Aberrant functional brain connectome in people with antisocial personality disorder

Antisocial personality disorder (ASPD) is characterised by a disregard for social obligations and callous unconcern for the feelings of others. Studies have demonstrated that ASPD is associated with abnormalities in brain regions and aberrant functional connectivity. In this paper, topological organisation was examined in resting-state fMRI data obtained from 32 ASPD patients and 32 non-ASPD controls. The frequency-dependent functional networks were constructed using wavelet-based correlations over 90 brain regions. The topology of the functional networks of ASPD subjects was analysed via graph theoretical analysis. Furthermore, the abnormal functional connectivity was determined with a network-based statistic (NBS) approach. Our results revealed that, compared with the controls, the ASPD patients exhibited altered topological configuration of the functional connectome in the frequency interval of 0.016–0.031 Hz, as indicated by the increased clustering coefficient and decreased betweenness centrality in the medial superior frontal gyrus, precentral gyrus, Rolandic operculum, superior parietal gyrus, angular gyrus, and middle temporal pole. In addition, the ASPD patients showed increased functional connectivity mainly located in the default-mode network. The present study reveals an aberrant topological organisation of the functional brain network in individuals with ASPD. Our findings provide novel insight into the neuropathological mechanisms of ASPD.

The function networks for each participant were constructed using two parcellation methods (L-Crad and H-1024).
Data are expressed as the mean ± SD. (*: p< 0.05)   Some regions with significantly decreased nodal betweenness were found in the frontal lobe (i.e. the right Rolandic operculum, the right precentral gyrus, and the right medial superior frontal gyrus), and the findings were quite consistent with the previous studies of the structural and functional abnormalities of ASPD subjects. Impulsive aggressive acts have been associated with reduced metabolism in the superior medial frontal. The precentral gyrus is part of the primary motor cortex and the deficit in precentral gyrus may increase the chance of future aggression. A recent study has reported a significantly positive correlation between a negative behavioural urgency and the grey matter volumes in the right Rolandic operculum in personality disorders with antisocial diagnosis 3 . These findings persistently suggest that the aberrant nodal betweenness in these three frontal regions might be partially involved in the violent and aggressive behaviours of ASPD individuals.
A significantly decrease in nodal betweenness centrality was observed in subjects with ASPD in the parietal lobe (the right superior parietal gyrus and left angular gyrus). Superior parietal cortex is critical for the manipulation and rearrangement of information in working memory. The superior parietal lobe is also crucial for sensorimotor integration to maintain an internal representation of the body's state. A reduced metabolism has been found in the superior parietal cortex in aggressive patients 4 , murderers 5 and individuals with impulsive personality disorders 6 .
Hence, the functions of the superior parietal lobe are important for the selection and control of socially relevant behaviours. Other cognitive systems are likely to be affected if the functions of the superior parietal lobe are impaired. Moreover, violent criminals are also shown to have a reduced glucose metabolism 5 and blood flow 7 in the angular gyrus. It has been argued that the angular gyrus was associated with the sense of responsibility for one's actions, the lack of which may contribute to immoral behaviour of ASPD individuals 8 .
Besides, the temporal lobe is another major brain area associated with antisocial and aggressive behaviour 4 . In our previous study, ASPD subjects were found with a higher ReHo value in the temporal gyrus when compared with control subjects 9 , and a higher ReHo value indicates a higher glucose metabolism. Hence, this is consistent with our findings of an increased nodal betweenness in the left middle temporal gyrus. Nevertheless, in this study, a significantly decreased nodal betweenness centrality was observed in left middle temporal pole of the ASPD group.
Many studies have shown the temporal poles are essential for cognitive empathy 10 , and the damage to the middle temporal pole may cause the development of cold-bloodedness, one of major characteristics of ASPD.
In this study, all of the ROIs are related to symptoms of depersonalization. The abnormal nodal betweenness may be connected to the high impulsivity, lack of conscience and cold-bloodedness of ASPD. reference：