Traumatic brain injury (TBI) is the most common cause of brain damage, resulting in long-term disability. The "reserve" construct has been proposed to account for the reported mismatch between brain damage and its clinical expression. Although numerous studies have used various measures thought to reflect this construct, few studies have examined its underlying structure in clinical populations, and no studies have systematically studied this construct in TBI. In the present study, structural equation modeling technique was used to evaluate several models hypothesized to represent cognitive reserve (CR) in TBI. A broad range of data typically reported in the literature as representing CR was collected from 89 individuals who sustained moderate-to-severe TBI. Analyses revealed a best fitting model that consisted of three separate factors representing premorbid intelligence, socioeconomic status and leisure activity, with distinct pattern of associations among the three factors. Findings provide empirical support for the notion of a multi-factorial CR and suggest a coherent framework for further investigation. (JINS, 2013, 19, 1-8).

Altered brain connectivity accompanies autism spectrum disorders (ASD), but the relationship between connectivity and intellectual abilities, which often differs within ASD, and between ASD and typically developing (TD) children, is not understood. Here, diffusion tensor imaging (DTI) was used to explore the relationship between white matter integrity and non-verbal intelligence quotients (IQ) in children with ASD and in age- and gender-matched TD children. Tract-based spatial statistical analyses (TBSS) of DTI fractional anisotropy (FA) revealed altered relationships between white matter and IQ. Different relationships were found using within-group analyses, where regions of significant (p < .05, corrected) correlations in ASD overlapped minimally with regions of FA-IQ correlations in TD subjects. An additional between-groups analysis revealed significant correlation differences in widespread cortical and subcortical areas. These preliminary findings suggest altered brain connectivity may underlie some differences in intellectual abilities of ASD, and should be investigated further in larger samples as a function of development. (JINS, 2013, 19, 1-6).

Given the importance of identifying dementia prodromes for future treatment efforts, we examined two methods of diagnosing mild cognitive impairment (MCI) and determined whether empirically-derived MCI subtypes of these diagnostic methods were consistent with one another as well as with conventional MCI subtypes (i.e., amnestic, non-amnestic, single-domain, multi-domain). Participants were diagnosed with MCI using either conventional Petersen/Winblad criteria (n = 134; >1.5 SDs below normal on one test within a cognitive domain) or comprehensive neuropsychological criteria developed by Jak et al. (2009) (n = 80; >1 SD below normal on two tests within a domain), and the resulting samples were examined via hierarchical cluster and discriminant function analyses. Results showed that neuropsychological profiles varied depending on the criteria used to define MCI. Both criteria revealed an Amnestic subtype, consistent with prodromal Alzheimer's disease (AD), and a Mixed subtype that may capture individuals in advanced stages of MCI. The comprehensive criteria uniquely yielded Dysexecutive and Visuospatial subtypes, whereas the conventional criteria produced a subtype that performed within normal limits, suggesting its susceptibility to false positive diagnostic errors. Whether these empirically-derived MCI subtypes correspond to dissociable neuropathologic substrates and represent reliable prodromes of dementia will require additional follow-up. (JINS, 2013, 19, 1-11).

Sensorimotor inhibition, or the ability to filter out excessive or irrelevant information, theoretically supports a variety of higher-level cognitive functions. Impaired inhibition may be associated with increased impulsive and risky behavior in everyday life. Individuals infected with HIV frequently show impairment on tests of neurocognitive function, but sensorimotor inhibition in this population has not been studied and may be a contributor to the profile of HIV-associated neurocognitive disorders (HAND). Thirty-seven HIV-infected individuals (15 with HAND) and 48 non-infected comparison subjects were assessed for prepulse inhibition (PPI), an eyeblink startle paradigm measuring sensorimotor gating. Although HIV status alone was not associated with PPI deficits, HIV-positive participants meeting criteria for HAND showed impaired PPI compared to cognitively intact HIV-positive subjects. In HIV-positive subjects, PPI was correlated with working memory but was not associated with antiretroviral therapy or illness factors. In conclusion, sensorimotor disinhibition in HIV accompanies deficits in higher-order cognitive functions, although the causal direction of this relationship requires investigation. Subsequent research on the role of sensorimotor gating on decision-making and risk behaviors in HIV may be indicated. (JINS, 2013, 19, 1-9).

