Developmental Neuropsychology

Prepared by:Cicilia Evi GradDiplSc., M. Psi

Introduction

• The process of development does not always run smoothly it is important to understand the disorders of development for treatment

• Development of neuronal connections remains unsolved believed that both genetically determined intrinsic factors and environmentally generated extrinsic factors contribute to the connectivity of the mature NS

Intrinsic Factors

• Chemospecificity hypothesis by Roger Sperry (1968, 1971):– Neurons become chemically differentiated at early

stage of their development before environmental input is available

– Have chemical labels enable the neurons to recognize their targets regeneration of neural tissue

Extrinsic Factors

• Mostly in later stages of development when neuronal connections depend on which connections receive the most environmental stimulation

• Plasticity NS’s capacity to undergo adaptive modification in response to environmental or genetically based disruptions of normal development ex: how brain reorganize itself after local injury or other external influences

Known Causes of Dev Abnormality• Inherited Disorders – Autosomal dominant transmission transmission via

chromosomes other than sex chromosomes requires only one parent gene

– Autosomal recessive transmission requires two genes, one from each parent ex: PKU that causing mental retardation (intellectual disability)

– Sex-linked transmission any genetic disorders affecting one sex selectively, presumably due to a gene on the sex chromosome

– Polygenic inheritance interaction of several genes and also with environmental factors

Contd.

• Chromosomal Disorders include a group of defects of the chromosomes as identified by abnormalities of their configuration (karyotype) due to either environmental or genetic factors – Trisomy extra chromosomes of three trisomy 21 or

Down Syndrome – Translocation mismatching of chromosomes pairs or

portions of a chromosome– Partial or complete deletion of a chromosome ex:

Turner’s syndrome (missing X chromosome) impairments in perception of form and space

Contd.

• Structural Abnormalities due to disruptions of development cause death or severe impairments:– Anencephaly lack of brain development – Microcephaly very reduced brain development

• Prematurity and Low Birth Weight – Prematurity either a birth weight of less than

2,500 g or birth before 37 weeks of gestation (WHO, 1961)

Contd.

• Infection – Prenatal rubella, which is associated with

microcephaly, meningoencephalitis and mental retardation

– HIV cognitive impairments on children (not yet developed AIDS)

– Hypothesis also link to development of intelligence, LD and serious psychopathology, incld. schizophrenia still weak

Contd.

• Toxin-Related Damage – Fetal Alcohol Syndrome from alcoholic mothers characterized by facial malformations, intrauterine growth retardation and neurobehavioral dysfunction (include increased period with eyes open, body tremors, and decreased vigorous body activity(

– Lead poisoning associated with hyperactivity and poor performance in intelligence tests

Contd.

• Nutritional Disorders – Kwashiorkor protein-deficient diet – Marasmus energy-deficient diet – Malnutritional milieu when nutritional deficiency is

being accompanied by other environmental and health-related problems early sign: low birth weight influence cognitive abilities

– Nutritional deficiencies in adulthood specific cognitive impairments: Wernicke-Korsakoff syndrome

Contd.

• Anoxic Episodes a period of oxygen deprivation, which can result in hypoxic- ischemic encephalopathy – Hypothesis undiagnosed anoxia in early life may cause

subclinical anoxic pathology neuropsychological impairments, incld LD received little empirical support

• Traumatic Brain Injury Infants and children are vulnerable to the effects of traumatic brain injury and neurological diseases such as neoplasms and stroke

Dev Disorders of Unknown Cause

• Learning Disorders • Attention Deficit Disorder• Autism

Learning Disorders

• An impairment in a specific domain of cognitive, such as: reading, math, or spatial processing not attributable to general intelligence, lack of opportunity to learn, inadequate home environment, inadequate motivation or a handicapping condition

• Presumably due to CNS dysfunction but often unknown

• Dyslexia, dyscalculia and non-verbal LD

LD (2)

• Dyslexia specific disorder of reading– Surface dyslexia (phonological reading) inability to form

word-sound correspondences without subjecting the word to phonological analysis can’t read phonetically irregular words

