![]() Attention-deficit/hyperactivity disorder overlaps substantially with externalizing disorders. Multiple pathway models of ADHD hypothesize that several factors including emotional and motivational processes and cognitive impairments contribute to the emergence of ADHD, but their relative importance and links to diagnostic presentations are debated (Castellanos et al., Reference Castellanos, Sonuga-Barke, Milham and Tannock2006 Martel, Reference Martel2009 Sergeant, Reference Sergeant2000). Dimensional analyses allow researchers to examine how symptoms of ADHD are associated with cognitive and physiological markers across the whole phenotypic continuum.ĭespite an extensive literature that documents cognitive impairment in ADHD, it is clear that ADHD symptomatology cannot be explained with reference to cognitive deficits alone (Brocki, Forslund, Frick, & Bohlin, Reference Brocki, Forslund, Frick and Bohlin2017 Castellanos, Sonuga-Barke, Milham, & Tannock, Reference Castellanos, Sonuga-Barke, Milham and Tannock2006 Martel, Reference Martel2009 Sjöwall, Roth, & Lindqvist, Reference Sjöwall, Roth and Lindqvist2013). ![]() Therefore, studies of symptom dimensions rather than discrete diagnostic entities have been advocated (Cuthbert, Reference Cuthbert2014). Attention-deficit/hyperactivity disorder symptoms are associated with negative social and educational outcomes and psychiatric comorbidity across the symptom spectrum (Holmberg & Bölte, Reference Holmberg and Bölte2014 Vogel et al., Reference Vogel, Ten Have, Bijlenga, de Graaf, Beekman and Kooij2018). In support of the dimensional view, studies have found the genetic factors that are related to ADHD as a diagnosis and to the broader phenotype to be highly similar (Demontis et al., Reference Demontis, Walters, Martin, Mattheisen, Als, Agerbo and Neale2019). ![]() It is increasingly recognized that ADHD symptoms are continuous, with the full syndrome representing the extreme end of traits that are found in the general population (Coghill & Sonuga-Barke, Reference Coghill and Sonuga-Barke2012 Greven, Asherson, Rijsdijk, & Plomin, Reference Greven, Asherson, Rijsdijk and Plomin2011). Consequently, ADHD presentations that are characterized primarily by one of these dimensions or by both of them are acknowledged. Although these symptom dimensions are highly correlated, they are considered to be dissociable. Horner syndrome is caused by interruption of the sympathetic nerves to an eye due from any cause.Attention-deficit/hyperactivity disorder (ADHD) is a diagnosis that is based on the presence of two symptom dimensions, inattention and hyperactivity/impulsivity (American Psychiatric Association, 2013). Horner syndrome refers to the combination of a constricted pupil, drooping eyelid, and loss of sweating around the affected eye. Disorders outside the brain that affect the sympathetic nervous system include tumors and injuries that involve the neck or upper part of the chest. Brain disorders that can affect these pathways include strokes, brain hemorrhage (spontaneous or due to head injury), and, less commonly, certain tumors or infections. Thus, people with nervous system disorders that affect the pupil often also have a drooping eyelid, double vision, and/or visibly misaligned eyes. These pathways carry nerve impulses to the pupil and to the muscles that control the eye and eyelid. This system works automatically (autonomously), without a person’s conscious. Nervous system disorders that cause unequal pupils are those that affect the 3rd cranial nerve or certain parts of the sympathetic or parasympathetic nervous system (the autonomic nervous system Overview of the Autonomic Nervous System The autonomic nervous system regulates certain body processes, such as blood pressure and the rate of breathing.
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