The close interaction between emotion and cognition was suggested by behavioural and neuroimaging studies from both healthy and mentally ill individuals (e.g. Beck et al. Reference Beck, Rush, Shaw and Emery1979, Reference Beck, Emery and Greenberg1985; Isen et al. Reference Isen, Daubman and Nowicki1987; Williams et al. Reference Williams, Watts, MacLeod and Mathews1997; Bush et al. Reference Bush, Luu and Posner2000).
Cognitive processing of emotional material appears to be affected by pathology-coherent biases in individuals with emotional disorders (Beck et al. Reference Beck, Rush, Shaw and Emery1979, Reference Beck, Emery and Greenberg1985; Bellani et al. Reference Bellani, Moretti, Perlini and Brambilla2011). Studies indicated that clinically depressed adults are keener on remembering negative/sad rather than positive material (e.g. Bradley et al. Reference Bradley, Mogg and Williams1995), whereas anxious people show an attentional bias towards threatening stimuli (MacLeod et al. Reference MacLeod, Mathews and Tata1986). In addition, this bias seems to affect specific cognitive functions, but not others, in different psychiatric disorders. For instance, MacLeod et al. (Reference MacLeod, Mathews and Tata1986) tested general anxiety disorder (GAD) and depressed adults with an emotional dot-probe detection task. The task consisted in detecting a dot that could appear in the same or different location as either an emotional threat-related or neutral word. They showed an attentional bias towards threat-related stimuli, if compared with the neutral condition, only in GAD (i.e. faster detection when the dot appeared in the same location as the threat-related word). The depressed patients, instead, attended equally to the emotional and neutral words (MacLeod et al. Reference MacLeod, Mathews and Tata1986). A lack of effect of negative emotional stimuli in depressed adults was confirmed in another study that used the same dot-probe detection task, but presented depression-related, instead of threat-related words (Gotlib et al. Reference Gotlib, McLachlan and Katz1988). Conversely, an emotional symptom-congruent bias was found only in clinically depressed but not in GAD adults by Bradley et al. (Reference Bradley, Mogg and Williams1995). They showed that depressed patients freely recalled more depression-relevant than anxiety-relevant or neutral word and were faster in a lexical decision task when they had to answer to previously primed depression-relevant words.
Neuroimaging investigations in healthy volunteers suggested a parcellation of the anterior cingulate cortex (ACC) into a cognitive and emotional part that interacts through a mechanism of reciprocal suppression. In particular, cognitive demanding tasks activate the cognitive ACC part as well as a deactivation of the emotional ACC part. Conversely, emotional stimulation leads to activation of the emotional ACC and deactivation of the cognitive ACC part (see Bush et al. Reference Bush, Luu and Posner2000 for review). In addition, a reduced activation in left ventral prefrontal cortex (PFC) was found in adults with bipolar disorder (BD) when performing an emotional-modified Stroop colour-naming task – requiring to say the colour on which a word was written while ignoring the word itself – if compared with controls (Malhi et al. Reference Malhi, Lagopoulos, Sachdev, Ivanovski and Shnier2005).
A pattern of cognitive biases similar to the one found in adults was revealed in children with emotional disorders. For instance, clinically depressed children recalled significantly more negative (e.g. sad) adjectives than (e.g. happy) positive, whereas the controls had comparable performances with both. Interestingly, this tendency became stronger with age in the depressed group. In addition, the same study did not find any difference between the depressed and the control groups in a recognition task (Neshat-Doost et al. Reference Neshat-Doost, Taghavi, Moradi, Yule and Dalgleish1998). This suggested that, similarly to adults, in paediatric depression the bias is specific to one cognitive domain, as it acts only on free later recall and not on delayed recognition of previously presented emotional material.
This result (i.e. symptom-congruent memory bias) was not replicated in a study that tested children and adolescents with depression, GAD or post traumatic stress disorder (PTSD) (Dalgleish et al. Reference Dalgleish, Taghavi, Neshat-Doost, Moradi, Canterbury and Yule2003), probably because other-referent words (e.g. sadness) and not self-referent adjectives (e.g. sad) were used. Beside memory, Dalgleish et al. (Reference Dalgleish, Taghavi, Neshat-Doost, Moradi, Canterbury and Yule2003) highlighted an attention bias towards threatening stimuli specific to the anxious group (GAD and PTSD combined together), with anxious detecting faster the dot-probe when presented in the same location as a threat related word (e.g. horror). However, only the GAD showed a bias towards threat-related words, whereas PTSD had a bias away from depression-related words (i.e. they were slower in detecting the dot-probe when it appeared in the same location as the depression related word). Depressed and control children did not show any symptom-congruent attentional bias and no group reported any effect in the modified Stroop task. These results are consistent with previous investigations in both adults (Beck et al. Reference Beck, Rush, Shaw and Emery1979, Reference Beck, Emery and Greenberg1985; also see Williams et al. Reference Williams, Watts, MacLeod and Mathews1997 for a review) and children (Taghavi et al. Reference Taghavi, Neshat-Doost, Moradi, Yule and Dalgleish1999; Bot et al. Reference Bot, de Leeuw den Bouter and Adriaanse2011) and favour the hypothesis that a symptom-congruent bias on attention is specific to anxiety disorder.
An attention bias towards words expressing social-treat and manic/irritable mood was reported on a sample of children of BD parents on an emotional Stroop task administered after negative mood induction (Gotlib et al. Reference Gotlib, Traill, Montoya, Joormann and Chang2005). Also, in a functional magnetic resonance imaging (fMRI) study, negative words, relative to the neutral, elicited greater activation in the ACC and left amygdala and less activation in right rostral ventrolateral PFC and dorsolateral PFC in BD children. This favours the hypothesis that in paediatric BD there is both an enhanced reactivity in the limbic system and a reduced capacity of regulating this response by PFC when negative emotional stimuli are presented. The same pattern of activation was not found in paediatric BD for the positive words and it was not present for the healthy controls, neither in the positive condition nor in the negative condition (Pavuluri et al. Reference Pavuluri, O'Connor, Harral and Sweeney2008).
In summary (Table 1), cognitive functions seem to be biased in paediatric psychopathology in a way that mirrors the pattern of biases previously found in adults. The bias was revealed to be symptom-coherent and the cognitive functions involved appear to depend on the specific disorder that is taken into account. Moreover, the same neural substrates that proved to process or regulate emotional states in adults were found to have an atypical pattern of activation in children with anxiety disorders or BD. Indeed, the biases on cognitive functions are established in the early life, supported by an unusual development in some aspects of the neural substrates functionality, and more specifically in the ACC, in the limbic system and in the PFC, and are maintained throughout adulthood.
Table 1. Summary of the results
ACC, anterior cingulate cortex; BP, bipolar disorder; GAD, general anxiety disorder; PBD, paediatric bipolar disorder; PFC, prefrontal cortex; PTSD, post traumatic stress disorder; fMRI, functional magnetic resonance; vPFC, ventral prefrontal cortex.
More research is needed to better define which cognitive functions suffer from emotional biases in different disorders, as well as the mechanisms through which those biases act. Moreover, despite the wide use of emotional linguistic stimuli in research on psychopathology, to date no studies investigated the development of the emotional as compared with neutral word lexicon in children with emotional disorders. Hence, we suggest that investigations on emotional language should be carried out to have clearer pictures of each psychopathology and to plan effective therapeutic strategies.
