Background:
Body dysmorphic disorder (BDD) is characterized by an overvalued or delusional belief of ‘imagined ugliness’. According to the literature, delusional beliefs have been explained by four alternative theories, which include faulty perceptions, theory of mind deficits, reasoning abnormalities and corruption of semantic memory. The current study examined whether these potential explanations are relevant to delusion formation in BDD.
Method:
Preliminary data from 10 BDD patients and 10 matched healthy controls were analyzed. The clinical assessment involved questionnaires measuring self-esteem, self-ambivalence, delusional thinking and creative experiences. The cognitive test battery included visual affect perception, semantic memory for somatic concepts, cognitive inhibition associated with somatic and nonsomatic words, and language fluency.
Results:
The results confirmed previous findings that patients with BDD are more delusional but additionally showed that delusional beliefs are exceedingly distressing and preoccupying for these patients. Similarly, on a semantic memory task, patients with BDD showed greater acceptance of unusual ideas especially with regard to somatic compared with neutral information. On the fluency task, patients with BDD showed impaired semantic fluency but intact phonological fluency. Furthermore, patients with BDD were impaired in recognizing angry facial expressions, with no deficits on identifying other emotions.
Conclusions:
These results have indicated the influence of delusional thinking on cognitive processing in BDD. They have suggested that delusional beliefs may be explained in terms of impaired semantic memory and faulty perception of angry information; these deficits in turn may explain the specificity of preoccupations in BDD.
