Adult Age Differences in Self-Reported Pain and Anterior CSF Space in Chiari Malformation.

Chiari malformation type I (CMI) is a neural disorder with sensory, cognitive, and motor defects, as well as headaches. Radiologically, the cerebellar tonsils extend below the foramen magnum. To date, the relationships among adult age, brain morphometry, surgical status, and symptom severity in CMI are unknown. The objective of this study was to better understand the relationships among these variables using causal modeling techniques. Adult CMI patients (80% female) who either had (n = 150) or had not (n = 151) undergone posterior fossa decompression surgery were assessed using morphometric measures derived from magnetic resonance images (MRI). MRI-based morphometry showed that the area of the CSF pocket anterior to the cervico-medullary junction (anterior CSF space) correlated with age at the time of MRI (r = - .21). Also, self-reported pain increased with age (r = .11) and decreased with anterior CSF space (r = - .18). Age differences in self-reported pain were mediated by anterior CSF space in the cervical spine area-and this effect was particularly salient for non-decompressed CMI patients. As CMI patients age, the anterior CSF space decreases, and this is associated with increased pain-especially for non-decompressed CMI patients. It is recommended that further consideration of age-related decreases in anterior CSF space in CMI patients be given in future research.

Revisiting the factor structure of the Short-Form McGill Pain Questionnaire-2 (SF-MPQ-2): Evidence for a bifactor model in individuals with Chiari malformation.

The Short-Form McGill Pain Questionnaire-2 (SF-MPQ-2; Dworkin et al., 2009) is intended to measure the multidimensional qualities of pain (i.e., continuous, intermittent, neuropathic, and affective) as well as total pain. Using structural equation modeling, we evaluated the fit of four competing measurement models of the SF-MPQ-2-an oblique 4-factor model, a 1-factor model, a higher-order model, and a bifactor model-in 552 adults diagnosed with Chiari malformation, a chronic health condition whose primary symptoms include head and neck pain. Results revealed the strongest support for the bifactor model, suggesting that SF-MPQ-2 item responses are due to both a general pain factor and a specific pain factor that is orthogonal to the general pain factor. Additional bifactor analyses of the SF-MPQ-2's model-based reliability and dimensionality revealed that most of the SF-MPQ-2's reliable variance is explained by a general pain factor, and that the instrument can be modeled unidimensionally and scored as a general pain measure. Results also indicated that the general and affective pain factors in the bifactor model uniquely predicted pain-related external criteria (e.g., depression, anxiety, and stress); however, the continuous, intermittent, and neuropathic factors did not.

Relation of individual differences in impulsivity to nonclinical emotional decision making.

Impulsivity has been identified as a behavioral precursor to addiction, and may be the manifestation of a neurological vulnerability. The present study investigated whether individual differences in impulsivity were associated with performance on the Iowa Gambling Task (IGT, a test of emotional decision making thought to be associated in part with ventromedial prefrontal cortex function) and the Wisconsin Card Sorting Task (WCST, a set-shifting thought to be associated in part with dorsolateral prefrontal cortex function). Subjects were screened for impulsivity using the BIS-11 (self-report) and a delay discounting questionnaire (a behavioral measure of impulsivity). High impulsivity was associated with poorer performance on the final block of trials of the IGT but was not significantly related to WCST performance. Both measures were significantly correlated with scores on the BIS. These results provide support for hypothesis that, in a nonclinical sample, impulsivity may vary systematically with performance on neuropsychological indicators of prefrontal function.

Influence of mild cognitive impairment on visual word recognition.

The present study examined the effects of normal aging and mild cognitive impairment (MCI) on visual word recognition. Madden et al. (1999) reported evidence of general slowing of cognitive processes in Alzheimer's disease (AD) patients relative to younger adults and healthy older adults using a lexical decision task. It was of interest to determine whether similar effects would be observed in MCI patients relative to healthy younger and older adults. We extended the lexical decision task paradigm developed by Allen et al. (2004b) on younger adults to an examination of the effect(s) of MCI on visual word recognition. Results from the present study showed that healthy older adults and MCI patients performed similarly. That is, both groups took longer than younger adults to process words presented in mixed-case than in consistent-case letters. Mild cognitive impairment patients, however, responded significantly more slowly than healthy older adults across all lexical decision task conditions and showed a trend toward larger case-mixing effects than healthy older adults, which suggests that MCI may result in poorer analytic processing ability. Based on the current findings, evidence of a generalized slowing of cognitive processes using a standard lexical decision task can be expanded to include not only AD patients, but also the preclinical stages of the disease as well.

