Although dental phobia afflicts men and women, gender differences in neural correlates of this disorder have not been investigated thus far. We recorded event-related potential (ERPs) in 30 individuals with dental phobia (15 women, 15 men with comparable disorder severity) and 30 nonphobic controls (15 women, 15 men) while they passively viewed pictures depicting dental treatment, generally fear-eliciting, disgust-eliciting and neutral contents.
Male and female individuals with dental phobia as compared with controls displayed an enlarged centro-parietal late positivity (300–1500 ms). Gender difference concerned prefrontal ERPs. Only men with dentophobia showed an enhanced positivity towards the phobic relative to the neutral pictures in the time window between 300 and 1500 ms. Such a differentiation was absent in the other groups (male controls, female phobics, female controls). This finding indicates a gender-dependent recruitment of frontal attention networks in dental phobia and might reflect that male and female sufferers of dentophobia differ with regard to controlled attention focusing and cognitive avoidance during exposure.
Dental phobia is a common type of specific phobia, which affects approximately 2–4% of the general population (e.g. Oosterink et al., 2009). The disorder is characterized by extreme and uncontrollable fear of dentistry and pronounced avoidance of seeking dental care. In terms of dental health and overall well-being, the symptoms can have serious ramifications (Armfield, 2008).
Dental phobia has a less skewed gender distribution than other types of specific phobia; e.g. Oosterink et al. (2009) reported a prevalence of 4.6% in females compared to 2.7% in males. Despite the considerable amount of male and female individuals afflicted by this disorder, gender differences in dental-phobic symptoms and associated problems have hardly been investigated. One exception is a study by Sartory et al. (2006) who demonstrated that female and male individuals with dental phobia were comparable in many clinical features (e.g. dental pain, negative emotions related to dental treatment), but differed in the displayed avoidance behavior and the perceived internal control during the treatment.
The majority of studies on gender effects focused on dental fear instead of phobia. Several studies (e.g. Eli et al., 2000 and Heft et al., 2007) found that men reported lower levels of dental anxiety than women, although they expected more pain. After the completion of the treatment, women remembered more pain and other negative experiences (Eli et al., 2000 and Locker et al., 1996). In contrast, Settineri et al. (2005) observed no gender differences in global dental anxiety; only specific fears in relation to the use of dental instruments and the tilted-back position of the chair differed between the two groups. Such gender effects might be a result of a lower perceived capability of control in women relative to men afflicted with dental fears (Liddell and Locker, 1997).
Besides little knowledge about gender differences in dental phobia, the neuronal basis of this disorder is also poorly understood. There is only one published study on electrocortical correlates of dental phobia during symptom provocation (Leutgeb et al., 2011). This investigation with exclusively female participants observed that phobics relative to controls showed an enhanced late positivity (300–700 ms) when confronted with pictures displaying dental treatment. This enhancement was most pronounced across parietal electrode sites and was interpreted to reflect motivated attention. Similar ERP effects have been reported in numerous studies on animal phobias (e.g. Leutgeb et al., 2009, Michalowski et al., 2009, Miltner et al., 2005, Muehlberger et al., 2006 and Schienle et al., 2008). The observed increased parietal late positivity in phobic patients was understood as an indicator of automatic allocation of attentional resources towards the phobic object.
Late positivity changes in spider phobics were observed in a study on exposure therapy by Leutgeb et al. (2009). After successful treatment the patients displayed a fronto-central LPP enhancement as compared with the LPP before therapy. This treatment effect was discussed in terms of reduced attentional avoidance and increased control experience.
Interestingly, ERP findings on blood-injection-injury (BII) phobia are less clear. Buodo et al. (2006) found that blood phobics and controls responded to mutilation pictures with comparable parietal P300 and LPP amplitudes, suggesting that blood phobics did not assign enhanced attentional resources to the phobic stimulus. In a subsequent study of the group (Buodo et al., 2010) participants were simultaneously presented with disorder-relevant and-irrelevant pictures. BII phobics displayed an increased N2pc which is an indicator of an early visuospatial attentional bias. Finally, in a study by Sarlo et al. (2011) blood phobics displayed an enlarged N100 and a reduced parietal and central LPP (600–800 ms) towards mutilation pictures relative to controls. This pattern might reflect a processing bias involving early selective encoding and late cognitive avoidance. As in all previous investigations, only females were studied.
The main objective of the present investigation was therefore to compare affective and ERP responses (N100, N200, P100, P300 and LPP) between males and females suffering from dentophobia when exposed to disorder-relevant material. Based on previous findings (Sartory et al., 2006, Liddell and Locker, 1997, Leutgeb et al., 2009 and Sarlo et al., 2011) we expected that relative to male phobics female phobics would display a reduced fronto-central late positivity during symptom provocation as they experience less cognitive control and show more avoidance behavior.
