On Growing New Neurons: Are Early Intervention Programs Effective

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On Growing

New

Neurons:

Are

Early

Intervention

Programs

Effective

Peggy C. Ferry, MD

From the Departments of Pediatrics and Neurology, University of

Arizona Health Sciences Center, Tucson

In recent years, there has been an exponential

proliferation of developmental stimulation pro-grams for environmentally deprived and neurologi-cally handicapped children.’ Premature infants in neonatal intensive care units are being cuddled, patted, stroked with vibrators, and rocked in water beds and motorized hammocks. They are exposed

to flashing lights, dangling birds and toys, and piped-in heartbeat sounds and music (“This Old Man”). Infants and preschoolers with neurologic disorders roll on beach balls in special “infant class-rooms,” on “therapeutic playgrounds,” and in “cre-ative play centers.” We have home-based, parent-oriented programs; home-based child-oriented

pro-grams; center-based, child-oriented programs; and, logically, center-based, parent/child-oriented ones. Older children with learning disabilities practice walking on balance beams to improve their gross motor skills and leaning abilities. The age of chil-then at entry, the nature of their handicaps, the

type and duration of intervention, the materials

used, and the qualifications of teachers and thera-pists all vary in a flood of new programs. “Infant

stim” and developmental therapy programs now represent a major industry in our country, employ-ing thousands of personnel (infant therapists, child

development specialists, movement therapists, physical and occupational therapists, early child educators, parent trainers, home teachers, and aides).

Without intending to promise normal brain de-velopment, personnel in many of these programs convey to parents the message that stimulation and

intervention will, in effect, grow new brain cells.

Sensory integration therapy, for example,

report-Received for publication Aug 4 1980; accepted Aug 12, 1980. Reprint requests to (P.C.F.) Department of Pediatrics, Univer-sity of Arizona Health Sciences, Center, Tucson, AZ 85724.

American Academy of Pediatrics.

edly “enhances the organization of brain mecha-nisms and neural integration.”2 Vestibular impair-ment is treated by providing “a bombardment of stimulation through the many different vestibular receptors activating synapses and increasing the number of impulses converging on neurons.”

A recent editorial in a leading child development

journal suggests that mothers should be advised to select mobiles and hand puppets for their infants, and should use “movement therapy and cerebellar stimulation in their daily activities with their ba-bies.”

As a pediatric neurologist, I am being asked, with increasing frequency, about the value of early inter-vention programs for neurologically impaired chil-dren. Questions come from referring physicians, parents, teachers, house staff, and medical students (but rarely from physical or occupational thera-pists). The working mother of a profoundly re-tarded, bedridden 2-year-old boy asked me recently, “Should I continue his stimulation therapy next year? I’ve been taking him to the Center faithfully, and the therapists have been coming to our home regularly to work with him, but it doesn’t seem to have made any difference. I’m wffling to do it if it’s

worthwhile, but we can’t afford to continue if it’s not.” Having seen this boy’s computed tomographic head scan, showing massive cortical atrophy and

cystic necrosis of both hemispheres secondary to

neonatal meningitis, I had reason to doubt the value of any intervention programs. Yet, if there was any potential value, I did not want to recommend stop-ping therapy.

On the other hand, one of my neonatology col-leagues told me recently of two severely hypotonic infants, one of whom lived in a rural area without

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SPECIAL ARTICLES 39 to go home. The parents continued this therapy

after discharge, and the child attended an infant stimulation program regularly. At 12 months of age, the second infant was performing three to four months ahead of the first in gross and fine motor

skills, personal-social areas, and language develop-ment. Did the therapy account for the difference in outcome, or could these differences have been the

result of basic differences in neural organization? Early identification and treatment is a widely accepted theme in many pediatric disorders, nota-bly hypothyroidism, phenylketonuria, hearing loss, and strabismus leading to amblyopia. Disuse atro-phy is known to occur after even brief periods of immobilization or paralysis. It is commonly ac-cepted that blind children have highly developed senses of hearing, touch, and smell and that sensory deprivation somehow leads to compensatory devel-opment of other neural pathways. Experimental evidence for the value of early intervention pro-grams in other developmental neurologic disorders

is less convincing. A recent article on early inter-vention programs for infants with Down syndrome showed no statistically significant differences in mental development between experimental and control groups.4 Conversely, another study showed that low birth-weight infants (without neurologic problems) treated with multimodel sensory

enrich-ment in the neonatal intensive care unit had sig-nificantly higher developmental scores at 7 months of age as compared to a control group.5

