HEREDITY IN MENTAL AND NERVOUS DISEASE
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1035 HEREDITY IN MENTAL AND NERVOUS DISEASE. HEREDITY IN MENTAL AND NERVOUS DISEASE. THE LANCET. LONDON: SATURDAY, MAY 16, 1925. THE transmission from parent to offspring of s mental and physical characteristics has been accepted ( as a fact from the beginning of time, but this principle f cannot be applied to disease processes quite so simply. ( The complex living organism is made up of a number i of individual entities together composing the whole, 7 and in the consideration of the transmission of 1 qualities the questions at once arise: Does the innate characteristic of the individual persist unchanged and is it transmitted in its unchanged form, or can the characteristic be modified during the life of the i individual, and can this modified characteristic be transmitted ? The Mendelian laws showed that in comparatively simple organisms, with clearly recognis- able traits, the innate characteristic persisted and that the manner of its appearance in the progeny could be mathematically computed. The advent of Darwinism and the theory of sporadic variation further deflected attention from the second possibility, but opinion now shows a trend towards the neo-Lamarckian attitude which affirms that the acquired modification may, under suitable circumstances, be passed on. The Mendelian law is very hard to apply in the complex organism and more particularly in the field of disease. It is difficult, in the first place, to pick out the definite fundamental trait, the unit characteristic ; what appears unitary may, in fact, prove to be highly complex. Apart from a very limited group of abnormalities, such as haemophilia, albinism, and certain familial myopathies, very little in this line has actually been accomplished beyorid the establishment of a certain persistence of characteristic in a family tree. In medicine it has been the custom to introduce the heredity as an aetiological factor in disease, especially in cases where no other definite causative factor is known. The history of pathological research, however, offers many instances where the hereditary influence was once supposed to be the all-important agent, when further advances in knowledge have shown the disease to be one acquired in the life-time of the individual. In such cases, even where the disorder has been definitely proved to be due to an environmental cause, such as the invasion of micro-organisms, the exponents of the hereditary theory merely change their ground and speak of a " diathesis " or a "constitutional tendency." Prof. ABRAHAM MYERSON, in a work reviewed in our columns this week, emphasises this point in relation to tuberculosis. He says: " Up till Trudeau’s time, in fact right up to the discovery of the tubercle bacillus by Koch, the main factor in the causation of the disease was held to be heredity. There were plenty of families found in which tuberculosis occurred generation after generation,’ plenty of families found in which all or many of the brothers and sisters had the disease, the same kind of evidence we have to-day for the ’inheritance of insanity.’ ... With the discovery of the infecting organism as a cause of tuberculosis heredity received a knock-out punch; in fact, everyone now loudly proclaims that there is no heredity in tuberculosis, but instead the meta- I physical predisposition’ is acclaimed, and still lingers to obfuscate intelligent thinking." I The real obstacle, as it appears to us, in the way of any advance in our knowledge of the hereditary transmission of disease lies, firstly, in the difficulty of finding a " unit character." There are few diseases which can be so regarded ; the majority are symptomatic groupings. Particularly does this apply to mental and nervous disorder, of whose ultimate nature we have at present little accurate knowledge and concerning which it is probable that future research will radically alter our conceptions. Secondly, we do not know how far a certain grouping of , symptoms may constitute a biological reaction to certain specific environmental circumstances. Because ) a certain symptom-complex appears in a national . or family grouping it does not necessarily follow that the cause lies within. There is a strong measure of , probability in the alternative explanation-viz., that E the mechanism of biological adaptation to the environ- ment is producing a similar series of reactions in a ( number of individuals exposed to the same conditions. 3Thirdly, we are remarkably ignorant of the laws 3governing degeneracy, atavism, or simple failure of 3 development. It is a matter of consideration whether 1 a number of the disease entities now recognised are - not phenomena of this order rather than disease t processes proper. B The progress of homo sapiens has been not biological 1 but sociological ; it has depended upon his control of i and ability to grow at the expense of his environment. v The development of man is not reckoned in terms of e biology but in terms of his capacity for using materials , -the Stone Age, the Bronze Age, the Age of Steam. e There has been steady progress in the manipulation of x the environmental factor, and it may be that the ;. hope of medical science lies in a further extension of e this principle. It is a comforting reflection that the ,t history of medicine shows a steady tendency to y eliminate the hereditary in favour of the environmental þf cause as the knowledge of morbid processes has become d more explicit. For it is still a question whether the s advance of the human race depends upon the adapt- Lt ability of man to his environment or upon his capacity 3. for adapting the environment to himself. le THE DYNAMICS OF THE CELL. IN man’s scientific struggle to bring under his direct control all the reactive phenomena exhibited by the animate and inanimate world, progress has been conditioned to a large extent by his power of analysing the concrete basis of his research into particles of ever increasingly minute dimensions, and of defining the laws governing their mutual interaction. Physics and chemistry are approaching each other on the common ground of atomic and molecular dynamics. Physio- logy, towards which medicine must unceasingly look for a rational interpretation of the problems which confront her, is on her part largely dependent, and ultimately entirely so, on the physico-chemical elucidation of the structure of matter. Without in the least wishing to disparage experimental work done on the whole animal and especially on man-work to , which physiology and medicine owe a great and lasting debt-we cannot refrain from emphasising the , tendency at present exhibited in physiology to make : use of the synthetic method of experimentation. , Such a method of study-namely, the study of the , functions of an organ isolated from the disturbing and : uncontrollable influences of the rest of the body- . enables a much more exact determination of the L reaction of the individual organ to changes in environ- ment to be made than would otherwise be possible.
Transcript of HEREDITY IN MENTAL AND NERVOUS DISEASE
1035
HEREDITY IN MENTAL AND NERVOUSDISEASE.
