Norma NMX-SAST-26000-IMNC-2011 GUIA DE RESPONSABILIDAD SOCIAL

1.8.5.1. Clinical features

TBl patients tiave been described as having an impaired capacity for social perspectiveness, reflected in self-centred bWiaviour and limited ability to empathise and self-reflect (Lezak, 1978A). More recently, Lezak (1995) noted diat reduced self-awareness and empathy particularly following moderate and severe TBl has n ^ativ e consequences for social fimctioning.

1 diall now consider the role o f dieoiy o f mind impairment in contributing to these rqxirted problems.

1.8.5.2. Defining theory o f mind

Theory o f mind has bear defined as the ability to recognise and comprdiend odier people's mental states (e.g. Baron-Cohen, 1985). It should be noted that theory o f mind appears to be similar to the concqit o f empadty, aldiough Restak (1984) notes tiiat various definitions and measurement approaches has limited a clear understanding o f this concept. This is complicated further by the fact that diere appears to be vary litde discussion in the autism or TBl literature about the relationship between theory o f mind and empadiy. It would appear that two aspects

o f empathy have been considered in tihe literature. The first is cognitively based empathy (which is associated with paspective taking) and the second is affectively based empathy (which involves vicarious arousal). Thus, the concept o f cognitive empathy is reasonably consistent with dieory o f mind. Bodi these concepts will be the focus o f the following discussion. The concept o f affective empathy has been given very litde explicit consideration following TBl but appears to overlap with the literature on emotional deficits considered later.

1.8.5.3. Models and neuroanatomical correlates

The concept o f theory o f mind has largety been associated widi understanding the interpersonal and social deficits observed in in&ntile autism (e.g. Baron-Cohm, 1985). It has been argued diat theory o f mind is an important 6ctor in the normal development o f social, communicative and imaginative abilities. There have been two levels o f theory o f mind described. First order belief attributions refer to the ability to think about anodier person s thoughts about an objective event Second (or higher) order belief attributions refer to the ability to think about anodic person s thoughts about a third person’s thoughts about an objective evmt.

Brain imaging studies in healthy controls suggest a link between dieory o f mind and die fiontal lobes, aldiough Charmon and Crawford (2000) note that specific brain areas identified have varied according to die task used and finther understanding is required. The left fiontal lobe has been implicated (Fletcher et al, 1995; Goel et al, 1995) in addition to the right orbitofiontal r ^ o n (Baron-Cohen et al, 1994). In addition, Baron-Cohen et al (1999) speculated about the role o f the left amygdala in social processing.

Very few brain lesion studies exist exploring the role o f the frontal lobe in dieory o f mind. There is some evidence to suggest that patients widi lesions involving die fiontal lobe have

difficulty paibrm iug tasks tag? higher-level dieoiy-of-mind-type social comprehension (e.g. McDonald and Pearce, 1996; Bara et al, 1997; Channon and Crawford, 2000). (These studies will be reviewed in chs^tear three). However, some studies also implicate impaired ability in lesions to the right honiq)here (e g. see Happé et al, 1999; Bronwell et al, 1990; Winnor et al, 1998).

Channon and Crawford (2000) note that diere is disagreement about the contributions o f the fixmtal lobe and right hemisphere. McDonald (1993a) argues diat it is important not to ignore die possibility that impairment in dieory o f mind tasks in right hemisphere studies could be attributable to frontal lobe impairment due to diffiise lesions often observed in patients. A recent s tu ^ by Channon and Crawford (2000) showed that patients with left anterior lesions performed significantly more poorty on a higher-level theory-of-mind-type story comprehension task, compared to patients with right anterior and posterior lesions. Th^r argued this finding was consistent with brain imaging studies unplicatmg die involvement o f the left frontal lobe in theory o f mind.

Although there is evidence to suggest that theory o f mind is linked to the fiontal lobes, dûs brain area is also associated with executive fimctiorL Therefore, dûs raises the issue o f die relationship between theory o f mind and executive function.

1.8.5.3.1. Theory o f mind and executive fimction

There is debate in the autism literature about the relationship b^ween theory o f mind and executive fimction and the d ^ re e to which these constructs are separable processes (e.g. Bishop, 1993). It has been argued diat theory o f mind and executive fimction deficits arise as a result o f damage to areas o f die prefrontal cortex (Ozonoff et al, 1991). This issue has not been considered in patients widi frontal lesions, ^ a r t form die recent study by Charmon and

Crawford (2000). In this s tu ^ it was found diat patients with left anterior lesions showed impairment on the dieoiy-of-mind>type social comprdtension task, although patients also demonstrated deficits in executive function. Therefore, it was unclear whether theory o f mind or executive deficits contributed to this poor performance. To consider this issue they raised dnee hypotheses. Firstly, it was hypothesised that th ^ e might not be any relationship between dieory o f mind and executive function other than anatomical proximity in the fiontal lobes. Executive and theory o f mind impairment could arise separately due to damage to critical brain areas affecting both processes. A second hypodieas speculated that impairment was the result o f general executive impairment, radier dian a selective theory o f mind deficit Thirdly, it was suggested that there might be two separate routes to impaired performance, arising fiom disruption to broader executive impairment or to specific theory o f mind abdity. In odier words, lesions may cause executive impairment and smaller focal lesions may affect theory o f mind performance as a result o f selective deficits. They noted that recent models o f executive function (e.g. Shallice and Burgess, 1996) suggest that separable subcomponent processes exist and thus theory o f mind might represent one o f these. In considering diese hypotheses the researchers postulated that gmieralised executive impairment could account for die obsaved impairment without needing to evoke the concept o f theory o f mind, although it was acknowledged that further work was needed.

1.8.5.4. Experimental studies

Research examining dieory o f mind deficits following TBl is qiarse. As noted above, studies tapping higher-level dieory-of-mind-type social com prdiaision tasks will be reviewed in c h ^ ta diree. It is wordi noting that in a recent study by Charmon and Beeson (unpublished), TBl patiaits did not have difficulty performing a first order dieory ofrriind. Bara et al (1997) also found that TBl patients could adequately complete classical tests o f theory o f mind, including the ‘Smarties task’ (P em a et al, 1987).

There are a small number o f studies in die literature on empathy and TBL These have looked at the concept o f cognitive empathy. They toad to show reduced anpathy in TBl patients compared to healthy controls on self r^ o r t measures (e.g. Grattan and Eshnger, 1989; Grattan et al, 1994). The s tu ^ by Chaimon and Beeson (unpublished) was consistent with these findings, showing that TBl patients had a significantly reduced level o f cognitive empathy, compared to control participants. There is also evidence to suggest that TBl patiad m ^ report normal empathy one month post injury compared to relative reports but rato their empathy as more impaired at six months post injury (see Grattan and Eslinger, 1990).

1.8.5.5. Summary o f theory o f mind deficits

TBl results in behaviours that appear to reflect problems in dieory o f mind and cognitive empadqr. Experimental evidence suggests that first order dieory o f mind is intact in TBl patients, although studies tapping higher-level theory o f mind are few in number. There is evidence diat links dieory o f mind to the frontal lobes. However, diis anatomical link and the relationship between theory o f mind and executive function requires further elucidation.