Soft neurological signs in ADHD

Abstract

ADHD is a common childhood neurobehavioural disorder defined by symptoms of developmentally inappropriate inattention, impulsivity and hyperactivity. A recent meta-analysis estimated the worldwide prevalence of ADHD to be 5.29%, making it the most prevalent psychiatric disorder of childhood. The social and economic costs of childhood ADHD are considerable, and difficulties often persist into adulthood. Children with ADHD are at high risk for developing adjustment problems, antisocial behaviour, substance abuse, other psychiatric disorders, and difficulties in education and work. Motor skill problems and neurological soft signs have been associated with inattention and behaviour difficulties for decades. Concurrent developmental coordination disorder (DCD) is reported in about 50% of children with ADHD, mainly correlated to combined or inattentive subtypes. The earlier minimal brain dysfunction term included soft signs or motor problems as signs of neurological dysfunction. Some authors argue that these signs should be included in the diagnostics of ADHD. A review found that movement behaviour in ADHD were described in 49 papers between 1949 and 2002; indicating that movement skill difficulties, poor level of physical fitness and concurrent DCD are frequent in ADHD. Movement skill difficulties often reported are impaired timing , impaired hand dexterity/fine motor coordination , "motor overflow" and neurological soft signs. Many of these terms indicate difficulties inhibiting motor responses, which is a consistent finding in ADHD and seemingly varies with task complexity. Balance problems are also often reported in ADHD and are thought to be of cerebellar origin . Cerebellar abnormalities may also be involved in other motor problems in ADHD. A meta-analysis of structural neuroimaging studies in ADHD found prominent reductions in cerebellum, and a recent diffusion tensor study in youths with ADHD showed increased fractional anisotropy in white matter pathways connecting prefrontal and parietal-occipital areas with striatum and cerebellum. Deficient signalling of the prefrontal cortex (PFC) by parietal cortex, basal ganglia and cerebellum may underlie the poor cognitive, motor and behaviour adjustment in ADHD. The motor problems in ADHD may thus be due to poor adjustment in different contexts rather than primary motor deficits, explaining the variability in performance often reported in the ADHD literature. So, in an effort to evaluate the association of soft neurological signs with the diagnosis, symptom domains and severity of ADHD in a sample of Egyptian children, we introduce this work. NSS are minor abnormalities like poor motor coordination, sensory perceptual difficulties, and difficulties in sequencing of complex motor tasks. They lack definitive localizing significance but are indicative of subtle brain dysfunction. Some studies reported higher scores of NSS in psychiatric patients especially in patients with schizophrenia or OCD. Many differences were found between these dimensions including neurological, cognitive and anatomical abnormalities. This study aimed to study the presence of NSS in ADHD patients in comparison with healthy individuals and clinical characters of the patients with increased NSS including cognitive dysfunctions. The study included 2 parts: Theoretical part Included 2 chapters: Chapter 1: Review of literature about ADHD including epidemiology, etiology, clinical picture, cognitive dysfunctions and treatment of the disease. Chapter 2: Review of literature about NSS including definition, localization, hereditary and presence in different psychiatric disorders especially ADHD.