– Phonological dyslexia can read words by sight, but not on the basis of phonological analysis unable to read uncommon phonetically regular words or nonsense words can read all that have entered their sight vocabulary

– Deep dyslexia exemplified by reading jog for run, or bread for cake

LD (3)

• Cause of dyslexia several neurologically based causes that interact with non-biologically based causal factors prove to be the most useful guiding framework for understanding the reading problems confronted by children

LD (4)

• Dyscalculia impairment in the ability to perform arithmetic operations, may occur after lesions to the posterior regions of either left or right hemisphere (Grafman et al, 1982)– Language-based dyscalculia similar to the dyscalculia

seen after left-hemisphere lesions also having problems with spelling and reading, but not with visual or tactual perception

– Spatial dyscalculia right-hemisphere lesion – But, no definitive neuroanatomical causes!

LD (5)

• Non-Verbal LD difficulties in areas that are not explicitly verbal, and therefore, less emphasized in the academic environment heterogeneous, including impairment in the domains of perception, spatial processes and socio-emotional processing

• Hypothesis right-hemisphere dysfunction, possibly including white-matter connections

ADD • Behavioral features distractibility, impulsivity, and

restlessness often diagnosed in children and can extend into adulthood.

• Having great difficulty attending to relevant cues and information in their environment often act as if they are not listening, moving on to other tasks and finish nothing, highly disorganized, difficulty delaying gratifications , hyperactive motor behaviors (not always present), emotional immaturity, shallow social relationships, poor academic/work performance result in oppositionality

ADD (2)

• Not a unitary disorder, but a spectrum of disorders with overlapping symptoms

• Biological factors in ADD:– Neurotransmitters decrease in catecholamine

and indoleamine activity often given tricyclic antidepressants

– Genetic Factors no specific gene has been identified 30% higher risk if the parents are ADD themselves

ADD (3)

– Arousal Theories has no solid neurobiological evidence• Overarousal the filter systems in lower brain centers

fail to filter stimuli normally – so irrelevant information is not screened out leads to kind of cognitive shutdown cause ADD children unable to do selective attention to one particular stimulus • Underarousal higher brain centers do not receive

enough input from lower brain centers cause distractibility, hyperactivity and risk-taking behaviors

ADD (4)– Reward Theories due to disruption of brain reward

centers and/or with other parts of the brain cause ADD children unable to modify their behaviors, even if they know the consequences

– Motivation Theories dysfunctional in individuals with ADD cause them unable to stay on-task and to complete tasks that require sustained attention and effort in the absence of ongoing feedback or reward but, There’s no ADD while playing Nintendo (Barkley) immediate reinforcement against Reward Theories

ADD (5)

– Prefrontal cortex play a critical role in the planning, initiation and regulation of behavior disturbed in ADD • Disrupt working memory decrease capacity to profit

from experience, to anticipate the consequences of one’s actions, and to use these anticipations to guide future actions

Autism

• An extremely disabling disorder that almost always begins before age 30 months and lasts a lifetime, though sometimes with improvement

• Characterized by:– Severe impairment in verbal and non-verbal communication– Failure to develop social relationships – Stereotyped and repetitive patterns of behavior, interest

and activities • Tend not to seek comfort, not looking at their

caregivers, do not care if they are hold

Autism (2)

• Most children with autism are retarded and 75% have an IQ below 50 – however, some are with normal IQ scores

• Autistic savant when autistic child have a special talent or skill in specific area, such as: music, ability to memorize, art or the ability to perform calculations

• They lack a theory of mind a concept or sense that others have mind or consciousness unable to assume the perspective of others

Austism (3)

• Asperger’s syndrome they still able to introspect about their condition and tell others about it

• Causes:– Psychogenic theories autism is not correlated with

environment and personality of their parents– Genetic Factors 2%-3% of siblings of autistic persons

are themselves autistic – Other factors rubella, hydrocephalus, perinatal

complications, major organic disorders

Autism (4)

• Conclusions:– no specific brain abnormality or dysfunction that is

seen in all causes of autism – Autism is not a homogenous entity, but a group of

disorders (Hooper et al., 1993), each of which may be caused by different combinations of genetic factors and brain abnormality occurring early in development (Gillberg, 1992)