THE ROLE OF THE VAGAL SYSTEM IN THE SENSORY PROCESSING PATTERNS OF CHILDREN WITH

AUTISTIC SPECTRUM DISORDERS

Catherine Cavaliere, PhD, OTR/LNew Jersey Occupational Therapy

Association Annual ConferenceOctober 1, 2011

The Beginning…

Clinical Hypothesis: “ Sensory integration intervention fosters

neural adaptations that thereby support behavioral adaptations within the environment in children with autistic spectrum disorders(ASD).”

Core assumption of SI theory: “The goal of sensory integration intervention

is to improve the efficiency of the nervous system in interpreting sensory information for functional use.” (Parham & Malliouz, 2000)

Treatment efficacy study – pre/post test - measure of neurophysiologic change

The Middle

Lack of research to support the theoretical assumption that SI intervention fosters neural change

Lack of information in literature as to how children, with and without autism, respond to sensation, neurophysiologically, PERIOD!

The End…The Beginning! “How do children with

ASD respond to sensation neurophysiologically? Is there a relationship between this and their behavioral responsivity to sensation?”

Measure and methods

Dr. Lucy Jane Miller and colleagues – Sensory Challenge Protocol (SCP)

Autistic Spectrum Disorder (ASD)

DSM IV Social Interaction

Marked impairment in nonverbal behavior Failure to develop age appropriate peer relationships Lack of spontaneous seeking to share interests with others Lack of social or emotional reciprocity

Communication Delay in or lack of spoken language Marked impairment in conversational skills Stereotyped use of language Lack of age appropriate pretend or social play

Stereotyped Patterns of Behavior At least one restricted pattern of interest Inflexible adherence to routines Stereotyped or repetitive motor mannerisms Preoccupation with parts of objects

(American Psychiatric Association, 1994)

Behavioral responses to sensation in children with ASD

70-97% of children with ASD – atypical patterns of sensory processing (Ornitz, 1989; Adrien et al., 1992, Eaves et al., 1994; Kientz and Dunn, 1996; Greenspan and Wieder, 1997; Tomcheck and Dunn, 2007)

Children with ASD – early signs of deficits in sensory processing – central to ASD diagnosis (Baraneck, 1999)

Children with ASD respond differently to sensation, behaviorally, than do children without ASD (Dunn and Kientz, 1996; Dietz and White, 2000)

ASD – most severe sensory processing disorders (Bagnato and Neilsworth, 1999)

Physiologic responses to sensation in children with ASD

Patterns of physiological responsivity (EDA) that are different than typically developing children and other groups of children with behavioral difficulties with sensation

Decreased magnitude of EDR – hypo-responsivity (Miller et. al., 2000)

2 groups – High arousal – higher magnitude EDR; Low arousal – lower magnitude EDR – heterogeneous group ( Schoen,S.A, Miller, L.J., Brett-Green, B., &Hepburn, S.L., 2008)

Lower vagal responses to auditory and tactile information (Schaaf and Benevides, 2006)

(McIntosh, D., Miller, L. J., Shyu, V., & Hagerman, R., 1999; Miller et al., 1999; Donelon,- Mangeot et al., 2001; Miller, L.J., McIntosh, D.N., Reisman, J.E., Simon, J., 2001; Schaaf , R.C.,& Benevides, T., 2006; Schoen, S.A, Miller, L.J., Brett-Green, B., &Hepburn, S.L., 2008)

“The objective of therapy for the autistic child is to improve sensory processing so that more sensations will be effectively “registered” and modulated, and to encourage the child to form simple adaptive responses as a means of helping him to learn and to organize his behavior… As we continue to treat autistic children, we shall find out more about their neurologic problems and develop ways of “reaching” their brains with sensory experience.”

