Alexithymia in Parkinson’s Disease: Secondary Phenomenon Or Primary Neuropsychiatric feature?

Abstract

ISSN 1758-2024 10.2217/NMT.12.31 © 2012 Future Medicine Ltd Neurodegen. Dis. Manage. (2012) 2(4), 343–346 part of Parkinson’s disease (PD) is a neuro­ degenerative disorder previously thought to be almost exclusively characterized by motor symptoms such as rigidity, brady­ kinesia, postural instability and rest tremor. However, motor symptoms are only one aspect of this multifaceted and complex disorder, which is also character­ ized by non­motor phenomena such as mood and anxiety disorders [1,2], impair­ ment of facial emotion expression recog­ nition [3,4], affective prosody and verbal emotional communication [5,6]. Alexithymia is one PD non­motor phe­ nomenon that is still poorly understood. It was originally defined as the inability to recognize and verbalize emotions [7]. People with alexithymia have reduced or missing imagery, they lack introspection ability and are inclined to adopt conform­ ist behavior. They frequently develop dependent relationships or, alternatively, prefer social isolation. Generally, people with alexithymia are unable to symbol­ ize or mentalize emotions. Indeed, these patients do not cognitively elaborate emo­ tions or conceptualize them by mental imaging or words. In alexithymic patients, emotion is just a physical and presymbolic perception. Therefore, alexithymia may be related to lost or reduced empathetic ability and, thus, may negatively affect other aspects of emotional processing, such as recog­ nition of facial emotion expressions. In other words, ‘if I am unable to compre­ hend, give meaning to and recognize my emotions how can I understand and feel other people’s emotions?’ In this regard, the brain structures that respond to emo­ tions have also been shown to be activated during the process of identification of the same emotions by others [8,9], suggesting that anatomical or functional derange­ ment of discrete neural pathways may lead to the inability to experience emotions as well as impaired recognition of the emo­ tions expressed by others. In particular, the ability to attribute mental states to others to understand and predict their emotional behavior, that is, the so­called empathetic process, requires the inter­ vention of several structures such as the amygdala, the temporal lobe (particularly