Tredgold expresses the opinion that "the insanity of the feebleminded and high grade imbeciles does not, on the whole, differ from that occurring in ordinary persons." In sixty-two cases under his observation he found the following forms:—Mania, thirty-two; melancholia, sixteen; alternating mania and melancholia, six; stupor, one; delusional insanity, one; and juvenile general paresis, six. He also speaks of epileptic insanity and terminal dementia in his cases.
Kraepelin[348] describes certain characteristics as applying very generally to the mental deficiency group which he prefers to speak of as "Oligophrenia." Sense perception is often interfered with by defective vision, opacities of the lens and cornea, errors of refraction, optic atrophy or deafness. The apprehension of external impressions may be prevented to a certain extent also by disturbances of attention. Only the sharper and stronger stimuli reach the patients as a rule and these impressions are retarded. Many occurrences escape their notice entirely and their sense perceptions are poor and scanty at best. Disturbances of attention are shown by the attitude, facial expression, carriage and conduct, so that they have an appearance of apathy and indifference when their real feelings are entirely different. An increased effort cannot be produced by an exertion of the will, nor can the fatigue which such attempts result in, be overcome. Repeated tests of various kinds show a marked decrease in the power of apprehension. In profound idiocy it is difficult to determine whether any impression can be made on the sense organs or not. When the patients react to a severe pin prick it is only after a considerable delay, apprehension and attention being equally impaired. Schlesinger found fifty-five per cent of his cases lacking in interest, thirty-five per cent were distractible and ten per cent showed an increased fatigability. An evidence of the lack of attention is the fact that the weakminded as a rule are not susceptible to hypnotism.
The apprehension of colors, form and dimensions is uncertain and difficult. The patients learn to distinguish colors very late usually. They can form no clear conception as to the outlines, surface or contents of objects. They have considerable difficulty in putting syllables and sentences together. They recognize the details but not the significance of pictures. In the elaboration of impressions they are unable to distinguish between the real and the accidental or nonessential. This gives rise to a confusion of ideas. Changes in size, color, shape, etc, always annoy them. Their lack of observation and discrimination explains the absence of timidity in the presence of strangers which characterizes normal children. There is also a defective apprehension of auditory impressions and they are unable to understand very familiar sounds. Ley showed that they were often unable to identify letters they heard pronounced. There is a marked inability to grasp the meaning of ordinary words. The sense of taste and smell is comparatively much less impaired. Very defective children object at once to quinine when it is placed on the tongue. Nevertheless, many do not notice unpleasant odors or even the taste of excreta, etc.,—things which are exceedingly offensive to normal individuals,—and are entirely indifferent as to the quality of their food. Sensory disturbances of the skin are not very marked. In a series of esthesiometric tests, however, Ley obtained unsatisfactory "automatic" responses in eighteen cases, meaningless answers in forty-eight, and intelligent responses in eleven of 127 mental defectives examined. The application of the sense of touch in recognizing articles is acquired with difficulty. Pain sensations are somewhat diminished also and some defectives are apparently insensible to blows, etc. That the sense of position and location is not well developed is often shown by coarse, awkward movements. The sense of weight and motion is lacking. Demoor found that the feebleminded usually pointed out the larger article as being the heavier even when lighter in weight. Claparede found this characteristic present in one per cent of ninety-seven pupils rejected as a result of mental tests, in eight per cent of the mildly weakminded, and in sixty-five per cent of the markedly defective cases. Memory is always involved. Superficial impressions are easily lost. Johnson subjected seventy-two defective children to retention tests. Seventy could correctly repeat only three numbers; sixty-six only four; fifty-one only five; twenty-seven only six; fourteen only seven, and four only eight. Ranchburg's tests showed them to be very susceptible to suggestion. Some defectives, on the other hand, have a peculiar faculty for remembering dates, numbers, performing feats of arithmetic, etc. The memory defect is usually shown more especially by the inability to take advantage of the experience of the past. The patients learn with difficulty, read little and forget what they are taught. The events of life leave few traces and make only a superficial impression on them. The intellectual horizon for this reason is very limited. Their thoughts are confined largely to the matter of clothing, food, etc.
