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THE CORRELATION BETWEEN MENTAL DEFECT AND ANOMALIES OF THE HARD PALATE.'
By IRENE CASE, UNIVERSITY OF Chicago. In order to determine whether a correlation exists between mental defect and defects of the hard palate, it is necessary to make casts of the palates of a great many normal and abnormal individuals in order to compare them in a definite and specific way. The only published work along this line is that of Channing and Wissler (1), 1905.
But ever since 1600 it has been recognized that a deformed palate is very frequently present in the feeble-minded. The frequency of the pathological palate has been testified to by many investigators. Church and Peterson (2) say: “The frequency of the pathological palate among marked degenerates, such as the insane, idiots and epileptics has been stated by many investigators. Talbot reported 43% of abnormal palates in 1605 inmates in institutions for the feeble-minded. Ireland makes it nearer 50%. Charon found abnormal palates in 10% of apparently normal persons, in 82% of idiots and feeble-minded, in 76% of epileptics, 80% in cases of insanity in general, 70% in the hysterical insane, and 35% in cases of dementia paralytica.”
Ireland (4) says: “As an accompaniment of genetous idiocy the palate is narrow, the space between the bicuspids and the molars of the opposite sides being diminished. The height of the palatal arch is at the same time increased at the expense of the cavity of the nares. In most cases of vaulted palate the symmetry of the normal curve of the dental arch is much impaired." However, he decidedly says that "the vaulted palate does not occur in all genetous idiots. In some cases the palate is normal, but undoubtedly the deformity is very common."
Ireland quotes T. S. Clouston as saying in his “ Neuroses of Development" that
*This research was undertaken at the Psychopathic Laboratory of the University of Chicago, under the direction of Dr. H. C. Stevens, to whom the writer offers grateful acknowledgment for advice and assistance in the preparation of this report.
“there are over three times more deformed palates among idiots and congenital imbeciles than amongst the sane. Only one-tenth of the idiot palates are typical, while over two-thirds of them are deformed. Less than one-fifth of the palates of the average population are deformed. A deformed palate is also found to be more frequent with the insane and epileptic than with normal persons." (Edinburgh, 1891.)
Peterson (5) says, “Show me your palate and I will probably be able to tell you whether you belong to the great class tainted by heredity, comprising many insane, imbecile, feeble-minded, epileptic, hysterical, etc., individuals." No doubt this would be considered a highly exaggerated statement at the present time. But that is just our problem: to see if we can truthfully say that all defective palates mean a defective mentality. Or should we take into consideration the growth of the head, i. e., its length, breadth, circumference, etc., as determining to some extent, at least, the size and shape of the palate? Further, in a condition of feeble-mindedness, will not other stigma coexist besides the defective palate, such as cranial anomalies, defects of the heart and lungs, changes in the reflexes of the body, etc.? Is it fair to say that if only a defective palate is present, that feeble-mindedness exists ?
No doubt it would be of great diagnostic value to be able to make such a statement, to know that there was this definite, outward, visible sign of inward disturbance.
Peterson examined 1000 insane, 100 criminals, 600 idiots, and 500 neuropaths (casts were not made) and found asymmetry of the palate very common, and occasionally the only noteworthy peculiarity. This latter fact is to be questioned. Is it not usual to find asymmetry of the face and skull in cases of asymmetry of the palate? May it not be that such asymmetry (or any departure from the normal structure of the palate) is in many cases simply a concomitant of other deviations of the size and shape of the head, etc.
Tredgold (9) says, "The association of abnormalities of the palate with mental deficiency has long been recognized, and there is no doubt that it is one of the commonest malformations occurring in this condition." He quotes Clouston “Neuroses of Development,” 1891, who has recorded a large number of observations which show conclusively that although deformed palates occur in the normal, they are far more frequent in neuropaths and the mentally defective. He states that deformed palates are present in 19% of the ordinary population, 33% of the insane, 55% of criminals, but in no less than 61% of idiots.
Talbot (7) says, “ Langdon Down called the attention of the medical profession to the fact that high vaults, as well as irregularly shaped jaws, were very common among idiots and congenital imbeciles." He says: “My studies prior to 1887 not only show high and contracted arches among sane individuals as well as idiots, but that they also frequently occur among the deaf, dumb, blind, insane, criminal, drunkards, neurotics and degenerates generally. It will be noticed, therefore, that no particular class of individuals is exempt from these deformities. So a high vault is not due to mental weakness.” (But it might be said that all forms of degeneracy mentioned here are manifestations of mental weakness of some sort.)
Talbot (7) quotes Dr. Claye Shaw as saying that "there is no necessary connection between a high palate and the degree of mental capacity of the individual."
Thus we see that there have been advanced arguments both for and against the idea that a defective palate indicates a defective mentality.
In the work of Channing and Wissler, they have concluded from a study of about 1500 casts, 1000 abnormal and 500 normal, that the absolute size of the palate for the three following measurements seems to be the same for feeble-minded as for normal : Width at the canines; width at the molars; and length from the alveolar point to a line connecting the first molars. But they do find a relatively small difference in the variability of these dimensions, the feeble-minded showing greater variation. However, as to the height of the palate, they find that while there is no real difference for adult males, that for children has the character of a real difference. The female children show no such difference, for while the average height for the abnormal is absolutely greater than for the normal, the difference is within the range of accidental deviation from the type.
The present report is upon the measurements of casts obtained from children appearing before the Psychopathic Laboratory of the University of Chicago for examination. The number of casts is as follows:
Male. Female. Total.
The specific measurements to be reported on are the same as those reported by Channing and Wissler, namely:
A. The minimum distance between the first molars, measured horizontally from the bases of the molars.
B. The maximum height of the palate, measured from the plane of the gum line.
C. The distance from the line connecting the two first molars to the alveolar point.
D. The distance between the canines, measured horizontally from their bases.
In addition to these four measurements, any asymmetry of the palate was noted, and also the length, breadth and circumference of the head, and mental age, as determined by the YerkesBridges Point Scale Test.
The casts were made by first taking an impression of the upper teeth and hard palate upon dentists' modelling compound, a hard substance which when placed in hot water softens into a gum. The softened compound was carefully smoothed out onto a small tray which fitted into the mouth so as to include all of the teeth. An impression of the teeth and palate was made upon the modelling compound when the tray was pressed firmly against the roof of the mouth. The tray was then removed from the mouth, and a thin paste of dental plaster was poured into the impression and allowed to harden, after which the plaster cast was easily separated from the modelling compound when placed in hot water.
* Although the number of normal subjects examined is quite small, the results are identical with those of Channing and Wissler, in that the palate in abnormal individuals tends to be higher than in the normal. The writer feels justified, therefore, in the attempt to show that this increased height in abnormal individuals is not diagnostic of mental defect, but depends, rather, upon the shape and size of the head.
The instrument used to measure the casts was especially made by the mechanician at the University of Chicago, and consisted of a hard rubber horizontal bar, calibrated at one end, in which was set a screw which turned at each end. Attached to the horizontal bar was a calibrated vertical shaft, to which an adjustable rod was fixed in such a way that the measures of the length and
height of the palate were easily read off from the scale attached to the shaft. By means of inside calipers, the width of the cast at the two places desired (distance between the canines and between the first molars) was easily measured along the horizontal shaft. (See Fig. 1.)