In spite of these two recent controlled and pro-spective studies, the field is hampered by enormous

methodologic problems. Many studies enroll a small

number of subjects, do not use a matched control group, evaluate only one or two aspects of devel-opment, use poorly standardized measures of out-come, and do not include sufficient longitudinal follow-up. A number of studies specifically exclude infants with known neurologic insults from the

study population. Confounding variables such as parental IQ, emotional health, and financial status

may not be analyzed.

The impetus for many of these studies came from the efforts of the Wa on Poverty and Project Head Start in the 1960s to “close the gap” in environmen-tally deprived children. Studies have shown, how-ever, that the graduates of Project Head Start showed increased social competence but a lack of measurable superiority in grade school

achieve-ment.6 Bronfenbrenner,7 in an address to the 1974 convention of the American Psychological Associ-ation, said, “Although there were some modest achievements, by and large the results were disap-pointing. The effects were at best short-lived and small in magnitude, with substantial overlap in the

distributions for experimental and control groups. In short, my optimism about the plasticity of the

developing organism and its responsiveness to en-vironmental change turned out to be ill-founded.”

Conversely, clinical observations and numerous animal experiments indicate that visual deprivation may produce irreversible anatomic conse-quences in the developing brain, including altered

retinal ganglion cells, transneuronal degeneration, smaller and less dense occipital neurons, deformed dendritic spines, and altered columnar organization of the cortex. Monocular visual deprivation in kit-tens leads to profound effects on the functional capabilities of neurons in the occipital cortex. How-ever, substantial recovery is possible even after prolonged monocular deprivation; evidence sug-gests that afferent optic nerve fibers “compete” for synaptic space on intact cortical neurons.8

Morphologic data from studies on sound-de-prived mice show that brain stem auditory neurons do not fully develop without adequate stimulation.9 Sound deprivation leads to diminished auditory

sensitivity and depleted cell groups in the auditory pathway.

Prenatal, unilateral, neurosurgical ablation of prefrontal cortex in rhesus monkeys stimulates neu-rons in the intact hemisphere to send projections to

the damaged side, providing direct evidence for neuronal rearrangement in the primate

telen-cephalon.’#{176} Sectioning of the pyramidal tract in infant hamsters produces massive regrowth of

sev-ered axons via a new pathway, indicating that axons in the mammalian nervous system damaged early in life may regenerate in a functionally useful way.” Experiments on salamanders have shown that a transplanted limb can be reinnervated from the newly grafted area of the spinal cord.’2

Rats raised in “enriched environments” (larger cages, increased numbers of “toys”) have measur-able differences in acetyicholine concentrations, in-creased thickness of the cerebral cortex, and in-creased branching of dendrites.’3 These changes,

noted mainly in the occipital cortex, were noted

even after two hours of exposure per day in the enriched environment. In these “super-rats” with more neural connections, an assumption has been that this environmental enrichment must somehow be beneficial. In some experimental tests, the

dam-aged, enriched rats responded as well as normal rats without brain lesions; in others, however, no im-provement was noted after exposure to the enriched

environment.

Infants and young children, particularly those with neurologic disorders, are not salamanders, hamsters, rats, or rhesus monkeys. Do the same principles apply? We know that shape, density, and

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position of various types of neurons is a highly complicated, genetically controlled, embryonic pro-cess of differentiation.’2 Many neurons show

che-mospecificity. The more complex neurologic struc-tures probably have less plasticity than those with

less sophisticated morphology. Collateral sprouting and selective reinnervation of nerve fibers has been noted in cats with spinal cord lesions; does the same process occur in infants? With the current state of knowledge, the answer is unknown. As noted by

Bross et al,’4 “Whether selective neural intercon-nections are indeed modifiable biochemical phe-nomena remains to be determined.”

