The relationship between sensory defensiveness, anxiety, depression and perception of pain in adults

Headnote

ABSTRACT. The impact of sensory defensiveness on performance, behaviour and adjustment of children has been addressed in the literature, but little has been written concerning its impact on adults. The purpose of this study was to explore whether sensory-defensive adults had more symptoms of anxiety, depression and pain than adults without sensory defensiveness. Participants were 32 volunteers who were normal functioning adults aged 21 to 48 years, without physical or psychological diag noses or history of abuse. They were screened to eliminate persons with undiagnosed psychological problems using the Forty-eight Item Counseling Evaluation.

Participants were assigned to a sensory-defensive or non-sensory-defensive group based on their score on the ADULT-SI, a sensory history interview, which assesses sensory defensiveness in adults. The two groups were matched for age, gender and race. Participants were then administered the IPAT Anxiety Scale, the IPAT Depression Scale and the Pain Apperception Test. Differences were found between sensory-defensive and non-defensive and non-defensive adults in anxiety (p=0.014) and depression (p=O.019), but not in pain perception. Analysis of the screening scores of the Fortyeight Item Counseling Evaluation indicated an unexpected difference between groups in psychological adjustment (p=0.005). This study supports clinical impressions that sensory-defensive adults differ from non-defensive adults in some psychological parameters. A sequela of sensory defensiveness in adults may be a tendency towards increased symptoms of anxiety and depression. Further, investigation of sensory defensiveness and its sequelae in adults is recommended, using larger samples, more sensitive tools and various diagnostic categories. Exploration of the impact of sensory defensiveness on adult roles and performance and life satisfaction is also recommended.

Key words: sensory defensiveness, tactile defensiveness, sensory integration, sensory processing.

Introduction

Sensory defensiveness is described by Royeen and Lane (1991) as a modulation disorder in the processing of sensory input by the central nervous system, which is characterized by hypersensitivity, over-orienting and aversion.

Modulation is one of three theorized components of sensory processing described by Ayres (1972). It includes: (1) registration or paying too little attention or overreacting to sensory stimuli; (2) modulating the incoming stimuli; and (3) integration of sensations, which influences the body percept and is a foundation of motor planning (Ayres, 1979).

Wilbarger and Wilbarger (1991) have estimated that as much as 15% of the population may experience some level of sensory defensiveness. They define sensory defensiveness as:

a tendency to react negatively or with alarm to sensory input that is generally considered harmless or non-irritating. Common symptoms include oversensitivity to touch, sudden movement, or over reaction to unstable surfaces, high frequency noises, excesses of noise or visual stimuli and certain smells. (p.3)

Sensory defensiveness and other sensory processing and modulation disorders have been studied in children (Cermak and Daunhauer, 1997; DiGangi and Brienbauer, 1997; Dunn, 1997) but have not been explored widely in adults. The effect of sensory defensiveness in adults, as described by Oliver (1990), may be that a person's routine decisions may be 'ruled' by perceptions of the sensory experience they will engender, including choice of clothing, where they go and with whom they relate.

Kinnealey, Oliver and Wilbarger (1995) described the subjective experience of five sensory-defensive adults. The adults vividly described how sensory defensiveness affected their roles and occupational performance, as well as whether or not or how they engaged in daily routines. The adults also described the emotional and cognitive energy which was required as well as the time-consuming strategies they employed to cope with the discomfort of being sensory defensive. Kinnealey et al. (1995) proposed a conceptual framework for studying sensory defensiveness in adults which included investigating: (1) its causes; (2) the physical, social and emotional sequelae of defensiveness; and (3) the effectiveness of intervention strategies.

The emotional and behavioural aspects of sensory defensiveness were first described by Ayres (1961, 1964, 1972, 1979) in their relationship to tactile defensiveness, which Ayres saw as part of a set of nervous-system responses to auditory, olfactory and visual stimuli (Ayres, 1972). She described behaviours of hyperactivity and distractibility in some children and noted that anxiety surrounded all tactile experiences that were not self-initiated. Ayres suggested that there was an interaction between anxiety and somatic afferent imbalance that was self-perpetuating. That is, anxiety may be both a causative and a resultant factor of the somatic or afferent imbalance which leads to emotional lability (Ayres, 1961). Ayres (1964) also noted that control and perception of control influence the response of the defensive person to various stimuli.