The fundamental obstacle in the mental progress of the defectives is the inadequate elaboration of general impressions and conceptions. There is an absence of any understanding of the importance of time, events, numbers, etc. They often have no idea whatever as to the significance of money. Dates mean nothing usually and they are often unable to determine the time of day. The train of thought as shown by tests made by Buccola is delayed. Their poverty of thought is shown by the fact that defective children can think of only about one-fourth as many words during a given time as suggest themselves to the normal child—a test suggested by Binet. Tests reported by Sommer, Nathan, Binet and others show a marked delay in association time and an impoverished mental capacity. They frequently repeat the test word or give entirely meaningless replies. Associations do not become fixed on repeated tests as they do with normal individuals (Wreschner). It is not easy for them to repeat numbers, the months of the year or days of the week backwards. They cannot supply omitted words or syllables in sentences (Ebbinghaus test). It is hard for them to assemble picture puzzles or pieces of cards. Revesz found that it was more difficult for them to learn to divide than to subtract or add. Multiplication he found to be most easily acquired. They did not do well in tests requiring any reason or judgment. They are entirely incapable of defining or explaining abstract conceptions of any kind. They cannot explain the meaning of fables and have no appreciation of irony. Nor can they correct the most obvious faults in test sentences. They have no insight into their own condition and no grasp on either past or present events. Their capacity for efficient occupation and employment is much diminished. Their ability to acquire an education is also limited. Of 286 cases examined in school Schlesinger found only fifteen per cent to be industrious in their habits. Nine per cent failed in writing, eighteen in reading and twenty-four per cent in arithmetic tests.
The emotional life is also much impoverished and unstable. There is no sense of shame and no feeling of family pride or patriotism. There is often a tendency to commit criminal acts. As a rule the mood is indifferent and apathetic—in strange surroundings they are sometimes timid and anxious. Some feel ashamed of their speech defects and awkwardness. Others show a childish cheerfulness, or satisfaction and self-confidence. There is a tendency to uncontrollable laughter, attacks of anxiety, angry excitement, or childish despair with hysterical manifestations which disappear quickly. Usually the patients are inoffensive, manageable and well behaved, but easily susceptible to bad influences. Often they are queer, whimsical, capricious, obstinate and childish. Henneberg, who examined a large series of cases, described 33.8 per cent as anxious, timid, sensitive and inclined to weep; 15.7 per cent as apathetic, dreamy, sluggish and seclusive; 12.6 per cent as quiet, serious, good-natured, sociable and pleasant; 18.7 as active, cheerful, shallow, playful and talkative; and nineteen per cent as rude, malicious, obstinate, irritable and bad-tempered. The sexual life is sometimes undeveloped or may show actual perversions. Bonhöffer found six idiots and fifty-three feebleminded persons in an examination of 190 prostitutes. The volitional expressions of the defective are very largely impulsive. They act without reflection or regard to consequences and are easily induced to do improper acts. The inhibition of will is shown by the defective control of ordinary movements in responding to commands. They are always slow in learning to walk. The childish inability to perform finer and more precise movements does not disappear later as it does in the course of normal development. This is shown in their gait, awkward movements, etc. Kraepelin interprets the tendency to bedwetting as an evidence of volitional disturbance, also the stereotyped, rhythmical movements of the idiot. Laser found that forty per cent of his cases had the habit of biting the finger nails.
Dependent upon the inhibition of volitional impulses, two clinical groups of the feebleminded have been described by Kraepelin,—the excitable and the apathetic or dull. The excited forms are much more common. Schlesinger, however, found thirty-one per cent of his cases of the apathetic variety; twenty-nine per cent were excitable; twenty-eight per cent had simple mental defects, and the remainder showed antisocial tendencies. In the apathetic or dull form there is a marked disturbance of the attention; the patient takes no interest in his surroundings, appears sluggish, awkward, emotionally dull, and devoid of any voluntary impulse, often doing only what he is urged to do. They are usually good-natured, contented, and do simple work under direction, in a slow and mechanical way. The lighter grades are of a dull, weak-willed, readily influenced type. They are timid, unconcerned and agreeable. The excitable variety, on the other hand, show a purposeless, mercurial variability. Their attention is easily distracted from one thing to another. They cannot sit still, are restless and constantly on the go. Occasionally they are violent.
