Lecture 2 Flashcards
(24 cards)
1
Q
What is neonatal handling?
A
- Removing rodent pup from mother for 15min a day for first 3wks of life induces a more efficient adrenocortical stress response later in life (moderate but brief)
- Smaller stress response
- Faster return to baseline = better recovery
- In older age: lower glucocorticoids concentrations and less neuron loss
- Called stress immunisation
- Introducing handling after 3 wks of age does not cause this effect
2
Q
How does postnatal experience effect HPA axis development?
A
- Postnatal handling represents a mild stimulation of the stress response early in life producing a more efficient response = can undo some of the harm prenatally
- Causes permanent changes to HPA axis system by increasing its sensitivity to the signal of circulating GCs, causing more efficient regulation of stress hormonal secretion
- These changes in pattern on receptors for stress hormones are lifelong
- Postnatal handling can attenuate fearfulness in novel environments and reverse increased emotional reactivity caused by prenatal stress
3
Q
What is the importance of a well-groomed child?
A
- Effects of postnatal handling on HPA axis development are mediated by mother-pup interaction: postnatal handling increases frequency of licking and grooming upon return and these maternal behaviours are associated with a reduced stress response
- Form of compensation of the stress
- Study showed there are 2 groups of animals: one having low grooming and little arch back nursing , and vice versa
- When animals are stressed for a short period of time: all animals response to stressor. Intensity and recovery is better in the group of higher levels of good quality care
4
Q
What is cross-fostering?
A
- Prenatally stressed pups were placed with adoption mother and compared to bio mothers with prenatally stressed pups
- Adoption increased maternal behaviour, foster mothers spent more time licking and picking up pups than bio
- Adopted pups show attenuated responsiveness of HPA axis to stress
- Good for child to expose self to smaller stress
- Variations in maternal behaviour serve as a mechanism for the non-genomic transmission on individual differences in stress reactivity across generations
5
Q
Can it be negative too?
A
- Postnatal factors are not only able to compensate for prenatal negative effects but can also be harmful.
- Maternal separation (3 hrs. or longer) - in contrast to much shorter handling - leads to an increased reactivity of HPA axis:- significant reductions in GC receptor density in hypothalamus, hippocampus, and frontal cortex, resulting in a decreased negative feedback sensitivity of the HPA axis;
- Hyper-secretion of GCs after maternal deprivation could predispose to development of depression and other stress-related mental
health problems
6
Q
What was the effect of maternal care of gene expression in offspring?
A
- Maternal behaviour affected GC receptor gene expression in the hippocampus through DNA methylation where genes are locked in the off positioned so cannot be expressed
- e.g if rat mum was not groomed/licked, enzymes off, and they have high anxiety and when they mother there would be low licking/grooming
- Claims to show the same processes occur in humans: behaviour of mother programs HPA axis
- Looked at hippocampus of suicide patients and they had decreased corticoids in the hippocampus
7
Q
What did Gunnar say?
A
- Early adversity disturbs attachment. Resulting in development of a disorganised/disorienting attachment, characterised by freezing, heightening risk for poor outcomes in childhood and beyond
- Preventative interventions focus on attachment, increasing parental sensitivity and responsiveness = why babies are adopted ASAP
8
Q
What was the social learning theory perspective?
A
- Behaviours are exhibited by neglected and abused children
- Poor relationships and a tendency to attribute hostile intent to others have been observed to maltreated children
- Preventative interventions attempt to avert child behaviour by training parents to use consistent non-hostile guidance and discipline
9
Q
What is the neurobiological model?
A
- Psychosocial models fall short of fully explicating why some individuals respond effectively to existing interventions and others not
- Why and how maltreatment affects brain development and increases risk of psych disorders
- Mechanisms through which psychosocial interventions operate and why individual differences in response to treatment and interventions exist.
- Attachment perspective focuses too much on mother and child - children can develop multiple, different types of attachment to others
- Model explains why secure stable attachments are important for brain development AND why they are long-lasting and difficult to undo
10
Q
What is the effect of maternal separation and social isolation?
A
- Tactile contact is a stronger determinant of attachment to a surrogate mother than feeding, and tactile deprivation was a critical determinant of autistic like behavioural syndromes that resulted from early social deprivation in macaques
- Towel-covered mother did not provide sufficient love to enable healthy development
- In later life, monkeys were either indifferent or abusive to other monkeys and had difficulty with mating and parenting
11
Q
What happened in Romania?
A
- Romania wanted people to have large families by banning contraception and abortions but families were poor, so they were put into care
- Institutionalised children lived in Leaganes in which their medical and nutritional needs were met but their psycho-social needs were not
- The children bore a resemblance to the behaviour or socially deprived macaques: muteness, blank facial expressions, social withdrawal and bizarre stereotypic movements
- Most children had experienced severe social/tactile deprivation due to high child:caretaker ratios
12
Q
What was a study looking at Romanian children Intervention?
A
- Able to randomly assign to enrichment condition (4:1) and compared them to 20:1
- During enrichment phase children accelerated in physical growth and mental-motor development
- When funding stopped and children went back to 20:1 = advantage disappeared
13
Q
What is cortisol?
