Quantitative Measurement of Sensory Dysfunction in Children with Cognitive Disabilities

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• Quantitative Measurement of Sensory Dysfunction
  in Children with Cognitive Disabilities

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• Laura J. Meyer, Lucy Jane Miller, Daniel N.
  McIntosh, Sally Rogers, and Randi J. Hagerman
• University of Colorado Health Sciences Center
• Departments of Rehabilitation Medicine
• and Pediatrics

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Abstract

• Electrodermal responses (EDRs) to sensory stimuli
  were examined in individuals diagnosed with
  fragile X syndrome and sensory modulation
  disorder. Theory and clinical observation suggest
  that their responses should be larger than that
  of non-affected people. However, there has been
  little experimental work on hyperarousal and
  sensory sensitivity in these groups. We
  established a laboratory method for examining
  generalized sensory defensiveness.

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Abstract (contd.)

• Individuals with fragile X syndrome showed
  greater EDR amplitude, more responses per
  stimulation, EDRs on a greater proportion of
  trials, and lower rates of habituation than age
  and gender-matched controls.
• Individuals with autism show diverse EDR patterns
  after sensation. There is a small group of
  non-responders and a small group of
  hyper-reactive responders. In addition, about one
  third of our pilot sample had EDR responses
  within normal limits.

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• Participants
• Study 1 Males with the fragile X mutation (n
  15) and age matched control males.
• Study 2 Ten individuals with Autism and age and
  gender matched control group (M age 16range 5
  to 53 years 8 male, 2 female).

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Sensory Challenge Protocol

• To gauge individuals responses to stimulation,
  we created a laboratory paradigm during which
  experimenters presented sensory stimulation while
  EDA was recorded continuously. There were ten
  trials in each of five sensory systems
  administered in the order below. Each stimulation
  takes approximately 3 seconds, and they are
  presented on a pseudo-random schedule 12 or 17
  seconds apart. Ten of each type are presented
  before moving to the next modality.

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Sensory Challenge Protocol (contd.)

• Olfactory (wintergreen oil in vial 2 waved 2.5
• cm below nose)
• Auditory (fire engine siren, 90-decibels)
• Visual (20 watt strobe light at 10 flashes per
• second)
• Tactile (a feather is gently run from the
• participants right ear canal, along chin lie to
• bottom of chin, and finally raised to the
• childs left ear)
• Vestibular (childs chair is smoothly and
• slowly tipped back to a 45 degree angle)

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Electrodermal Responses

• Electrodermal activity (EDA) assessed extent to
  which individuals respond to stimuli. EDA changes
  in the presence of startling or threatening
  stimuli, aggressive or defensive feelings
  (Fowles, 1986), and during positive experiences.
  Measuring skin conductance indirectly assesses
  SNS activity (Andreassi, 1989). (See Fowles et
  al., 1981 for methods and Dawson, et al., 1990
  for scoring.)

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Electrodermal Responses(contd.)

• Variables were
• amplitude of the main (largest) peak in
• response to each stimulus
• number of responses for each stimulus
• and
• participants mean probability of
• responding to all five sensory stimuli at
• each trial.

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Fragile X Syndrome

• Although fragile X syndrome is well known for
  causing cognitive disabilities or learning
  disabilities, it also causes behavior problems
  including hyperarousal, hyperactivity,
  aggression, anxiety, tantrums and extreme
  sensitivity to sensations (Hagerman, 1996b). The
  observed hyperarousal may be partially related to
  strong reactions to sensory stimuli such as
  noises, touch, visual and olfactory stimuli
  (Hagerman and Cronister, 1996). We hypothesize
  that people with fragile X syndrome will show
  higher amplitude EDRs, more EDRs, and slower
  habituation to stimulation than seen in the
  control group.