Consequently, there is an increased negative response when the stimuli are unexpected.

The defensive responses described by Ayres in the tactile system (Ayres, 1964, 1972) and the vestibular system (1979) were postulated to occur in all of the sensory systems (Knickerbocker, 1980; Royeen and Lane, 1991; Wilbarger and Wilbarger, 1991). Like Ayres, the Wilbargers (1991) described the behavioural and emotional effects of sensory defensiveness and how defensive reactions involving primitive survival and arousal mechanisms, related to the limbic system, have a potentially negative effect on every aspect of a person's life. The term `sensory affective disorder' was used by Wilbarger and Wilbar er (1991) to describe this situation.

Royeen and Lane (1991) further described the relationship between sensory modulation disorders such as sensory defensiveness and the limbic system, specifying its relationship to hyper-emotionality, exaggerated defence mechanisms, increased levels of activity, sleep disturbance and failure to persist in new tasks. Anxiety, stress, unfounded apprehension and fear are associated with the limbic structures and components of the reticular system, hypothalamus and cortex, as well as the neurotransmitters that are associated with this region (Ashton, 1987; Royeen and Lane, 1991).

Anxiety is considered normal when it is in response to a 'realistic' threat and dissipates when the danger is no longer present (Beck and Emery, 1985). A certain level of anxiety motivates individuals to participate in life and complete tasks. However, anxiety can also be debilitating and paralysing (Beck and Emery, 1985). Vulnerability is believed to be at the core of anxiety disorders, that is, if a person perceives himself or herself as being subject to dangers beyond his or her control (Clark et al., 1994).

According to DesLauriers (1995), anxiety disorders are the most common psychiatric illness in the United States. There is a wide range of symptoms and severity. In many cases anxiety is not diagnosed, but the individual seeks treatment for somatic complaints. The cause of anxiety is currently believed to be a combination of biological vulnerability and psychological stressors (DesLauriers, 1995). More specifically, Rosenbaum and colleagues (1995) suggest an approach to treating anxiety disorders which considers anxiety as a consequence of constitutional vulnerability shaped by developmental experiences and activated by environmental experiences.

Generalized anxiety is characterized as free-floating anxiety due to unidentifiable stressors and somatic complaints. There is a 90% comorbidity rate in people diagnosed with anxiety, with depression being the most common diagnosis (American Psychiatric Association, 1994; Kaplan et al., 1994; Hollifield et al., 1997; Sussman, 1997). Many shared symptoms are found in generalized anxiety and anxiety depressive disorder, including difficulty concentrating, sleep disturbance, low energy and irritability. An additional symptom of anxiety is being `on edge', compared with hypervigilance in anxiety/depressive disorder (American Psychiatric Association, 1994; Kaplan et al., 1994). Depression and anxiety have been linked to somatic complaints and, in a number of cases, pain has been suggested as a symptom in both (Beutler et al., 1988; Castrogiovanni et al., 1989).

Sensory defensiveness, anxiety, depression and pain perception share a number of behavioural and physiological traits. Hypervigilance and increased levels of arousal, including increased sympathetic nervous system activity, are signs observed both in individuals experiencing pain (Melzack and Wall, 1973) and in individuals with anxiety disorders (Last and Hersen, 1988). Also, control or the perception of control is a factor mediating pain (Melzack and Wall, 1973), anxiety (Kutash, 1980) and depression (Seligman, 1975).

All four conditions are influenced by perception of sensory/somatic stimuli, result in increased attention to and increased reactivity to sensory/somatic stimuli, have similar sympathetic nervous system responses to stimuli, and employ control, control/avoidance and other affective responses. Given that the literature supports the relationship of these conditions, it could be deduced that adults who are sensory defensive would also report increased anxiety, depression and somatic complaints or pain perception. Therefore, the purpose of this study was to explore possible sequelae of sensory defensiveness in adults by investigating the relationship between sensory defensiveness and anxiety, depression and pain perception in adults. To explore the nature of the phenomenon it was important to control for confounding variables such as diagnosis or history which might have condition-related symptoms. Therefore, normal functioning adults were recruited for this study.

