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Specific Phobias |
Overcoming Anxiety (Home) > Specific Phobias > Developmental Aspects Specific Phobia Developmental Aspects and TreatmentOne robust finding in clinical studies is that, in general, specific phobias are characterised by early onset ages. For example,O ¨ st found mean onset ages of 7 and 9 years for animal and blood-injury-injection phobias, respectively. An early onset is also found in natural environment phobias. Thus, a considerable percentage of height fearful subjects report that their fear has always been present . It should be noted, though, that situational fears such as claustro- phobia differ from this pattern in that they have a later onset. Thus, O ¨ st reports a mean onset age of 20 years for his sample of claustrophobics. This late onset accords with the impression that claustrophobia is a more ‘‘sophisticated’’ fear, at least when one looks at the sort of cognitions that are involved. Nevertheless, generally, a substantial proportion of specific phobias begins in childhood. This finding is underlined by surveys of subclinical fears among children. In an early study by MacFarlane et al. it was found that only a small minority of a large sample of children (N= 1096) displayed no fear reactions. Lapouse and Monk reported a similar finding. In a more recent study, Muris and colleagues found that specific fears are common among four- to six-year-old children (71%), peak between ages seven to nine (87%), and then decline in 10 to 12 year olds (68%). Together, these and other studies demonstrate that mild to moderate fears are quite normal phenomena in childhood. In this connection, there are several points that deserve comment. First, studies that are evaluating specific fears in children, have consistently found that girls report more fears than boys. Second, the mild fears seen in children often represent transient developmental phenomena. That is to say, childhood fears follow a predictable course. Bauer found that fear of ghosts and fear of animals are common in children aged four to eight. In contrast, fear of injury is more often found in children aged 10 to 12. According to Bauer, these fluctuations in childhood fear are closely tied to cognitive development. Younger children would rely on global perception and animistic concepts in interpreting cause–effect relationships. This would explain why their fears are directed at ghosts and animals. Bauer’s emphasis on cognitive development makes sense. For example, the visual cliff phenomenon (i.e., fear of heights) that typically occurs in young babies between four and nine months has long been interpreted as a prototype of a genetically based fear. Yet, experiments show that this phenomenon critically depends on locomotion development in infants. Third, while it is clear that the majority of childhood fears disappear spontaneously, there are also indications that in a subgroup of children, specific fears persist and tend to radicalise. Thus, the critical question is why, in some cases, specific fears appear to continue from childhood into adulthood. There are good reasons to believe that genetically based temperamental traits play an important role in this context. Germane to this issue are studies on behavioural inhibition . Behavioural inhibition refers to the tendency of some children to interrupt ongoing behaviour and react with vocal restraint and withdrawal when confronted with unfamiliar people or settings. Behavioural inhibition is thought to be a stable and inherited trait that characterises approximately 10% to 15% of children. Cross-sectional and longitudinal data collected by Biederman and co-workers strongly suggest that this trait constitutes a risk factor for anxiety disorders. More specifically, these authors noted that compared to control children, pre-school children identified as behaviourally inhibited are more likely to have anxiety disorders (including specific phobias). This became even more prominent at a three-year follow-up. That is, in the cohort of children who were initially identified as behaviourally inhibited, the rates of specific phobias and other anxiety disorders had increased markedly. Thus, behavioural inhibition seems to be a vulnerability factor for a broad range of anxiety disorders, among which are specific phobias. It is not surprising, therefore, that this trait has been linked to other higher-order constructs such as neuroticism, trait anxiety , and negative affectivity . Recent studies have sought to elucidate the neurobiological underpinnings of these higher-order traits. According to some authors, hyperexcitability in the amygdala is associated with behavioural inhibition. This hyperexcitability would promote a development from normal, adaptive fear states into pathological anxiety. Other authors have found that response styles such as behavioural inhibition are subserved by hyperactivity in the right frontal areas, a finding that accords well with the hypothesis that the anterior cortex is involved in avoidance behaviour. The precise biological parameters of behavioural inhibition await further clarification. Meanwhile, it should be stressed that about 70% of the children classified as behaviourally inhibited remain free of any anxiety disorder. Apparently, then, learning experiences determine whether genetically transmitted vulnerabilities culminate in specific phobias.
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