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Figure 1 EDA profile of a normal control
(responses to 10 olfactory stimuli). Amplitude is
in micromhos. Note lower amplitudes of EDR, one
main peak after stimuli, and definite habituation.
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Figure 2 EDA profile of an individual with
Fragile X Syndrome (response to 10 olfactory
stimuli). Amplitude in micromhos. Note large
amplitudes, numerous reactions, and a lack of
habituation.
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Figure 3 Mean amplitude in log10 (micromhos) of
responses to each trial, presented separately for
Fragile X and Control participants. Significant
effects Group Trials
Miller et al., 1999
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Figure 4 Mean number of responses to each trial,
presented separately for Fragile X and Control
participants. Significant effects Group Trials
Miller et al., 1999
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Figure 5 Mean proportion of trials during which
responses were greater than .05 micromhos,
presented separately for Fragile X and Control
participants. Significant effects Group
Trials Group x Trials
Miller et al., 1999
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AutismPrevious Literature on EDR
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Figure 6 Mean amplitude in log10 (micromhos) of
responses to each trial, presented separately for
Autistic and Control participants. Significant
effect of trials
Miller et al., 2001
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Discussion

• This study provides psychophysiological evidence
  that individuals diagnosed with fragile X
  syndrome and autism show differential responses
  to sensory stimuli, as indexed by EDR.

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Discussion (contd.)

• 1. This pattern of sensory over-reactive is not
  simply due to cognitive delay or behavioral
  problems. Individuals show atypical
  responsiveness, which is different than controls
  (Martinez-Silva et al., 1995).

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Discussion (contd.)

• 2. There appears to be a subgroup of disorders
  that show this pattern further work needs to
  investigate the possible connections among these
  disorders. Individuals with autism sometimes show
  hyper-responsive and sometimes hypo-responsive
  EDA patterns.

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Discussion (contd.)

• 3. Our findings support an intrinsic and
  physiologically based enhancement of reactions to
  sensations in boys with fragile X syndrome.
  Because EDA indexes SNS activity, the present
  data demonstrate that the SNS is affected. This
  ponts to the need for additional research on the
  physiological and anatomical underpinnings of
  abnormal responses to sensory stimulation.

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Discussion (contd.)

• 4. Our findings support a physiological
  underpinning of sensory modulation disorder. As
  with fragile X syndrome, that EDA is affected in
  children with autism suggests that the SNS is
  affected.

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Discussion (contd.)

• 5. The role of anxiety needs to be examined.
  Clinically, increased sensory responsiveness may
  also be related to the anxiety or aversive
  responses that occur with direct eye contact,
  light touch, or loud sounds. Anxiety is
  intrinsically tied to hyperarousal (Hagerman,
  1996b). Further research should explore whether
  it is actually generalized anxiety or specific
  anxious reactions to sensory modulation disorder.

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Discussion (contd.)

• 6. EDRs could be used in studies of the
  effectiveness of interventions for disorders
  showing these EDA profiles (Hagerman, 1996a
  Reisman and Gross, 1992).

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Acknowledgements

• We wish to thank the Wallace Research Foundation
  for primary support of this research. In
  addition, support was obtained from Sensory
  Integration International for psychophysiological
  equipment, March of Dimes Grant 0492, and MCH
  Grant MCJ-08-9413. We also wish to thank the
  Kids Helping Kids Program of The Childrens
  Hospital Research Institute. The support of Dr.
  Dennis Matthews and other staff and faculty at
  The Childrens Hospital, Department of
  Rehabilitation in Denver is greatly appreciated.

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Acknowledgements (contd.)

• We value the work of Jan Ingebrittsen in writing
  the KIDcal program, and of Tara Wass in
  information management. Finally, the dedication
  of evaluating occupational therapists and lab
  experimenters was invaluable Margaret Frohlich,
  Patricia Kenyon, Nicki Pine, Robin Seger, Clare
  Summers, Sharon Trunnell, Molly Turner, Lisa
  Waterford, and Julie Wilbarger.