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Brain development = Behavioral development? (psychiatric comorbidity…
Brain development = Behavioral development?
Critical periods
Adolescence
gap between affective experience and ability to regulate arousal and motivation
improvements: more self-directed and self-regulating mind, deductive reasoning, information processing, expertise, hypothetical thinking
worse performance in real-life problems
Hot Cognition: influenced by feelings and social interactions
incomplete maturation of frontal lobes --> increased potential for risk-taking, recklessness, emotional problems
cognitive development correlates with age
development of arousal, motivation, emotion linked to pubertal maturation rather than to age
increases in sensation seeking, risk taking, recklessness correlates with puberty and not with age
Childhood
Intellectual ability 10 years after TBI
persisting consequences due to immaturity of the brain
may disrupt ongoing brain development
severe TBI: reduced intellectual ability, impaired attention, memory, slow processing speed, academic failure
more likely to have impaired non-verbal skills
no significant dose-response relationship
no significant effect of age at 10 years post TBI
early TBI
impaired non-verbal skills, attention, working memory issues
age of injury most closely associated with fluid cognitive skills
recovery consistent across groups, regardless of injury severity or age
deficits present at 12 months post TBI persist, indicator of longterm outcome
Example: Impairment of social & moral reasoning related to early brain damage in human PFC
progressively disruptive behavior
failed to complete assigned tasks, unresponsive to punishment, stealing, shoplifting, abusive, no friends, risky sexual behavior
no guilt, little evidence of empathy, insensitivity to child, denial of difficulties with behavior
bilateral, ventromedial or right PFC
adult-onset individuals at least can retrieve factual knowledge and feel remorse
also less severe symptoms
impaired decision making and social behavior but preservation of intellect
Two patients with lesions before 16 months: syndrome resembling psychopathy, impaired social behavior despite normal basic cognitive abilities
impaired acquisition of social conventions and moral rules
did not learn strategies & rules from repeated experience & feedback eg. Wisconsin Card Sorting Test, Tower of Hanoi
moral reasoning at pre conventional stage (like 10-year olds)
Gambling task: persisted in choosing options with high immediate reward but high longterm loss
differed from the typical psychopath: aggression was impulsive and not goal-directed
Clinical Implications
Autism
larger frontal & temporal GM volumes and slower growth rate in those regions
COS
resembles AOS
global GM loss similar to normal development but accelerated
hemispheric asymmetry of growth rates: right slower than left
parietal GM loss
Bipolar
cortical GM gain in left temporal cortex
GM loss in right temporal & subgenus cingulate cortices
tissue growth of white matter & ventricles
Alzheimer
retrogenesis
Functional maturation
back-to-front
Primary functions eg. primary motor cortex
Complex functions e.g.. temporal lobe
Motor & Sensory (Parietal)
Spatial orientation, speech, language
Executive function, motor coordination (Frontal)
Integration of memory, object recognition etc. (superior temporal cortex)
Heteromodal nature of cognitive brain development
Gray matter
nonlinear, inverted U-shape
in prepuberty increase, in post puberty decrease
loss correlated with synaptic pruning
White matter
linear increase until 40s
Plasticity
more myelin = less plasticity
plasticity-dependent synaptic pruning
Factors that influence behavior after brain damage
preinjury, social factors, injury age, family function
psychiatric comorbidity following TBI
Major Depression
44.3% of TBI cases
limited understanding of biological mechanisms involved
associated with socioeconomic factors & premorbid characteristics
may be indistinguishable from depression after general trauma
associated with poorer functional outcome & reduced social integration
prevalence rates highest during the 1st years following injury
Bipolar
4.2% of TBI cases
Schizophrenia
0.7% of TBI cases
Substance Abuse
22% of TBI cases
minimal shorterm risk factor
more often a consequence than a cause
Generalized Anxiety Disorder
9.1% of TBI cases
temporal pattern of onset is variable
risk remains for years following the injury
Panic disorder
9.2% of TBI cases
contributor: slowly evolving psychological reaction to injury
PTSD
14.1% of TBI cases
OCD
6.4% of TBI cases
mixed results
"It is unclear whether the major contributing factor for development of psychiatric syndrome is the physiological consequence of brain injury or the psychological response to trauma and disability due to the injury"