The defective control of motor impulses by the will is also shown in defectives by the disturbance of speech and writing. Crailsheimer found speech disturbances in 36.3 per cent of his cases, Schlesinger in thirty per cent, and Leubuscher in fifty per cent. They can often hear although mute, sometimes recovering their speech during an attack of excitement. Ley reported stammering in twelve per cent of his cases and stuttering in thirteen per cent. Agrammatism and akataphasia sometimes occur. Word-blindness is also referred to as a symptom and various disturbances of reading and writing have been observed.
According to Kraepelin, the important developmental landmarks in the life of the young are the acquisition of speech (one year), the beginning of the school life (six years), the appearance (fourteen years) and the completion (eighteen years) of sexual development. The first and second periods represent the relative levels of low and high grade idiocy, the third imbecility and the fourth feeblemindedness. This classification is somewhat similar to that of Weygandt. The education ordinarily acquired by the higher grade of the feebleminded is somewhat limited. They may even excel in certain occasional lines of work, for example, in music, art, etc. They are usually poor in mathematics and lack interest and application as a rule. Difficult apprehension and mental fatigability are to be expected. They have to go over things repeatedly, as their memory is not good. Their education is often ample in some directions and very lacking in others. Their judgment is onesided, their viewpoint narrow and their worldly knowledge childish. What they acquire at school is soon forgotten. They take no interest in religion, politics or current events of importance, and very impractical ideas are expressed on all questions. The emotional manifestations vary. Some are agreeable, cheerful, tractable; others timid, tenderhearted, sensitive, slightly emotional or anxious. They are more likely to be obstinate, stubborn, unruly, rude, irritable, unsociable and violent-tempered. Some have periods of active excitement and become threatening, abusive and violent. Occasionally suicidal attempts are made, although they are usually not genuine. Some are addicted to sexual excesses, lying or swindling. Sexual perversions also occur in some cases. They are usually incapable of any continuous occupation and drift from one thing to another. As a rule they have little conception of the value of money and spend it recklessly. They are very susceptible to alcoholism and often commit petty crimes. Occasionally hysterical manifestations—syncopes, seizures, etc.—appear. Clouded and confused states have been observed. Frequently impulsive tendencies are noted. In some instances psychopathic traits are very striking. Excitable, unstable, impulsive, quarrelsome and antisocial types appear as well as liars and swindlers. Periodical excitements and depressions suggest manic-depressive forms.
Considerable confusion has been occasioned by the relation thought by some to exist between mental deficiency and dementia praecox. Kraepelin[349] has spoken of an engrafted hebephrenia, as shown by the following quotation from his eighth edition:—"I made the suggestion a long time ago that certain, not very frequent, forms of idiocy with well developed mannerisms and stereotypies were an early expression of dementia praecox." He is of the opinion that "the affected manners of certain idiots, as well as the associated stereotypies of attitude and movement in addition to the negativistic impulses and the permanent obstinate inaccessibility to all attempts at approach, show no relation whatever to ordinary childish peculiarities and belong on the contrary to the well-known picture of dementia praecox." He interprets the "demenza precocissima" of Sante de Sanctis and the "dementia infantilis" of Heller as belonging to dementia praecox rather than the mental deficiency group. He further makes the suggestion that "weakmindedness existing from youth without focal symptoms, and later leading to deterioration, is as a rule to be looked upon as pfropfhebephrenia, if epilepsy and cerebral syphilis can be excluded, the former by the absence of seizures, the latter by the results of the Wassermann reaction." Engrafted hebephrenia or "pfropfhebephrenia" has been studied by various observers. After an analysis of ten cases Wasner reached the conclusion that feeblemindedness predisposes to dementia praecox. Weygandt and various other writers are not in accord with Kraepelin on this subject. It is, however, generally conceded that the occurrence of manic-depressive and other affective psychoses in mental defectives is not at all infrequent.
As special types Kraepelin described microcephalic varieties, the tuberous sclerosis of Hartdegen and Bourneville (1880), vascular and other cerebral defects, infantilismus, dysadenoid and other endocrine conditions, Mongolian idiocy, hydrocephalus, encephalitic forms, etc. Alzheimer, Hammarberg, and Bourneville have made pathological classifications of the mental deficiencies.