Method Participants

The participants consisted of volunteer adults, recruited through word of mouth from a variety of work and social contacts of the investigators. No person approached declined to take part in the study. To rule out variables which might confound the exploration of sensory defensiveness, participants who reported a history of physical or sexual abuse, or a diagnosis of psychopathology, were excluded. One person was excluded because of a mental health diagnosis, one because of a history of physical abuse, and two as a result of a history of sexual abuse. Participants were screened, using the Forty-eight Item Counseling Evaluation (McMahon, 1976), in order to exclude participants with unidentified psychopathology. No potential participant was excluded from the study based on the results of this screening, as all met the criterion of no unidentified psychopathology, that is, scoring 20 or above. All participants reported little or no familiarity with the concept of sensory defensiveness.

Group assignment was based on two criteria. The first criterion was the score on the ADULT-SI (Kinnealey et al., 1994). Scores of more than 25 suggest sensory defensiveness and scores of less than 25 suggest mild or no defensiveness. All participants identified as having sensory defensiveness scored above 28 and all non-defensive adults scored below 24.

The ADULT-SI, an assessment based on an interview to identify and describe sensory defensiveness in adults, was in the process of being developed. Therefore, the second criterion was that scoring to determine sensory defensive, non-sensory defensive and group assignment was corroborated by a second rater, who independently listened to and scored the audiotaped interviews and recommended group assignment. There was 100% agreement between raters on which participants had sensory defensiveness and which did not, as well as on group assignment.

Each group consisted of 16 subjects: 12 female and 4 male; 2 African American, and 14 Caucasian. Their ages, as shown in Table 1, ranged from 21 to 48 with a mean age of 32.9. The mean age of the sensory-defensive group was 32.6, +6.7. The mean age of the non-sensory-defensive group was 33, +7.9.

Fifteen participants who were sensory defensive were recruited through word of mouth among occupational therapists. The study was approved by the Institutional Review Board for the use of human subjects of the university. For the participants' comfort, the researcher met with them in the setting of their choice, most often in their homes. Consent to participate in the study and to audiotape the ADULT-SI for reliability purposes was obtained. Participants were administered the ADULT-SI to determine if they had sensory defensiveness. They were screened using the Forty-eight Item Counseling Evaluation and asked whether they had a history of physical or sexual abuse or a mental health diagnosis. If they had a history of abuse, a mental health diagnosis, or scored more than 20 on the screening, they were excluded from the study. Fifteen persons were sought. Because one participant refused to give her age, a 16th person was recruited. The IPAT Anxiety Scale, the IPAT Depression Scale and the Pain Apperception Test were then completed by the participants.

Next, a non-sensory-defensive control group was recruited and participated in the same procedure as the sensory-defensive group. Participants in the control group continued to be recruited until there was a group which matched the sample in age, gender and race. A 16th person was recruited who seemed the same age as the participant who refused to provide her age (otherwise matched for gender and race) and was included in the control group.

Instrumentation

Since the study was a pilot exploratory study using volunteers, instruments were sought which were noninvasive, brief, reflected the participants' perspective and did not require professional interpretation of scores. Instruments were required which were standardized, and available through a test publishing company with manuals reporting reliability, validity and standardization data. There are no published tests for identifying sensory defensiveness in adults, which is usually accomplished through clinical judgement of an occupational therapist. Therefore, the pilot edition of the ADULT-SI was used, supplemented by independent clinical judgement of two occupational therapists.

In order to exclude participants with psychopathology, the Forty-eight Item Counseling Evaluation Test (McMahon, 1976) was administered. This self-administered, true/false questionnaire was designed to increase accuracy in identifying personal and emotional problems of adolescents and adults. The Forty-eight Item Counseling Evaluation manual (McMahon, 1976) reports the following reliability and validity: reliability in three consecutive studies is reported as 0.80, 0.82 and 0.88. A number of validity studies are reported in the manual, with agreement of 0.92 between counsellor evaluation and the results of the Forty-eight Item Counseling Evaluation (McMahon, 1976).

Scores can range from 0 to 48, with higher scores indicating a higher degree of maladjustment or psychopathology. Scores of more than 20 indicate that clinical attention is warranted. No participant in this study scored 20 or above.

