Towards an understanding of unique and shared pathways in the psychopathophysiology of ADHD

Most attention deficit hyperactivity disorder (ADHD) research has compared cases with unaffected controls. This has led to many associations, but uncertainties about their specificity to ADHD in contrast with other disorders. We present a selective review of research, comparing ADHD with other disorders in neuropsychological, neurobiological and genetic correlates. So far, a specific pathophysiological pathway has not been identified. ADHD is probably not specifically associated with executive function deficits. It is possible, but not yet established, that ADHD symptoms may be more specifically associated with motivational abnormalities, motor organization and time perception. Recent findings indicating common genetic liabilities of ADHD and other conditions raise questions about diagnostic boundaries. In future research, the delineation of the pathophysiological mechanisms of ADHD needs to match cognitive, imaging and genetic techniques to the challenge of defining more homogenous clinical groups; multi-site collaborative projects are needed.     

Characterizing the ADHD phenotype for genetic studies

The genetic study of ADHD has made considerable progress. Further developments in the field will be reliant in part on identifying the most appropriate phenotypes for genetic analysis. The use of both categorical and dimensional measures of symptoms related to ADHD has been productive. The use of multiple reporters is a valuable feature of the characterization of psychopathology in children. It is argued that the use of aggregated measures to characterize the ADHD phenotype, particularly to establish its pervasiveness, is desirable. The recognition of the multiple comorbidities of ADHD can help to isolate more specific genetic influences. In relation to both reading disability and conduct disorder there is evidence that genes may be involved in the comorbid condition that are different from pure ADHD. To date, progress with the investigation of endophenotypes for ADHD has been disappointing. It is suggested that extending such studies beyond cognitive underpinnings to include physiological and metabolic markers might facilitate progress.     

A Danish version of the Sensation Seeking Scale and its relation to a broad spectrum of behavioral and psychological characteristics

The primary purpose of the present study was to evaluate the internal consistency and construct validity of the Danish translation of Zuckerman's Sensation Seeking Scale (SSS). The secondary aim was to extend the range of psychological variables and behaviors that have been related to sensation seeking. The sample consisted of 691 subjects (363 males and 328 females) with a mean age of 31.7 years. The internal consistency of the scales was evaluated by coefficient alpha and intercorrelations among the five scales derived from the SSS were computed. Information on other variables was collected through standardized tests as well as questionnaires and interviews developed especially for this study. The results showed that the Danish SSS is a psychometrically sound instrument and revealed the relationship between sensation seeking and a broad spectrum of psychological traits and behaviors: socioeconomic status, academic achievement, intelligence, personality, smoking, alcohol and drug use, sexuality, driving and public transportation violations, and leisure time activities. Thus, this study confirmed and expanded the findings of many previous studies, while the results supported the validity of the Danish SSS and corroborated the usefulness of the concept of sensation seeking.     

The Presumption of Nothingness

Several distinguished philosophers have argued that since the state of affairs where nothing exists is the simplest and least arbitrary of all cosmological possibilities, we have reason to be surprised that there is in fact a non-empty universe. We review this traditional argument, and defend it against two recent criticisms put forward by Peter van Inwagen and Derek Parfit. Finally, we argue that the traditional argument nevertheless needs reformulation, and that the cogency of the reformulated argument depends partly on whether there are certain conceptual limitations to what a person can hypothetically doubt.     

The Relationship of Functional Variables and Psychopathology to Aggressive Behavior in Persons With Severe and Profound Mental Retardation

A number of hypotheses have emerged regarding the etiology of physical aggression in persons with mental retardation. Although a multicomponent model is appropriate, results of functional analysis-based studies have yielded promising results in identifying instigating and maintaining factors of aggression. However, the relationship between functional variables and conditions such as psychiatric diagnosis to aggressive behavior has yet to be investigated in persons with mental retardation. We conducted a study examining the prevalence of environmental or physical factors in aggressive behavior in mentally retarded persons with and without psychiatric disturbance. One hundred and thirty-five individuals with mental retardation who exhibited physical aggression were assessed with the Questions About Behavior Function Scale (QABF) to identify environmental or physical contribution to aggressive behavior. One or more behavioral functions were identified for 75% of the participants. Additionally, of 66 of the participants scoring above the clinical cutoff on an assessment for dual diagnosis, 75% met criteria for an environmental or physical function for aggression. No significant differences in number of participants with an identifiable function of aggression were found between the no dual diagnosis and dual diagnosis groups. Our findings underscore the importance of identifying functions underlying aggressive behavior in persons with mental retardation, and the need to consider functional variables regardless of psychiatric condition in treatment planning efforts for such individuals.     

Color And The Duplication Assumption

Susan Hurley has attacked the 'Duplication Assumption', the assumption thatcreatures with exactly the same internal states could function exactly alike inenvironments that are systematically distorted. She argues that the dynamicalinterdependence of action and perception is highly problematic for the DuplicationAssumption when it involves spatial states and capacities, whereas no such problemsarise when it involves color states and capacities. I will try to establish that theDuplication Assumption makes even less sense for lightness than for some ofthe spatial cases. This is due not only to motor factors, but to the basic physicalasymmetry between black and white. I then argue that the case can be extendedfrom lightness perception to hue perception. Overall, the aims of this paper are:(1) to extend Susan Hurley's critique of the Duplication Assumption; (2) to argueagainst highly constrained versions of Inverted Spectrum arguments; (3) to proposea broader conception of the vehicle for color perception.     

Infant responsiveness and maternal confidence in the neonatal period

Responsiveness in prematurely and term-born infants was studied cross-sectionally in relation to maternal confidence. Orientation and arousal were measured in 140 prematurely (mean BW 1,398 g, GA 30.1 weeks) and 75 term-born infants (mean BW 3,613 g, GA 39.3 weeks) with the Neonatal Behavioral Assessment Scales. Mothers filled out the Maternal Confidence Questionnaire and a modified version of the Parenting Stress Index. Prematurely born infants had a significantly lower level of arousal than term-born neonates. Responsiveness was not associated with maternal confidence. Lower confidence was associated with primiparity in both groups of mothers. Multiparous mothers of prematurely born infants had significantly lower levels of confidence than multiparous mothers of term-born infants. Confidence was significantly associated with stress for mothers of prematurely and term-born infants, and may be focused in follow-up after giving birth. Prematurely born infants should be examined more thoroughly in aspects of arousal at the time of discharge.