(Ayres, 1979)

Neuro-physiologic state

Behavioral state– attention, arousal

Adaptive Interactions

Occupational Performance

Theoretical PerspectiveNeuro-occupation (Padilla & Peyton, 1997)

Physiologic Measures

Autonomic Nervous System

Parasympathetic Nervous System

Restorative

functions

Cardiac Vagal

Tone

Respond to all environmental situatio

ns

Sympathetic Nervous System

Highly active stressful

situations

Electrodermal

Activity

Cardiac Vagal Tone (CVT)

Parasympathetic nervous system’s (PsNS) modulation of heart rate via the vagus nerve

Respiratory Sinus Arrhythmia(RSA) - rhythmic heart rate variability within spontaneous breathing

2 functional aspects of CVT: Baseline – rest – high CVT Vagal regulation – change from baseline to respond to

environment – drop in CVT

More variability indicating more efficient neural control physiologically able to meet the demands of

any situation – adaptive interactions

(Porges, 1992; 1995)

Physiologic Variability and Adaptive Interactions

Physiologic

Variability

Physiologic

Flexibility

Behavioral

Flexibility

Adaptive Interactio

ns

(Porges, 1992;1995)

Porges (1995)

Healthy Neonates High Risk - NICU

Baseline Vagal Tone

Higher baseline VT correlated with greater self-regulation and more positive developmental outcomes

( Porges et al, 1996; Fox, 1989; DeGangi et al, 1991; Fox and Porges, 1985; Huffman, L.C., Bryan, Y.E., delCarmen, R., Pedersen, F.A., Doussard-Roosevelt, J.A. & Porges, S.W., 1998; Gunnar, M.R., Porter, F.L., Wolf, C.M., Rigatuso, J. & Larson, M.C., 1995; Stifer and Fox, 1990; Richards, 1985)

Fragile x– lower baseline (less heart rate variability) VT than boys without (Boccia &Roberts ,2000)

SMD – lower baseline vagal tone than children without (Schaaf et al., 2003;

2010)

ASD – lower baseline vagal tone than typically developing children (Schaaf and Benevides, 2006)

Significant relationship between vagal tone and adaptive behaviors - ASD - lower vagal tone had less adaptive behaviors (vineland adaptive behavior scales) (Schaaf and Benevides, 2006)

Vagal Regulation

More consistency in suppressing vagal tone in response to environmental stimuli/task, the greater the social and attentional capacities and more even temperament

(Porges et al, 1996; Huffman et al, 1998; Fox, 1989; Calkins, 1997; Suess, P.E., Porges, S.W. & Plude, D.J, 1994; DeGangi et al., 1991;Gunnar et al., 1995; Stifter and Fox.,1990; Richards, 1987 )

Reliability of Baseline Vagal Tone

Author Subjects - age Testing period Results - VT

Fracasso et al., 1994

5,7,10,13 months

Every 3 months – 4 testing sessions

Moderate stability (r=.50-.55)

Stifter & Fox, 1990

Neonates, 5 months

5 months apart – 2 testing sessions

Not Stable (r=.07)

Fox & Field, 1989

3yrs 6 months apart - 2 testing sessions

Stable (r=.89)

Calkins & Keane, 1994

2 yrs, 4.5 yrs 2.5 years apart – 2 testing sessions

Moderate stability (r=.57)

Doussard-Roosevelt et al., 2003

5-6yrs 2 wks apart – 3 testing sessions

Moderate stability (r=.58)

Porges, 1992 NICU Neonates

first day off ventilator, every day for 5 days – 6 testing sessions

Stable (r=.90)

Reliability of Vagal Regulation

Author Subjects Task Results - VT

Calkins & Keane, 2004

2yrs, 4.5yrs Attention, empathy, frustration, problem solving

No stability (r=.05-.29)

Doussard-Roosevelt et al., 2003

5 yrs – once a wk – 4 wks

Negative affect elicitor task

Modest stability wks 1-2 (r=.40)No stability second 2 wks (r=.08-.25)

El-Sheik, 2005 9,11 yrs Cognitive taskEmotional task

Stability – cognitive task – (r=.60)No stability – emotional task – (r=.06)

Synthesis of Research on Vagal Tone

Infants/ young children with high baseline vagal tone demonstrate greater self-regulation

Children with ASD and SMD have lower baseline vagal tone than children without

Infants/ young children who consistently suppress vagal tone in response to a challenge demonstrate greater attentional and social interaction skills and more even temperament

Reliability– mixed results

Gaps in the Literature

Reliability of vagal tone has not been established

Limited information on vagal tone in older children (4+)

Limited information on vagal tone in various diagnostic groups including autism

Inconclusive information on the relationship between physiologic responsivity(CVT) and behavioral responses to sensation

Research Questions

Is cardiac vagal tone a reliable measure of physiologic responsivity to sensation in both typically developing children and children with ASD?