The ADULT-SI (Kinnealey et al., 1994) is a tool for identification and assessment of sensory defensiveness in adults. The determination of sensory defensiveness has traditionally been accomplished through clinical judgement by the occupational therapist. Although several tools have been, or are in the process of being, developed for children (Royeen and Fortune, 1990; Dunn and Brown, 1997; Dunn and Westman, 1997), none of these is designed for adults. A pilot edition of the ADULT-SI was used for this study and additional reliability and validity studies have been completed since that time.

The ADULT-SI is an 84-question tool with a semi-structured, openended interview format. The questions are designed to elicit descriptive responses which are judged by the therapist as defensive (scored as 1) or non-defensive (scored as 0). Scores can range from 0 to 84. Scores of less than 25 indicate no or mild defensiveness, whereas scores of more than 25 indicate defensiveness.

Since the ADULT-SI relies on the clinical judgement of the occupational therapist for scoring, which in turn was the basis for group assignment, a second independent rater scored the audiotaped interviews of the participants. There was 100% concurrence between the two raters in identification of sensory defensiveness and on group assignment. Present reliability of the ADULT-SI reported in the ADULT-SI manual (Kinnealey and Oliver, 1999) is as follows: co-coding transcripts, 0.90; identification of sensorydefensive/non-sensory-defensive adults based on interview, 1.00; and clinical decision summary based on ADULT-SI scores, 0.88.

Procedure

The presence of anxiety was measured using the IPAT (Institute for Personality and Ability Testing) Anxiety Scale (Cattell and Scheier, 1976). This 40-item paper-and-pencil questionnaire has reliability coefficients ranging from 0.80 to 0.93. Its validity is reported to approach 0.90 (Cattell and Scheier, 1976). Raw scores range from 0 to 80 and can be transformed into standard scores. However, the raw scores were used for this study.

The presence of depression was measured using the IPAT Depression Scale (Krug and Laughlin, 1976), a 40-item paper-and-pencil questionnaire based on factor-analytic studies of depression. The authors report validity of 0.88 and internal consistency of 0.93. Raw scores can be transformed into standard scores. For this study, raw scores were used.

The presence of somatic complaints was measured using the Pain Apperception Test (Petrovich, 1973), a projective instrument which focuses on the emotional aspects of pain. Participants judged the intensity and duration of pain felt by individuals depicted in a picture. The authors report a high degree of face validity. Split-half reliability coefficients for pain duration range from 0.56 to 0.84 and, for pain intensity, from 0.66 to 0.89, depending on the population tested.

Results

The Forty-eight Item Counseling Evaluation was originally designed to aid counsellors from various fields in identifying personal and emotional problems in adolescents and adults. For the purpose of this study, the Forty-eight Item Counseling Evaluation was administered to screen out participants who had clinical disorders. The test is constructed so that a higher numerical score indicates a higher degree of maladjustment or psychopathology. Scores above 20 indicate that clinical attention is warranted. No participants recruited for the study scored above 20. Although no research question was advanced related to the results of this test, a t-test comparing the mean scores of the two groups was calculated (see Table 2).

As shown in Table 2, a two-tailed t-test indicated that there was a difference significant at the 0.005 level between the sensory-defensive and non-sensory-defensive groups, with the sensory-defensive group demonstrating increased levels of maladjustment.

TABLE 2:

Question 1. Is there a difference between sensory-defensive (SD) and nonsensory-defensive (NSD) adults in levels of anxiety as tested by the IPAT Anxiety Scale? A t-test was calculated on the group mean.

As shown in Table 3, there was a difference in group means on the IPAT Anxiety Scale at the 0.05 level of significance, indicating that the sensory-defensive group experienced higher levels of anxiety than did the non-sensory-defensive group.

Question 2. Is there a difference between SD and NSD adults in depression as tested by the IPAT Depression Scale? A t-test was calculated between group means. The IPAT Depression Scale was constructed to yield two scores - one of which was corrected for anxiety. This was the score that was used to calculate the mean for the purposes of this study.

As shown in Table 4, there was a difference at the 0.05 level of significance between the two groups in terms of reported levels of depression, with the sensory-defensive group exhibiting higher levels of depression.

