Psychiatric comorbidities in asperger syndrome and high functioning autism: diagnostic challenges
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Several psychiatric conditions, both internalizing and externalizing, have been documented in comorbidity with Asperger Syndrome (AS) and High Functioning Autism (HFA). In this review we examine the interplay between psychiatric comorbidities and AS/HFA. In particular, we will focus our attention on three main issues. First, we examine which psychiatric disorders are more frequently associated with AS/HFA. Second, we review which diagnostic tools are currently available for clinicians to investigate and diagnose the associated psychiatric disorders in individuals with AS/HFA. Third, we discuss the challenges that clinicians and researchers face in trying to determine whether the psychiatric symptoms are phenotypic manifestations of AS/HFA or rather they are the expression of a distinct, though comorbid, disorder. We will also consider the role played by the environment in the manifestation and interpretation of these symptoms. Finally, we will propose some strategies to try to address these issues, and we will discuss therapeutic implications.
Is it possible that the high levels of anxiety and depression found in Asperger’s and High Functioning Autism is related to the immune system ? Is further work required to physiologically identify differing phenotypes in autism and begin to understand a longitudinal picture of how the immune system and the child operate and to what risk they are at for further mental health complications ?
From provisional PDF
“As illustrated in Table 1, several studies reported an association between AS/HFA and internalizing symptoms, in particular depression [6-11], bipolar disorders  and anxiety [33,34].”
“An association between AS/HFA and attention deficit hyperactivity disorder (ADHD) and other externalizing disorders such as disruptive behavior and conduct disorders.”
Inflammation in anxiety.
The idea of the existence of an interaction between the immune system and the central nervous system (CNS) has prompted extensive research interest into the subject of “Psychoneuroimmunology” taking the field to an interesting level where new hypotheses are being increasingly tested.
Specifically, exactly how the cross talk of pathways and mechanisms enable immune system to influence our brain and behavior is a question of immense significance. Of particular relevance to this topic is the role of cytokines in regulating functions within the CNS that ultimately modulate behavior. Interestingly, psychological stress is reported to modulate cytokine production, suggesting potential relevance of this mediator to mental health. In fact, cytokine signaling in the brain is known to regulate important brain functions including neurotransmitter metabolism, neuroendocrine function, synaptic plasticity, as well as the neural circuitry of mood. It is rather obvious to expect an aberrant behavioral outcome as a result of a dysregulation in cytokine signaling which might lead to occurrence of depression, anxiety, and cognitive dysfunction. Thus, understanding the mechanisms by which the immune system influences behavior would reveal targets for potential therapeutic development as well as strategies for the prevention of neuropsychiatric diseases. To date, the presence of inflammatory responses and the crucial role of cytokines in depression have received most attention. However, considering a big socioeconomic impact due to an alarming increase in anxiety disorder patients, there is an urgent research need for a better understanding of the role of cytokines in anxiety. In this review, we discuss recent research on the role of neuroimmunology in anxiety. At the end, we offer an “oxidative stress theory,” which we propose works perhaps as a “sensor of distress,” the imbalance of which leads to neuroinflammation and causes anxiety disorders. Much research is needed to extensively test this theory keeping an open mind!
Immune system to brain signaling: neuropsychopharmacological implications.
There has been an explosion in our knowledge of the pathways and mechanisms by which the immune system can influence the brain and behavior. In the context of inflammation, pro-inflammatory cytokines can access the central nervous system and interact with a cytokine network in the brain to influence virtually every aspect of brain function relevant to behavior including neurotransmitter metabolism, neuroendocrine function, synaptic plasticity, and neurocircuits that regulate mood, motor activity, motivation, anxiety and alarm. Behavioral consequences of these effects of the immune system on the brain include depression, anxiety, fatigue, psychomotor slowing, anorexia, cognitive dysfunction and sleep impairment; symptoms that overlap with those which characterize neuropsychiatric disorders, especially depression. Pathways that appear to be especially important in immune system effects on the brain include the cytokine signaling molecules, p38 mitogen-activated protein kinase and nuclear factor kappa B; indoleamine 2,3 dioxygenase and its downstream metabolites, kynurenine, quinolinic acid and kynurenic acid; the neurotransmitters, serotonin, dopamine and glutamate; and neurocircuits involving the basal ganglia and anterior cingulate cortex. A series of vulnerability factors including aging and obesity as well as chronic stress also appears to interact with immune to brain signaling to exacerbate immunologic contributions to neuropsychiatric disease. The elucidation of the mechanisms by which the immune system influences behavior yields a host of targets for potential therapeutic development as well as informing strategies for the prevention of neuropsychiatric disease in at risk populations.