Do children with ASD respond differently (behaviorally and physiologically) to sensation than typically developing children?

Is there a relationship between the behavioral and physiologic responses to sensation in children with and without ASD?

Short Sensory Profile (SSP)(Dunn, 1997)

Sensory Profile (Dunn, 1999)

Caregiver questionnaire Profiles a child’s behavioral responses to

sensation Construct validity – sensory processing (Dunn, 1997)

Discriminant validity - differentiate children with ASD from children without autism, ADHD, SMD (Kientz &Dunn, 1997; Ermer & Dunn, 1998)

Positively correlate with physiologic measures of sensory responsivity (EDR) using the SCP (Miller et al.,1999;2000)

Design

Test re-test/ Multifactorial repeated measures design

Independent variables Group Sensation (SCP) Testing session

Dependent variables Physiologic responsivity to sensation (CVT) Behavioral responsivity to sensation (SSP)

Inclusion Criteria

Experimental group Males with ASD - 4-11 yrs. No other developmental/neurological conditions No medications

Control group Typically developing males – 4-11 yrs. No developmental/neurological conditions No medications

Subjects

39 boys (16 typically developing; 23 with ASD) Excessive artifact (n=5) Technical Difficulties (n=3) Inability to tolerate testing (n=4)

15 typically developing boys; 11 boys with ASD Typically developing (TD)– 8.7 years ASD – 7.3 years

Instrumentation

Psylab stand alone monitor (SAM) acquisition and analysis system (Contact Precision Instruments) Heart rate and electrodermal responsivity Synced with the Sensory Challenge Protocol

MxEdit analysis program (S.Porges,1985)

heart rate converted to vagal tone index artifact identification and editing

Sensory Challenge Protocol (SCP) (Miller,

1999)

Five domains of sensation (vestibular, auditory, visual, olfactory, tactile)

10 trials of each sensation – 3 secs per trial 15-19 sec. between each trial – random intervals 20 secs between domains Baseline and Recovery 15 mins without stopping Testing can be paused Domains can be skipped

Procedures

Meet/greet parents; complete forms Acquaint child with testing environment Explain testing procedures in age appropriate

language Child signs assent Child seated - electrodes placed on child SCP started End of SCP child picks a small gift

Data Analysis

Question 1: Is cardiac vagal tone a reliable measure of responsivity to sensation in typically developing children and children with ASD?

Intraclass correlation Coefficient (ICC) Baseline measures of cardiac vagal tone Vagal changes in response to sensations

Data Analysis

Question 2: Do children with ASD respond to sensation (behaviorally and physiologically) differently than typically developing children?

Repeated Measures ANOVA – within group patterns of responsivity

Multivariate ANOVA – between group differences – SCP and SSP

Data Analysis

Question 3: Is there a relationship between physiologic and behavioral responses to sensation in children with ASD and typically developing children?

Pearson Correlation Coefficient –vagal scores SCP and SSP scores

Results

Question 1: Is cardiac vagal tone a reliable measure of responsivity to sensation in typically developing children and children with ASD?

Table 1. Test Re-test Reliability Measures.

SCP Domain _________________________________________________________

Total Typical ASD

M SD ICC M SD ICC M SD ICC

Baseline 6.36 1.20 .830 6.80 .981 .702 5.77 1.27 .889

Tones 6.57 1.16 .782 7.0 .933 .525 6.01 1.25 .905

Visual 6.59 1.05 .830 6.91 .847 .650 6.11 1.71 .911

Sirens 6.59 1.01 .828 7.01 .775 .724 6.03 1.07 .819

Olfactory 6.42 1.24 .920 6.91 .929 .923 5.74 1.33 .881

Tactile 6.55 1.17 .912 7.0 .779 .810 5.85 1.27 .916

Vestibular 6.76 1.11 .916 7.31 .711 .837 6.01 1.13 .896

Recovery 6.42 1.17 .851 6.90 .899 .710 5.77 1.21 .899

Av. Response 6.57 1.11 .894 7.04 .865 .801 5.94 1.18 .901

______________________________________________________________________________

Results

Question 2: Do children with ASD respond to sensation (behaviorally and physiologically) differently than typically developing children?

