Preventable

cause of

Mental Retardation

Guide: Dr. Deepak Dwivedi Dr.Priyank Patel

Mental Retardation

Mental retardation is defined as subaverage general

intelligence, manifesting during early developmental period.

The child has diminished learning capacity and does

not adjust well socially.

Now the term mental retardation has been replaced by

Intellectual disability.

Intelligence quotient:

It is calculated according to the formula

Mental Age divided by chronological age, multiplied

by 100.

Diagnostic criteria for intellectual disability

A Significantly subaverage intellectual functioning: an IQ

score of 70 or below on an individually administered

IQ test(for infants, a clinical judgment of significantly

subaverage intellectual functioning)

B Concurrent deficits or impairments in present adaptive

functioning (i.e.,the person’s effectiveness in meeting

The standards expected for his or her age by his or her

cultural group) in at least two of the following areas:

communication, self-care, home living, social and

interpersonal skills, use of community resources,self-

direction, functional academic skills, work,leisure,

health, and safety.

C The onset is before age of 18 years.

Grading of intellectual disability:

Mild intellectual disability: IQ 50-55 to 70

Moderate intellectual disability IQ 35-40 to 50-55

Severe intellectual disability IQ 20-25 to 35-40

Profound intellectual disability IQ below 20-25

Intellectual disability, Severity unspecified, when there is

strong presumption of intellectual disability but the person’s

intelligence is untestable by standard tests.

Causes of Intellectual disabilityPrenatal factor:

Aminoacidopathies: Organic acidemia, Phenylketonuria,

hompcystinuria, histidinemia, organic aciduria

Carbohydrate disorder: Glycogen storage disorder, glucose transport defect, galactosemia

Chromosomal disorder: Down syndrome, fragile X syndrome, Klinefelter syndrome

Iodine deficiency

Neuroectodermal dysplasia: Tuberous sclerosis

Developmental defects: Microcephaly, craniostenosis,

porencephaly, cerebral migration defect

Maternal factor:

Use of teratogens in first triamaster of pregnancy

Intrauterine infection

Placental deficiency, toxemia of pregnancy, antepartum

hemorrage

Radiation during prenancy

Natal factor:

Birth injury

Hypoxic ischemic encephalopathy

Intracerebral hemorrhage

Post natal factor:

Infection of central nervous system

Head injury

Thrombosis of cerebral vessels

Post-vaccinal encephalopathies

Kernicterus, hypoglycemia

Hypoxia, hypothyroidism

Malnutrition , child abuse

autism

Development screening

Phatak’s Baroda screening test:

This is India’s best known development testing

system but meant to used by child psychologist rather

than physician.

Denver development screening test:

It has 4 domain i.e. gross motor, fine motor

adaptive, language and personal social behavior

Trivandrum development screening chart:

it is simplified adaptation of Baroda development

screening system.

applicable to children up to 2 year of age

useful as a mass screening test.

•Goodenough-Harris drawing test

•Clinical adaptive test and clinical linguistic and auditory

milestone scale (CAT/CLAMS)

Definitive test

Bayley scale for infant development II

it is the most commonly used scale.

usually takes 30-60 min to assess

Assesses language behavior, fine motor,gross motor,

and problem solving skill, provides mental

development index and psychomotor development

index

Wechsler intelligence scale for children IV:

The most commonly used psychological test for children

>3 year of age

Assesses verbal and performance skill

Provide full scale IQ and indices of verbal

comprehension perceptual reasoning workig memory

and processing speed

Other test like

Stanford-Binet intelligence scale 5th edition

Factors affecting Development along with preventble cause of intellectual disability

Prenatal factors:

•Genetic factors: Intelligence of parents has direct

correlation on the final IQ of the child.

There are several genetic causes for development

Delay and subsequent mental retardation.

(1)Neuro-Metabolic diseases:

There are few neuro metabolic disorder which if

diagnosed and treated timely can be prevent

developmental delay in child.

(a) Phenylketonuria:

This disorder is caused by deficiency of enzyme phenyl

alanine hydroxylase.

The affected infant is normal at birth.

Profound mental retardation develop gradually if the

infant remains untreated.

Vomiting may be an early symptom.

The infant are lighter in their complexion than unaffected

sibling.

Neurological symptom include seizure, spasticity, hyperreflexia,

and tremor.

Microcephaly ,

Prominent maxillae with widely spaced teeth.

Growth retardation

Diagnosis:Quantitative measurement of plasma phenylalanine

concentration.

Treatment: Should be treated with a phenyl restricted diet.

Formula low or free of phenyalanine ar e commercially available.