Olfactory learning and memory impairments following lesions to the hippocampus and perirhinal-entorhinal cortex.

The role of the hippocampus and perirhinal-entorhinal cortex was examined in an olfactory discrimination paradigm. Small neurotoxic lesions of the hippocampus (21% tissue damage) yielded relatively unimpaired olfactory retention across brief (30 s), intermediate (approximately 5 min), and 24-hr delays, whereas impairments were noted at 5-day retention intervals. Larger hippocampal lesions (63% tissue damage) spared memory at intermediate delays, with no impact at 8-day retention intervals. Aspiration lesions directed at the perirhinal-entorhinal cortex produced a variable performance pattern, with impairments noted at intermediate, 24-hr, and 5-day delays. Results suggest the hippocampus is not specifically involved in retaining olfactory information, with additional consideration given to the relationship between lesion size and memory impairment.

Electrophysiological evidence for adult age-related sparing and decrements in emotion perception and attention.

The present study examined adult age differences in processing emotional faces using a psychological refractory period paradigm. We used both behavioral and event-related potential (P1 component) measures. Task 1 was tone discrimination (fuzzy vs. pure tones) and Task 2 was emotional facial discrimination ("happy" vs. "angry" faces). The stimulus onset asynchrony (SOA) between the two tasks was 100, 300, and 900 ms. Earlier research observed larger age deficits in emotional facial discrimination for negative (angry) than for positive (happy) faces (Baena et al., 2010). Thus, we predicted that older adults would show decreased attentional efficiency in carrying out dual-task processing on the P1 (a component linked to amygdalar modulation of visual perception; Rotshtein et al., 2010). Both younger and older groups showed significantly higher P1 amplitudes at 100- and 300-ms SOAs than at the 900-ms SOA, and this suggests that both age groups could process Task 2 faces without central attention. Also, younger adults showed significantly higher P1 activations for angry than for happy faces, but older adults showed no difference. These results are consistent with the idea that younger adults exhibited amygdalar modulation of visual perception, but that older adults did not.

On age differences in prefrontal function: the importance of emotional/cognitive integration.

Evidence of prefrontal cortex decline among healthy older adults has been widely reported, although many questions remain regarding the functional heterogeneity of the prefrontal lobes and the uniformity (or lack thereof) with which discrete regions decline with age. MacPherson, Phillips, and Della Sala (2002) previously reported age differences in tasks associated with dorsolateral prefrontal cortex (DLPFC) function (executive control), but not for tasks associated with ventromedial prefrontal cortex (VMPFC) function (emotional/cognitive integration). The present study, conducted using 39 younger adults and 39 older adults, replicates the MacPherson et al. findings regarding DLPFC functioning. However, and perhaps due to the use of more sensitive tasks, we also find age differences in tasks associated with VMPFC function. Specifically, both univariate and multivariate analyses indicated older adults showed deficits across the DLPFC and VMPFC tasks. Exploratory factor analysis of the task performance scores indicated four underlying dimensions, two related to DLPFC functioning and two related to VMPFC functioning. A set of structural equation models specifying age effects on the four task performance factors was tested, in order to contrast models of process-specific vs. common age effects. Our results suggest that older adults show deficits in emotional/cognitive integration as well as in executive function, and that those effects do include process-specific age deficits.

A multistream model of visual word recognition.