Baseline Vagal Tone

Baseline - t(20)=2.58, p=.018 ASD – lower baseline vagal tone – less

heart rate variability at rest Covariate

TYP (M=6.80, SD=.981) ASD group (M= 5.77, SD=1.27)

Figure 1. Within group vagal response patterns.

F=3.04, p=0.13

Figure 2. Between group differences in vagal responses.

P=.008

Table 2. Between group differences on SSP.

SSP Sig._(a)__TYP ASD M SD M SD

SSP total 175.0 15.4 128.0 16.4 .000Tactile 32.3 2.5 28.4 5.1 .013Taste/Smell 18.5 5.5 11.6 6.2 .011Movementsensitivity 13.8 2.4 14.6 .81 .298Under resp./ 32.3 3.0 18.3 4.2 .000seeks sensationAuditory Filter 26.9 2.9 17.0 5.7 .000Low energy 28.6 4.1 21.6 7.7 .012Visual Auditory 24.2 1.7 16.4 4.5 .000

___________________________________________________________________a Adjustment for multiple comparisons: Bonferroni

Results

Question 3: Is there a relationship between physiologic and behavioral responses to sensation in children with ASD and typically developing children?

Table 3. Correlations between SSP sections and vagal responses on SCP domains.

SSP SCP domain r_______________TYP/ASD sessions combinedSSP total vestibular .510Auditory vestibular .526Visual/auditory vestibular .668Visual/auditory olfaction .509Visual/auditory tactile .558Visual/auditory av. response .542 Visual/auditory vestibular .569

ASD sessions combinedVisual/auditory tones .627

ASD session 2Visual/auditory sirens .555Visual/auditory olfaction .606Visual/auditory tactile .551Visual/auditory vestibular .708 Visual/auditory av. response .613________________________________________________________________________

Correlations

ASD - 99.9% of the vagal responses to sensations across sessions were correlated (<.75) – Ex: visual 1 to olfaction 2

Little physiologic variability across time and across sensations

TYP- 77.5% - more variability across time and across sensation

Discussion: Reliability of CVT

Overall high stability

ASD - high stability – little variability across time (.819-.916)

TYP- mixed stability – more variability across time (.525-.923)

Discussion: Group differences in baseline vagal tone

ASD – sig. lower baseline vagal tone than TYP – less heart rate variability at rest

Supports previous findings (Schaaf et al., 2003; 2010)

Supports reliability findings- pattern of less physiologic variability - ASD

Physiologic Variability and Adaptive Interactions in ASD

Less Physiolo

gic Variabilit

y

Less Physiolo

gic Flexibilit

y

Less Behavior

al Flexibilit

y

Rigid/ inflexibl

e behavio

rs

Decreased

Adaptive

Interactions

(Porges, 1992;1995)

Discussion: Group differences in vagal responsivity.

F=3.04, p=0.13

Why Vestibular???

Vestibular system – central integrator (Cool, 1987) -

Spatial map – body, head, position and orientation - understand our environment in relation to self

“reference base “against which all sensory input and motor output must be evaluated ( Cool, 1987)

CN VIII - posterior parietal lobe (cerebellum and brainstem)

“bridge” between sensory inputs and motor outputs (Ayres, 1979)

Only sensory system that also has direct motor innervations (CN VIII) at spinal level – muscle tone and arousal – low in ASD (Miller et. al, 2001)

Why Vestibular???

Stereotyped behaviors – body sense driven (vestibular, proprioceptive and tactile)

Vestibular - critical role as central integrator

Examples: body rocking, head banging, darting, rigid inflexible

Stereotyped behaviors - seeking out vestibular stimulation (Bender, 1947, 1956).