Are functional connections in the nervous system strengthened by use? Much evidence exists to the contrary.’5 Functional improvement after cerebral lesions might also occur from reorganization of den-dritic connections of neurons in undamaged areas or from recovery of an incompletely damaged area.

Is there any possible hazard to early intervention or stimulation programs for handicapped children?

Older patients in intensive care units have been noted to develop psychiatric symptoms after being bombarded with sensory stimuli from monitoring devices. This “ICU syndrome” is best treated by reduction of lights and noise, and avoidance of the

sensory overload.’6 Could not the same be said for some of our low birth-weight infants in neonatal intensive care units? Rather than being stimulated by the “disco” environment, perhaps they are better left alone, as most of us would prefer to be if we were recovering from an intracranial hemorrhage, respiratory distress syndrome, or asphyxia. In older children, would the child with cerebral palsy be just as well-off (assuming a good home situation) spend-ing quiet time with a loving mother, with whom he is allowed to progress at his own rate? Does the time involved in therapy sometimes take away from activities with other children in the family, from the chance for the parents to spend time alone together, or from the mother’s growth in personal and career activities? Are parents really the best “therapists” for their children, or, in some cases,

should they be parents and not teachers? Does the time commitment really justify the end result? Do

these programs really keep parents from “shopping” for other forms of therapy?

Parents may suffer adverse effects from interven-tion programs. I have seen “rebound depression”

occur in parents of 4- to 5-year-old children who have been enrolled in intervention programs for several yeas. As the children become larger and more difficult to care for, and their neurologic status has not improved, parents are confronted with the growing realization that the child will be perma-nently and severely handicapped. Inadvertently, staff members in intervention programs may

sub-sidize the false hope that improvement will occur, thus delaying the parents’ emotional adaptation to the problem.

These same staff members seem unaware, in

many cases, of the permanent nature of brain dam-age in handicapped children. One therapist recently told me that a 2-year-old child with a large poren-cephalic cyst of the left cerebral hemisphere had

not received enough stimulation and therapy as an infant-hence the reason for his residual right hemiparesis.

Denhoff,’7 in response to a request by the Amer-ican Academy of Pediatrics’ Committee on Children

with Handicaps, has prepared an excellent review of the “state of the at” of these programs. As a

pediatrician who has worked with handicapped children for many years, he brings firsthand expe-rience and accumulated wisdom to a confusing and rapidly changing field. He stresses the important role of the pediatrician in helping parents arrive at a realistic appraisal of the child’s progress, a very difficult task when parents are burdened by the “syndrome of chronic sorrow.”8 He concludes that the benefits of infant enrichment programs clearly outweigh the disadvantages. After reviewing the currently available experimental and clinical facts, I cannot yet share his conclusions. There is no valid scientific evidence that these programs do alter neurologic development in high-risk or neurologi-cally handicapped children. While improvement in personal-social skills is a worthy goal, I suggest that continuing pediatric management, combined with conventional physical therapy, can provide this

re-sult without the need for more intensive

interven-tion therapy.

As Dr Denhoff notes, however, further studies are crucial to solving the many unanswered ques-tions in this controversial field. It is time that all of us concerned with the well-being of handicapped children took a hard look at early intervention programs, particularly in their design, data, and results. We must ask, “Do the programs work? If so, how do they work, for whom do they work, and how can they work better?” Does “one size fit all,” or are certain programs better for certain children? Who should be enrolled? When? With what type of handicap? What type of therapy should be used? How often should it be given? Who should provide it? Should it be done at home, in a center, or both? When should it be stopped? What are the potential hazards or contraindications? We must discriminate in our evaluation and recommendations, rather than blindly accept the many unjustified assump-tions which are being promulgated by well-inten-tioned but uninformed and unrealistic persons.

Large-scale, systematic, and scientifically

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SPECIAL ARTICLES 41

needed; whether funding for them can be found in

these inflationay times remains to be seen. In the meantime, I suggest that one immediate, practical service that pediatricians, developmental specialists, and neurologists can perform is to

edu-cate parents and nonmedical professional personnel concerning normal and abnormal development in infants and children, including the effects and nat-ural history of prematurity, intraventricular

hem-orrhage, asphyxia, cerebral malformations, menin-gitis, and cerebral palsy. We should also improve our efforts to counsel parents in these same areas.

