cells, especially those in the motor area of the cortex in both cerebral hemispheres, present the so-called axonal alteration: the cell body is somewhat swollen; the stainable substance, especially in the central part of the cell, is converted into a diffusely staining, structureless, or into a finely powdered, mass; the nucleus is pushed toward the periphery of the cell and may be slightly flattened or distorted. Marchi preparations reveal corresponding degeneration of fiber tracts, particularly those connected with the motor cortical areas.

The nature of central neuritis is not understood, and but little is known of its etiology. Most cases that have been reported occurred in asylum practice either as terminal episodes in some chronic psychoses or in connection with acute mental confusion. It affects both sexes, chiefly in the fifth and sixth decades of life or thereabouts. In most of the cases no exciting cause is assigned; in a considerable number the trouble is said to have followed an attack of influenza, and in three cases it followed slight surgical operations done under general anesthesia.

Singer and Pollock found the lesions of central neuritis in a series of twelve cases of pellagra dying during the acute or subsiding stages of the pellagrous attack. "Seven of them died at a short interval after the skin lesions had subsided, with clinical symptoms of central neuritis. In the other five there were no symptoms, such as evidence of pyramidal tract lesion (Babinski reflex, jactatoid spasms, etc.),

1 Singer and Pollock. The Histopathology of the Nervous System in Pellagra. Archives of Internal Medicine, June, 1913.

to suggest central neuritis, although diarrhoea with rapid and progressive emaciation and weakness were almost always present." This, of course, suggests the possibility of an essential connection between central neuritis and pellagra which had been previously overlooked.

The mental symptoms, given in the order of their frequency, are: depression with anxiety or sudden apprehensiveness; restlessness and agitation; perplexity, confusion; hypochondriacal or persecutory delusions, often of an extremely absurd character; hallucinations. Refusal of food has occurred in more than half of the cases, and suicidal tendency is almost as common.

Among the physical symptoms the most striking are: stumbling, falling, unsteady gait; peculiar seizures, faintness, violent shaking, rigidity; muscular twitchings, irregular jerky movements, jactations; maladjustment in all movements; the knee-jerks are most frequently exaggerated, but in some cases they are diminished or even absent; the speech is apt to become very indistinct; toward the last, dysphagia; in some cases there is little or no reaction to pin-pricks. The general constitutional disturbance is grave: there is usually emaciation which may be extreme; diarrhoea has been observed in nearly three-fourths of the cases; a slight, irregular febrile reaction appears, the patient becomes exhausted, falls into stupor, and dies; in some cases death follows a sudden turn for the worse or actual collapse.

CHAPTER XXI.

MISCELLANEOUS GROUPS (Concluded).

SENILE DEMENTIA.

SENILE dementia may be defined as a peculiar state of intellectual enfeeblement, with or without delusions, resulting from cerebral lesions determined by senility.

1

Age is here, therefore, the great etiological factor; it is, however, not the sole factor. Many individuals attain extreme old age without presenting any appreciable intellectual disorders; others, on the contrary, have scarcely passed over the threshold of senility when they are already veritable dements.1 The effects of age are the more powerful and the more precocious the more marked the predisposition. Heredity, the intoxications (alcoholism), overwork, violent and painful emotions, traumatisms, etc., are also frequently given as causes.

Statistics furnish a rather small proportion of congenitally predisposed persons among senile dements, but this is perhaps partly due to the fact that it is frequently impossible to obtain reliable family histories in such cases.

Senile dementia is rare before the age of sixty

1 Russell. Senility and Senile Dementia. Amer. Journ. of Insanity, 1902.

years. Alcoholism sometimes brings about an analogous state of intellectual enfeeblement, appearing towards fifty or fifty-five years, which has been designated by the term sænium præcox.1 Such cases are exceptional if we exclude ordinary alcoholic dementia. The onset sometimes follows some strong emotional shock, financial troubles, or a somatic affection. Almost always it is insidious, marked simply by a change of disposition and slight disorders of memory. When fully established the dementia presents the following fundamental elements:

(a) Impairment of attention and sluggishness of association of ideas, readily demonstrable by psychometry, as has been shown by the experiments of Rauschburg and Balint.2 (These authors performed their experiments upon cases of simple senile dementia without delusions.) A curious fact observed in these experiments is that associations of ideas were

1 Cases essentially of premature senility have been described under the name of Alzheimer's disease. See Alzheimer. Ueber eigenartige krankheitsfälle des späteren Alters. Zeitschr. f. d. gesamte Neurol. u. Psychiatrie, Vol. IV, p. 365. Perusini. Ueber klinisch und histologisch eigenartige psychische Erkrankungen des späteren Lebensalters. Nissl's Arbeiten, Vol. II, p. 297.- S. C. Fuller. A Study of the Miliary Plaques Found in Brains of the Aged. Amer. Journ. of Ins., Oct., 1911.-S. C. Fuller. Alzheimer's Disease (Senium Præcox): The Report of a Case and Review of all Published Cases. Journ. of Nerv. and Ment. Dis., Vol. XXXIX, 1912. S. C. Fuller and H. I. Klopp. Further Observations on Alzheimer's Disease. Amer. Journ. of Ins., July, 1912.-W. J. Tiffany. The Occurrence of Miliary Plaques in Senile Brains. Amer. Journ. of Ins., Jan., 1914.

2 Ueber qualitative und quantitative, etc. Allgem. Zeitsch. für Psychiat., 1900.