Clinically – stereotyped behaviors - child’s attempt to seek out vestibular input

Treatment – large vestibular component

Goals of treatment - modulate arousal; increase body awareness; improve sensory modulation; attention and interaction

Why Vestibular???

ASD - demonstrated hypo-responsivity to sensation (Miller et. al., 2000)

Our findings support this – physiologic hypo- reactivity to vestibular information as compared to TYP

Results - provide preliminary evidence to support this clinical assumption : Stereotyped behaviors - fulfill a need for additional vestibular input in order to make sense of their environment

Discussion: Group differences in behavioral responses to sensation

ASD – sig. lower scores on all sections of SSP except movement sensitivity - TYP scoring lower

Vestibular Based – body position, orientation Questions related to safety awareness:

“ Becomes anxious/distressed when feet leave ground”“Fears falling or heights”“Dislikes activities where head is upside down”

TYP –more behaviorally sensitive to movement because they more efficiently react to vestibular information thereby providing them with a greater safety awareness and better body awareness

ASD patterns of response to vestibular information

Stereotyped

Behaviors

Less physiolog

ic reactivity

to vestibula

r

Less behavior

al reactivity

to vestibula

r

Seek out vestibular input

Discussion: Relationship between physiologic and behavioral responses to sensation

SSP SCP domain r_______________TYP/ASD sessions combinedSSP total vestibular .510Auditory vestibular .526Visual/auditory vestibular .668Visual/auditory olfaction .509Visual/auditory tactile .558Visual/auditory av. response .542 Visual/auditory vestibular .569

ASD sessions combinedVisual/auditory tones .627

ASD session 2Visual/auditory sirens .555Visual/auditory olfaction .606Visual/auditory tactile .551Visual/auditory vestibular .708 Visual/auditory av. response .613________________________________________________________________________

Why Visual/Auditory???

Visual/auditory section- single sensory system “holds hands over ears to protect from loud sounds” “is bothered by bright lights” “covers or squints eyes to protect from light”.

Other sections – multimodal “has a weak grasp” “has difficulty paying attention” “has difficulty standing in line close to other people”

SCP domains – single system based

Multimodal sensory experiences to SCP

Discussion: Relationship between physiologic and behavioral responses to sensation

Children with autism demonstrated less reactivity to vestibular information both physiologically (vagal responses )and behaviorally (score on movement sensitivity section)

Support this clinical assumption that the stereotyped behaviors - fulfill a need for additional vestibular input in order to make sense of their environment

relationship between physiology and behavior

Limitations

Small sample size Not age matched Initial testing anxiety

Conclusions

Preliminary info on reliability of vagal tone

Differences in physiologic responsivity between groups – ASD less physiologic variability

Relationship between physiology and behavior

Conclusion

Combined these findings provides preliminary evidence to support the theoretical and clinical assumptions that neurophysiologic state affects behavior

Directions for Future Research

Replicated - larger sample size Compare these results to SNS measures Modify the SCP to include some

multimodal sensory experiences *Intervention studies

“The objective of therapy for the autistic child is to improve sensory processing so that more sensations will be effectively “registered” and modulated, and to encourage the child to form simple adaptive responses as a means of helping him to learn and to organize his behavior… As we continue to treat autistic children, we shall find out more about their neurologic problems and develop ways of “reaching” their brains with sensory experience.”

(Ayres, 1979)

Acknowledgements

Dr. Genevieve Pinto-Zipp, EdD, PT Dr. Susan Simpkins, EdD, PT Dr. Valerie Olsen, EdD, PT Dr. Raju Parasher, EdD, PT Barbara Schupak, OTR/L, MPH Michele Parkins, MS/OTR/L

Acknowledgements

Dr. Lucy Miller, PhD, OTR/L Dr. Roseann Schaaf, PhD, OTR/L Teal Benevides, MS/ OTR/L

Celebrate the Children School - Michele Parkins, MS/OTR/L

Pediatric Therapeutics – Missy Briody, MS/OTR/L

Bergen Pediatric Therapy – Lisa Koo, MS/OTR/L

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