In 1966 this journal published a commentary on “Unproven Methods of Treatment,”9 which dis-cussed treatment programs for children suffering from congenital or acquired brain dysfunction. The

author pointed out that new treatments may offer

nothing.which cannot be achieved by other means, with publicity and wishful thinking being

responsi-ble for their apparent success. Fourteen years later, the statement is stifi applicable to this topic. Surely

it is time for us to plan rational therapeutic en-deavors for the handicapped children and families we serve, which may, or may not, include early intervention or stimulation programs.

ACKNOWLEDGMENT

The author wishes to thank John M. Freeman, MD,

Jan L. Culbertson, PhD, Yvonne Vaucher, MD, and Elsa

Sell, MD for their help in the preparation of this paper.

REFERENCES

1. Belier EK: Early intervention programs, in Osofsky JD (ed):

Handbook of Infant Development. New York, John Wiley & Sons, 1979, chap 27, pp 852-894

2. Ayres AJ: Sensory Integration and Learning Disorders.

Los Angeles, Western Psychological Services, 1972, pp 114-120

3. Soboloff HR: Developmental enrichment programs. Dev

Med Child Neurol 21:423, 1979

4. Piper MC, Pleas IB: Early intervention for infants with Down syndrome: A controlled clinical trial. Pediatrics 65: 463, 1980

5. Leib SA, Benfleid G, Guidubaldi J: Effects of early interven-tion and stimulation on the preterm infant. Pediatrics 66:83,

1980

6. Zigier E: Project Head Start: Success or failure? in Zigler E, Valentine J (eds): Project Head Start. New York, The Free Press, 1979 chap 23, p 495

7. Bronfenbrenner U, cited by Palmer FH: The effects of early childhood intervention, in Brown B (ed): Found: Long-Term Gains from Early Intervention. Boulder, CO, Westview Press, 1978, chap 1, p 14

3. Timney B. Mitchell DE: Behavioral recovery from visual deprivation: Comments on the critical period, in Freeman

RD. (ed): Developmental Neurobiology of Vision. NATO Advanced Study Institutes, Series A, Life Sciences. New York, Plenum Press, 1979, vol 27 p 149

9. Webster DB, Webster M: Effects of neonatal conductive hearing loss on brain stem auditory nuclei. Ann Otol Rhinol Laryngol 88:684, 1979

10. Goldman PS: Neuronal plasticity in primate telencephalon: Anomalous projections induced by prenatal removal of fron-ta.l cortex. Science 202:768, 1978

11. Grobecker DB, Pietsch TW: Regrowth of severed axons in the neonatal central nervous systems: Establishment of nor-mal connections. Science 205:1158, 1979

12. Szekely G: Order and plasticity in the nervous system.

Trends Neurol 2:245, 1979

13. Greenough WT: Enduring effects of differential experience and training, in Rosenzweig MR, Bennett EL (eds): Neural

Mechanisms of Learning and Memory. Cambridge, MA, MIT Press, 1976, chap 16, pp 255-278

14. Bross M, Harper D, Sicz G: Visual effects of auditory dep-rivation: Common intermodal and intramodai factors. Sci-ence 207:667, 1980

15. Sharpless 5K: Reorganization of function in the nervous system-Use and disuse. Annu Rev Physiol 26:357, 1964 16. Imboden JB, Urbaitis JC: Practical Psychiatry in Medicine.

New York, Appleton-Century-Crofts, 1978, p46

17. Denhoff E: Current status of infant stimulation or enrich-ment programs for children with developmental disabilities.

Pediatrics 67:32, 1981

18. Olshansky S: Chronic sorrow: Response to having a mentally defective child, in Counseling Parents of the Mentally Re-tarded. Springfield, IL, Charles C Thomas Publisher, 1970, chap 4

19. Masland RL: Unproven methods of treatment. Pediatrics

57:713, 1976

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1981;67;38

Pediatrics

Peggy C. Ferry