Children with traumatic brain injury (TBI) are at risk for social impairment. This study aimed to examine social function at 6 months post-TBI and to explore the contribution of injury, cognitive, and environmental influences. The sample included 136 children, 93 survivors of TBI, and 43 healthy controls. TBI participants were recruited on admission and underwent magnetic resonance imaging scan within 8 weeks of injury and behavioral assessment at 6 months post-injury. Healthy controls underwent magnetic resonance imaging scans and behavioral assessment on recruitment. Assessment included parent and child questionnaires tapping social outcome and child-direct testing of cognitive abilities important for social competence (communication, attention/executive function, social cognition). Injury characteristics and environmental measures were collected. At 6-months post-injury, social problems were evident, but not global. Social participation appeared most vulnerable, with more severe injuries leading to greater problems. Greater injury severity and poorer communication skills were associated with poorer social adjustment and social participation, with the impact of family function also significant. Processing speed, younger age, and male gender also contributed to social outcomes. Further follow-up is required to track the recovery of social skills and the changing influences of cognition, brain, and environment over time. (JINS, 2013, 19, 1-12).

Cognitive change is frequently observed in patients with Parkinson's disease (PD). However, the exact profile and extent of cognitive impairments remain unclear due to the clinical heterogeneity of PD and methodological issues in many previous studies. In this study, we aimed to examine the severity, frequency, and profile of cognitive changes in newly diagnosed PD patients over 5 years. At baseline and after 3 and 5 years, a hospital-based sample of PD patients (n = 59) and healthy controls (n = 40) were given neuropsychological tests covering six cognitive domains. Patients showed greater decline over time than healthy controls on all cognitive domains, except for attention. The profile of decline showed that psychomotor speed and memory were most affected. At the individual level 53% of the patients showed more cognitive decline than controls. Age at onset and memory impairment at baseline predicted cognitive decline. Cognitive functions in PD patients show greater decline in most domains than in healthy elderly over the course of 5 years. Due to selection bias as a result of attrition, the actual degree of decline may be greater than reported here. (JINS, 2013, 19, 1-14).

Core social interaction behaviors were examined in young children 0-36 months of age who were hospitalized for accidental (n = 61) or inflicted (n = 64) traumatic brain injury (TBI) in comparison to typically developing children (n = 60). Responding to and initiating gaze and joint attention (JA) were evaluated during a semi-structured sequence of social interactions between the child and an examiner at 2 and 12 months after injury. The accidental TBI group established gaze less often and had an initial deficit initiating JA that resolved by the follow-up. Contrary to expectation, children with inflicted TBI did not have lower rates of social engagement than other groups. Responding to JA was more strongly related than initiating JA to measures of injury severity and to later cognitive and social outcomes. Compared to complicated-mild/moderate TBI, severe TBI in young children was associated with less responsiveness in social interactions and less favorable caregiver ratings of communication and social behavior. JA response, family resources, and group interacted to predict outcomes. Children with inflicted TBI who were less socially responsive and had lower levels of family resources had the least favorable outcomes. Low social responsiveness after TBI may be an early marker for later cognitive and adaptive behavior difficulties. (JINS, 2013, 19, 1-11).

The present study investigated the impact of cue type and delay interval on prospective memory performance in depressed, compared to non-depressed, individuals using a clinically relevant measure, the Memory for Intentions Screening Test. The depressed group demonstrated impaired performance on time-based, but not event-based, prospective memory tasks relative to the nondepressed group. The depressed group also demonstrated impaired prospective memory on tasks with longer delay intervals (15 min), but not on tasks with shorter delay intervals (2 min). These data support theoretical frameworks that posit that depression is associated with deficits in cognitive initiative (i.e., reduced ability to voluntarily direct attention to relevant tasks) and thus that depressed individuals are susceptible to poor performance on strategically demanding tasks. The results also raise multiple avenues for developing interventions (e.g., implementation intentions) to improve prospective memory performance among individuals with depression, with potential implications for medication and other treatment adherence. (JINS, 2013, 19, 1-5).

Individuals with attention-deficit/hyperactivity disorder (ADHD) often exhibit deficits in processing information about time. Most studies, however, have required participants to perform active tasks and consequently it is unclear if performance deficits are due to impaired processing of temporal information, attentional deficits, or to impairments at a later stage of decision-making. This study used mismatch negativity (MMN) to examine automatic processing of temporal information in children with ADHD. The sample consisted of 11 children with typical development (8 boys; mean age/SD = 9.3/0.6 years) and 12 with ADHD (10 boys; mean age/SD = 8.9/0.8 years). Using the MMN paradigm, responses to standards and four deviants (hard/easy frequency, hard/easy duration) were elicited during the same sequence. The children's ability to actively discriminate each deviant was also assessed. Both groups exhibited MMNs to all deviants suggesting successful automatic discrimination. Furthermore, amplitude and latency measures were roughly comparable across groups. No group differences were seen on the active discrimination task, but performance was worse for duration than for frequency deviants. These results suggest that children with ADHD are able to automatically process temporal information, so deficits reported in active discrimination paradigms are likely due to deficits in subjective perception or usage of temporal information. (JINS, 2013, 19, 1-9).