appeared to be of interest, therefore, to study a group of mental patients with a view to determining whether or not changes in the impedance properties of the skin could be found.
Impedance determinations were made by the 3-electrode method at 11,160 c.p.s., using a concentric and a disc electrode applied over the region of the biceps and triceps as described elsewhere. 1 , 3
The patients were not selected in any way and included all of the females (54) in the adult wards at the N. Y. State Psychiatric Institute. This group was composed predominantly of schizophrenics and psychoneurotics. The average age was 29 years.
A histogram of the results obtained is shown in Fig. 1 (dotted lines) and represents the distribution of the mean impedances of two 6 cm 2 skin areas measured on the anterior and posterior sides of the upper right arm. A corresponding histogram of the results obtained on 102 normal females in a previous investigation 1 (solid lines) is given for purposes of comparison.
As will be seen from Fig. 1, there is a considerable shift of the mentally diseased group toward low values, their mean impedance m falling well to the left of the normal mean M. The group of patients having impedances lying entirely outside the normal histogram on the low side are of particular interest since it is in this low impedance region that the values for thyrotoxics fall. 1 None of the patients in this low impedance group showed signs of thyrotoxicosis.
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