HEREDITY IN MENTAL AND NERVOUS DISEASE.
THE LANCET.
LONDON: SATURDAY, MAY 16, 1925.
THE transmission from parent to offspring of s
mental and physical characteristics has been accepted (
as a fact from the beginning of time, but this principle fcannot be applied to disease processes quite so simply. (
The complex living organism is made up of a number i
of individual entities together composing the whole, 7and in the consideration of the transmission of 1
qualities the questions at once arise: Does the innatecharacteristic of the individual persist unchanged andis it transmitted in its unchanged form, or can thecharacteristic be modified during the life of the iindividual, and can this modified characteristic betransmitted ? The Mendelian laws showed that incomparatively simple organisms, with clearly recognis-able traits, the innate characteristic persisted and thatthe manner of its appearance in the progeny could bemathematically computed. The advent of Darwinismand the theory of sporadic variation further deflectedattention from the second possibility, but opinion nowshows a trend towards the neo-Lamarckian attitudewhich affirms that the acquired modification may,under suitable circumstances, be passed on. TheMendelian law is very hard to apply in the complexorganism and more particularly in the field of disease.It is difficult, in the first place, to pick out the definitefundamental trait, the unit characteristic ; whatappears unitary may, in fact, prove to be highlycomplex. Apart from a very limited group ofabnormalities, such as haemophilia, albinism, andcertain familial myopathies, very little in this line hasactually been accomplished beyorid the establishmentof a certain persistence of characteristic in a family tree.
In medicine it has been the custom to introduce theheredity as an aetiological factor in disease, especiallyin cases where no other definite causative factor isknown. The history of pathological research, however,offers many instances where the hereditary influencewas once supposed to be the all-important agent, whenfurther advances in knowledge have shown the diseaseto be one acquired in the life-time of the individual.In such cases, even where the disorder has been
definitely proved to be due to an environmental cause,such as the invasion of micro-organisms, the exponentsof the hereditary theory merely change their groundand speak of a
" diathesis " or a "constitutionaltendency." Prof. ABRAHAM MYERSON, in a workreviewed in our columns this week, emphasises thispoint in relation to tuberculosis. He says:
" Up till Trudeau’s time, in fact right up to thediscovery of the tubercle bacillus by Koch, the mainfactor in the causation of the disease was held tobe heredity. There were plenty of families foundin which tuberculosis occurred generation aftergeneration,’ plenty of families found in which allor many of the brothers and sisters had the disease,the same kind of evidence we have to-day for the’inheritance of insanity.’ ... With the discovery ofthe infecting organism as a cause of tuberculosisheredity received a knock-out punch; in fact,everyone now loudly proclaims that there is noheredity in tuberculosis, but instead the meta- I
physical predisposition’ is acclaimed, and stilllingers to obfuscate intelligent thinking." I
The real obstacle, as it appears to us, in the wayof any advance in our knowledge of the hereditarytransmission of disease lies, firstly, in the difficultyof finding a " unit character." There are few diseaseswhich can be so regarded ; the majority are
symptomatic groupings. Particularly does this applyto mental and nervous disorder, of whose ultimatenature we have at present little accurate knowledgeand concerning which it is probable that futureresearch will radically alter our conceptions. Secondly,we do not know how far a certain grouping of
,
symptoms may constitute a biological reaction tocertain specific environmental circumstances. Because
) a certain symptom-complex appears in a national.
or family grouping it does not necessarily follow thatthe cause lies within. There is a strong measure of, probability in the alternative explanation-viz., thatE the mechanism of biological adaptation to the environ-ment is producing a similar series of reactions in a
( number of individuals exposed to the same conditions.3Thirdly, we are remarkably ignorant of the laws3governing degeneracy, atavism, or simple failure of3 development. It is a matter of consideration whether1 a number of the disease entities now recognised are- not phenomena of this order rather than diseaset processes proper.B The progress of homo sapiens has been not biological1 but sociological ; it has depended upon his control ofi and ability to grow at the expense of his environment.v The development of man is not reckoned in terms ofe biology but in terms of his capacity for using materials, -the Stone Age, the Bronze Age, the Age of Steam.e There has been steady progress in the manipulation ofx the environmental factor, and it may be that the;. hope of medical science lies in a further extension ofe this principle. It is a comforting reflection that the,t history of medicine shows a steady tendency to
y eliminate the hereditary in favour of the environmentalþf cause as the knowledge of morbid processes has becomed more explicit. For it is still a question whether thes advance of the human race depends upon the adapt-Lt ability of man to his environment or upon his capacity3. for adapting the environment to himself.le
THE DYNAMICS OF THE CELL.IN man’s scientific struggle to bring under his direct
control all the reactive phenomena exhibited by theanimate and inanimate world, progress has beenconditioned to a large extent by his power of analysingthe concrete basis of his research into particles of everincreasingly minute dimensions, and of defining thelaws governing their mutual interaction. Physics andchemistry are approaching each other on the commonground of atomic and molecular dynamics. Physio-logy, towards which medicine must unceasingly lookfor a rational interpretation of the problems whichconfront her, is on her part largely dependent, andultimately entirely so, on the physico-chemicalelucidation of the structure of matter. Without in theleast wishing to disparage experimental work done onthe whole animal and especially on man-work to
, which physiology and medicine owe a great and
lasting debt-we cannot refrain from emphasising the, tendency at present exhibited in physiology to make: use of the synthetic method of experimentation., Such a method of study-namely, the study of the
,
functions of an organ isolated from the disturbing and: uncontrollable influences of the rest of the body-. enables a much more exact determination of theL reaction of the individual organ to changes in environ-ment to be made than would otherwise be possible.