(b)Galactosemia:

Denotes elevated level of galactose in blood.

caused mainly due to deficiency of

(i) galactose-1-phosphate uridyl transferase

(ii)galactokinase

(iii) uridine diphosphate galactose-4-epimerase

Clinacal feature:

Jaundice

hepatomegaly

Vomiting

Hypoglycemia

Seizure

Lethargy, irritability

Poor weight gain

Hepatic failure

Splenomegaly

Mental retardation

Ascitis

Diagnosis:

The preliminary diagnosis is made by demonstrating a

reducing substance in several urine specimens collected while

the patient is milk or any other formula containing lactose.

For confirmation quantitative measurement can be done

Treatment:

Non lactose containing diet

Hypothyroidism

All inborn error of metabolism should be diagnosed at the earliest and should be treated.

Maternal factor:

(i)Maternal malnutrition:

deficiency of various micronutrient can

adversely affect development of fetus and later on can

have influence on infant development

(ii)Exposure to drug and toxin:

use of alcohol during pregnancy can affect

mental development of infant.

Fetal Alcohol syndrome

Occurs because of high level of alcohol ingestion during

pregnancy.

Clinical feature;

Prenatal onset and persistence of growth deficiency

facial abnormality including short palpebral fissure,

epicanthal fold, maxillary hypoplasia,

micrognathia, smooth philtrum, smooth upper lip

Cardiac defect primarily septal defect

Minor joint and limb abnormalities

Mental retardation

Treatment:

No specific therapy exists

Prevention:

By eliminating alcohol intake after conception.

Maternal smoking causes decreases in birth weight. Along

with this it also cause defect in brain, heart and face,

Use of cocaine and opioid during pregnancy can cause

serious problem in fetus.

Valproic acid can have severe defects in child

Maternal exposure to radiation also have deleterious effect

upon fetal developments

Maternal diseases and infection :

Pregnancy induced hypertension

Hypothyroidism

Feto-placental insufficiency due to any cause

Acquired infection e.g. toxoplasmosis,

Rubella, CMV, herpes, Chorio-amniotis

(iii)Maternal infection:

Among various infection one of the most imp. Is

TORCH infection

Toxoplasmosis:

caused by Toxoplasma gondii, an obligate

intracellular protozoan.

There is a wide variety of manifestation:

May lead to hydrops foetalis and perinatal death

Classical triad is

Chorioretinitis

Cerebral calcification

Hydrocephalus

Diagnosis:

diagnosis can be done by culture or serological tests

Treatment:

Pyrimethamine

Sulfadiazine

Cytomegalo virus infection

Congenital infection can manifest as

IUGR

Prematurity

Hepatosplenomagaly

Jaundice

blueberry muffin like rash

Thrombocytopenia

Microcephaly

intracranial calcification

Diagnosis:

definitive method of diagnosis is virus isolation or

demonstration of CMV DNA by PCR.

Treatment:

Ganciclovir, foscarnet, cidofovir

Neonatal Risk factor

Intrauterine growth restriction:

Adversely affect development

Prematurity:

Chances of developmental impairment

increases with prematurity. More the child is premature

more will be the risk. Mainly because of complications like

intracranial bleed, white matter injury, hypoxia, hyper-

bilirubinemia and hypoglycemia

Various metabolic derangement can affect child

development like

Hypoglycemia

Hypocalcemia

Hyperbilirubinemia

Hyperthermia

Perinatal asphyxia:

Studies have indicated that over 40%

of survivor of significant asphyxia suffer from

major neurocognitive disabilities.

Incidence can be decreased by Institutional delivery, proper

resuscitation, early stimulation therapy

Post natal factors :

Infant and child nutrition:

Early growth faltering (<24 month ) seems

to be more detrimental to childhood development.

Calorie deficeincy associated with multiple micronutrient

and vitamins like zinc, vitamin A, B12, D, E contribute to

developmental impairment.

Iron deficiency

Associated with delayed brain maturation, poorer

cognitive, motor and social emotional development

Iodine deficiency

it can lead to congenital hypothyroidism and

irreversible mental retardation, making it the most common

preventable cause of mental retardation.

Infectious disease

Diarrhoea, malaria, other parasitic infection and HIV

Environmental toxins

Like lead, arsenic, pesticide, mercury, and polycyclic aromatic

hydrocarbons

Exposure may be prenatally through maternal exposure or

postnatally through breast milk, food, water, house dust, soil

Acquired insult to brains:

traumatic or infectious insult like meningitis,

encephalitis, cerebral malaria and other factor like near

drowning, trauma particularly during early years of life can

have a permanent adverse effect on brain development.