A
- Not stable level but varies depending on time of day collected - levels are very high when you wake up and when you sleep, but drop over the day
- In Romanian children. Their cortisol levels did not vary and was flat
- In intervention, children had a slightly more varied but not normal rhythm
- Intervention had no effect on cortisol levels, orphanage-rearing had disturbed the normal pattern
- Rodent handling studies show presence of critical period for touch to regulate system
- Intervention may have begun too late to have pos effect on HPA or program was too short
14
Q
What was the study looking at salivary cortisol levels in children adopted from Romanian Orphanages?
A
- Children were adopted into other countries from these institutions
- She split ppts into adopted younger and adopted older = thought there would be more cortisol in older ones who had stayed for longer
- Research shows children with growth retardation under 2yo have higher baseline cortisol several years later = children with PTSD who experienced physical/sexual abuse have higher cortisol levels
- Tested cortisol for 3 days, 3 samples per day = had to live in Romania for 18mo, and living in their adoptive homes for at least 6y
- All developed normal-ish cortisol levels compared to Canadian children
- Later adopted children had higher cortisol levels linked to duration of time spent in institution
- Brain study in children in UK - compared same thing: these children have lived in the UK for a long time but there was still an effect of those conditions
15
Q
What was the study looking at exposure to postnatal depression predicts cortisol in adolescent offspring?
A
- Animal research shows that early adverse experiences result in altered GC levels in adulthood pr increased response to stress
- Maternal postnatal depression is associated with a variety of adverse outcomes
- Offspring of depressed mothers are themselves at higher risk for depression = looking at biological mechanisms in intergenerational risk
- Looking at saliva cortisol measured in adolescents who were or were not exposed to maternal depression = predicting maternal PND associated with elevated morning cortisol
- 48PND families and 39 controls = mean difference is higher in PND than controls in the morning, and slight increase but not significant in evening
- No diff in cortisol within PND group between those with/without a currently depressed mother
- Maternal PND significantly predicted variance in 8AM cortisol measures over and above child gender, depressive status, breast feeding and Tanner stage
- Availability of sensitive caregiver serves to buffer HPA responses to env demand in dev. Infant
- Shows maternal PND is enduring
16
Q
What are the effects of normal variations in maternal behaviour on infant cortisol? (Maternal sensitivity)
A
- Looked at mother child interactions and sensitivity and how this effects infant cortisol
- 1292 6mo infant-mums
- Emotional challenges, three saliva samples: baseline, 20 & 40 mins
- 2nd home visit involved semi-structured interaction between mother and child
- Children of high MS mothers exhibited lower baseline cortisol as well as greater emotional reactivity and better regulation in response to challenge
- Children of low sensitivity had higher baseline cortisol and decreasing cortisol at 20/40min
- Normal variations in MS are associated with child HPA axis reactivity and regulation in response to challenge
17
Q
What are the three levels of stress neurobiology?
A
- Corticolimbic: processes anticipated threats and orchestrates behavioural/emotional responses
- Hypothalamic-brainstem level: coordinates responses to both corticolimbic input and direct, less-processes homeostatic threats
- Neural-to-adrenal level: activates the endocrine system, especially the release of glucocorticoids and epinephrine
18
Q
What is the Role of Corticotropin-Releasing Factor?
A
Coordinates behavioural, automatic, emotional and hormonal stress responses
19
Q
What are the CRF pathways?
A
1) CRF neurons in the PVN stimulate HPA axis = ACTH release = cortisol and glucocorticoids released
- This maintains brain sensitivity and manages stress recovery and memory of threats
2) CRF neurons in CeA anticipate threats and activate HPA axis through indirect pathways
- Stimulate locus coeruleus to release norepinephrine, enhancing alertness and emotional reactivity
20
Q
What is the importance of timing?
A
- In rats, brain development parallels late gestation in humans
- GR dene regulates stress through HPA and is inactive at birth in rats
- Maternal care promotes activation of GR gene = high care mothers produce resilient offspring with more active GR genes
- Disruptions to maternal care early have stronger and more lasting effects than later ones
- Peripubertal changes can reduce some behavioural outcomes but cannot reverse GR deactivation
- Only pharma treatments can activate the GR gene in adulthood = plays central role in lifelong stress vulnerability
21
Q
What is the Stress Hyporesponsive Period?
A
- Is a developmental phase in rodents where HPA axis is minimally reactive to stressors = to protect developing brain from bad effects of elevated glucocorticoids
- Emerging evidence for a similar period in humans after a year old
- Maternal behaviours maintain this period = caregiver quality in humans can buffer stress
22
Q
What is an example of caregiver quality buffering stress?
A
- Securely attached toddlers show no cortisol rise during stress-inducing tasks BUT insecure toddlers show significant increase
- Infants of less sensitive caregivers have larger cortisol responses to stress as toddlers
- Low response caregiving is linked to fearfulness, anxiety and depression
23
Q
What do Resilient Individuals show?
A
- Low baseline stress system activity
- Higher ACTH response to CRF challenge suggests low chronic CRF exposure
- Normal to blunted cortisol and heart rate indicate reduced adrenal sensitivity to ACTH = either protective or vulnerability to future stress-induced pathology
24
Q
What do adults with depression or PTSD show?
A
- Both disorders show central CRF hyperactivity and blunted ACTH responses to pharmacological challenge
- Depression: reduced neg feedback: higher cortisol, poor suppression
- PTSD: increased negative feedback: lower cortisol, enhanced suppression