Four experiments are reported that test a multistream model of visual word recognition, which associates letter-level and word-level processing channels with three known visual processing streams isolated in macaque monkeys: the magno-dominated (MD) stream, the interblob-dominated (ID) stream, and the blob-dominated (BD) stream (Van Essen & Anderson, 1995). We show that mixing the color of adjacent letters of words does not result in facilitation of response times or error rates when the spatial-frequency pattern of a whole word is familiar. However, facilitation does occur when the spatial-frequency pattern of a whole word is not familiar. This pattern of results is not due to different luminance levels across the different-colored stimuli and the background because isoluminant displays were used. Also, the mixed-case, mixed-hue facilitation occurred when different display distances were used (Experiments 2 and 3), so this suggests that image normalization can adjust independently of object size differences. Finally, we show that this effect persists in both spaced and unspaced conditions (Experiment 4)--suggesting that inappropriate letter grouping by hue cannot account for these results. These data support a model of visual word recognition in which lower spatial frequencies are processed first in the more rapid MD stream. The slower ID and BD streams may process some lower spatial frequency information in addition to processing higher spatial frequency information, but these channels tend to lose the processing race to recognition unless the letter string is unfamiliar to the MD stream--as with mixed-case presentation.

An emotional mediation theory of differential age effects in episodic and semantic memories.

Although there is a large decrement in central episodic memory processes as adults age, there is no appreciable decrement in central semantic memory processes (Allen et al., Journal of Gerontology: Psychological Sciences, 57B, P173-P186, 2002; Allen et al., Experimental Aging Research, 28, 111-142, 2002; Mitchell, Journal of Experimental Psychology: Learning, Memory, and Cognition, 15, 31-49, 1989). The authors develop a theory of episodic memory's connections to cognitive, emotional, and motivational systems to explain these differential age effects. The theory is discussed within the context of the cognitive neuroscience research regarding limbic system connectivity in conjunction with Damasio's notion of somatic markers (Descartes' error: Emotion, reason, and the human brain, New York: Grosset/Putnam, 1994). The central hypothesis is that elements of limbic system circuitry, including portions of the medial temporal lobes and frontal cortex, are associated with both working and long-term episodic memory performance, and by extension, with the capacity to engage in emotion-guided, self-regulatory processes that depend heavily on episodic memory. In contrast, the semantic memory system may have less shared interface with episodic and affective networks (i.e., the limbic-related system), and therefore remain independent of neurocognitive changes impacting emotional states and episodic-type memory processes. Accordingly, this framework may account for the pattern of age-related declines in episodic relative to semantic memory, particularly if older adults experience less emotional activation, and therefore fewer somatic markers, than younger adults. An initial empirical examination of this emotional mediation theory is presented, using preexisting data that include indicators of age, chronic tendency to focus on negative emotional stimuli (neuroticism), and working memory performance.

Reports of head injury and symptom knowledge among college athletes: implications for assessment and educational intervention.

OBJECTIVE: To identify the prevalence of head injuries and related symptoms among college athletes and examine knowledge of head injury consequences and behavioral tendencies of athletes in the presence of symptoms. DESIGN: Retrospective survey. PARTICIPANTS: A total of 461 male and female athletes beginning competitive play at the University of Akron (Akron, OH) during the years 1995 to 2001. MAIN OUTCOME MEASURES: Responses to survey questions were analyzed to determine the frequency of concussions and injury-related symptoms (eg, dizziness, headache, nausea or vomiting) in addition to behavioral responses in the presence of certain symptoms (eg, playing with headache, failure to report symptoms while playing). Written responses to queries regarding symptom knowledge were analyzed for thematic content and were used to identify deficiencies in signs and symptoms of concussion. RESULTS: Nearly 32% of all athletes had experienced a blow to the head causing dizziness, with over 1/4 confirming various somatic symptoms following a blow to the head (eg, seeing stars, nausea or vomiting, head pain). Continuing to play despite symptom presence was noted (eg, dizziness, 28.2%; headache, 30.4%), with 19.5% reporting a concussion diagnosis. Knowledge of head injury consequences was found to be deficient, with 56% indicating no knowledge of the possible consequences following a head injury. Of those providing responses, the majority reflected awareness of cognitive (eg, memory problems) and physical (eg, brain damage) consequences. CONCLUSIONS: A sizable number of athletes may enter collegiate play with a previous concussion diagnosis, and many more are likely to have experienced symptoms suggestive of a mild head injury. Of considerable concern is the tendency to play while symptomatic (eg, headache, dizziness) and the failure to report symptoms while playing--especially among football players (25.2%). The apparent deficiency in athlete knowledge of head injury consequences raises concern regarding athlete recognition of potentially problematic symptoms and represents an important area for educational intervention.