Associated impairment

impairment particularly those involving sensory inputs

from the eyes or ears can have a significant impact on

attainment of milestone.`

Psychosocial factor

Parenting:

cognitive stimulation, caregiver’s sensitivity and affection

have important role in child development.

Higher level of maternal warmth and responsiveness are

associated with higher cognitive ability and reduced level of

behavioral problems in young children.

Poverty:

this is possibly the most common underlying

factor for impaired child development.

Lack of stimulation:

Social and emotional deprivation and lack of

adequate interaction and stimulation is an important cause

of developmental impairment.

Violence and abuse:

Domestic and community violence can have profound psychological effect on the child.

Maternal depression:it is negatively associated with child

development.

Institutionlization:Institutional care like orphanages during

early life increases the risk of poor growth, ill health, attachment disorder

Protective factor:

Breastfeeding:

have protective and promotive effect on child

development.

Maternal education:

has protective effect

Congenital Hypothyroidism

•It is the most common preventable cause of mental

retardation.

•Iodine deficiency is the most common cause of congenital

hypothyroidism.

Clinical feature:

Most infant with congenital hypothyroidism are

asymptomatic at birth due to transplacental passage of

maternal T4.

Despite having maternal thyroxine infant have low level

of serum T4 and elevated TSH.

Twice common in girls than boys

Birth weight and Height are normal but head size may be slightly increased.

Prolongation of physiologic jaundice may be the earliest sign.

Feeding difficulties especially sluggishness, lack of interest, somnolence and choking spell during nursing are often present.

Respiratory difficulty due to large tongue

Poor appetite, constipation

Umbilical hernia

Temperature is subnormal.

Large abdomen

Edema of the genital and extremities

Pulse is slow, heart murmur, cardiomegaly, pericardial effusion

Macrocytic anaemia

Congenital anomaly mostly cardiac

Hearing loss

Widely opened anterior and posterior fontenelle

Neck short thick

Hands are broad and fingers are short

Myxedema mainly in skin of eyelids, the back of the hands,

and external genitalia.

Development is delayed

Hypotonia

Lab diagnosis:

For Newborn Screening blood is obtained between 2 and

5 day of life by heel-prick.

Serum level of T4 or free T4 are low; serum level of T3 may be

normal and not helpful in diagnosis.

If the defect is primarily in thyroid level TSH are elevated.

Radiological:

• Retardation of osseous development can be seen.

• The distal femoral epiphysis, normally present at

birth, is often absent.

• the epiphysis often have multiple foci of ossification.

• Deformity of T12,L1, L2 is common.

Electrocardiography

may show low voltage P and T wave with diminished

Amplitude of QRS complex and suggest poor left ventricular

function.

Echocariography:Pericardial effusion may be seen.

EEG:often shows low voltage

MRI:normal

Treatment:

Levothyroxine given orally is treatment of choice.

the recommended initial starting dose is 10-

15ug/kg/day

Neonate with more severe hypothyroidism should be

started at the higher end of dosage range.

Thyroid function test should be done at recommended

interval usually monthly in first 6 month of age then at

2- 3 month interval.

Thyroid replacement should be stopped for one month at

the age of 3 yr in suspected transient hypothyroidism.

Treatment may be discontinued in the absence of persistent

Abnormality on investigation and normal level of thyroid

hormone.

Prognosis:

Early diagnosis and adequate treatment from the first

weeks of life result in normal linear growth and

intelligence.

Most severely affected children can have retarded

skeletal maturation and have reduced IQ and can have

other neurological consequences like hypotonia,

hypertonia, incoordination, short attention span and

speech problem

Prevention and control:

Iodine disorder are best prevented as treatment

is usually ineffective. Iodinated salt and iodized oil are

highly efficacious in preventing iodine deficiency.

The National Goiter Control Program of the Ministry

of Health in India began in 1962 with establishment of

iodination plant.

Prevention of Mental Retardation

Examples of primary program to prevent intellectual

disability include:

Increasing the public’s awareness of the adverse effect of

alcohol and other drugs of abuse on the fetus.

Preventing teen pregnancy and promoting early prenatal care

Preventing Traumatic injury: Encouraging the use of guards

and railing to prevent fall and other avoidable injuries in the

Home ; using appropriate seat restraints when driving and

wearing a safety helmet when biking ; teaching firearm safety

Preventing Poisoning: Teaching parents about locking up

medications and potential poison.

Implementing immunization programs to reduce the risk of

intellectual disability due to encephalitis, meningitis and

congenital infection.

Newborn hearing screening programs.