Question 3. Is there a difference between the SD and NSD groups in perception of pain as tested by the Pain Apperception Test? A t-test was calculated between the mean group scores. As shown in Table 5, no difference was found between groups in the perception of pain as tested by the Pain Apperception Test.

Discussion

The findings of increased scores on the tests in symptoms of maladjustment, anxiety and depression in the sensory-defensive participants support clinical impressions of this relationship. The mean difference between groups in anxiety and depression, while significant at 0.05, could be considered weak and should be interpreted with caution. Severe sensory defensiveness, according to Wilbarger and Wilbarger (1991), is usually found in conjunction with other diagnoses. This study excluded participants with a diagnosis, thereby possibly excluding participants with severe sensory defensiveness. In spite of this, a difference was found between the groups in increased symptoms of anxiety and depression. If anxiety and depression are associated with sensory defensiveness, then further study into the nature of the interaction is recommended. Anxiety has long been clinically associated with sensory defensiveness in children and is supported in this study with adults.

Conversely, sensory defensiveness may be an unrecognized contributing or confounding factor in some people with anxiety.

TABLE 3:

The findings of increased symptoms of depression in the sensory-defensive group also requires exploration into possible deleterious interactions. Defensive reactions to sensory stimuli frequently result in social and physical withdrawal, isolation and decreased sensation seeking (Oliver, 1990; Kinnealey et al., 1995), all of which could conceivably contribute to depression. Social or physical isolation and reduced sensory stimulation, whether exacerbated by depression or by sensory defensiveness, may have deleterious effects on many aspects of functioning. In persons identified with sensory defensiveness, possible coexisting depressive symptoms may need to be identified and addressed.

Although the literature linked sensory defensiveness and pain perception, results of this study did not support this relationship. Responses were based on the participants' projection of perception of pain when viewing pictures. Some participants verbalized confusion in interpreting the pictures. Although the participants might recognize their own low pain tolerance, they may answer questions in a way they believed most people would respond. This question requires further investigation.

Results of this research support the clinical impressions described by Oliver (1990), Wilbarger and Wilbarger and Wilbarger (1991) and Kinnealey et at. (1995), that social and emotional problems are found in conjunction with sensory defensiveness in adults. Wilbarger and Wilbarger (1991) further theorize that sensory defensiveness can result in social and emotional issues that can impact many aspects of a person's life, resulting in a `sensory affective disorder'. Further research, however, is required to support a causal relationship.

TABLE 4: TABLE 5:

Application of the results of one pilot study to treatment is premature. However, the identification of the presence of sensory defensiveness in adults referred for occupational therapy intervention and knowledge of its sequelae could lead to the choice of more efficient and effective intervention strategies by occupational therapists. One approach might be the incorporation of a sensory diet into the treatment programmes or lifestyles of the patients (Wilbarger, 1995).

Limitations of this study include the small size and non-random selection of voluntary participants. The results, therefore, cannot be generalized. A second limitation is the instrument used to identify participants with sensory defensiveness. Traditionally, sensory defensiveness has been determined through clinical judgement of an occupational therapist, based on behaviour described or observed. For this study a pilot edition of the ADULT-SI was used. It is a tool designed to identify and assess sensory defensiveness in adults. Two raters independently scored the interviews from audiotapes and judged whether a person was sensory defensive. There was 100% agreement between raters on whether a person was or was not sensory defensive. Reliability and validity studies of the tool have since been completed.

Conclusion

In conclusion, sensory-defensive adults with no history of physical or sexual abuse, or psychological diagnosis, were compared with a matched group of non-sensory-defensive adults in an exploratory pilot study. The sensory-defensive adults demonstrated increased scores on anxiety, depression and maladaptation compared with the non-defensive group. They did not differ in pain perception as tested in this study. The study supports literature which suggests that there are increased social and emotional issues in persons with sensory defensiveness. It also supports literature suggesting a relationship between sensory defensiveness and anxiety. Further research is required to explore this relationship as well as the nature and implications of the sensory emotional link in adults. Research is also recommended into the impact of sensory defensiveness and its sequelae on the performance of life roles, occupational performance and life satisfaction.

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