Dynamic associations between glucose and ecological momentary cognition in Type 1 Diabetes.

Type 1 diabetes (T1D) is a chronic condition characterized by glucose fluctuations. Laboratory studies suggest that cognition is reduced when glucose is very low (hypoglycemia) and very high (hyperglycemia). Until recently, technological limitations prevented researchers from understanding how naturally-occurring glucose fluctuations impact cognitive fluctuations. This study leveraged advances in continuous glucose monitoring (CGM) and cognitive ecological momentary assessment (EMA) to characterize dynamic, within-person associations between glucose and cognition in naturalistic environments. Using CGM and EMA, we obtained intensive longitudinal measurements of glucose and cognition (processing speed, sustained attention) in 200 adults with T1D. First, we used hierarchical Bayesian modeling to estimate dynamic, within-person associations between glucose and cognition. Consistent with laboratory studies, we hypothesized that cognitive performance would be reduced at low and high glucose, reflecting cognitive vulnerability to glucose fluctuations. Second, we used data-driven lasso regression to identify clinical characteristics that predicted individual differences in cognitive vulnerability to glucose fluctuations. Large glucose fluctuations were associated with slower and less accurate processing speed, although slight glucose elevations (relative to person-level means) were associated with faster processing speed. Glucose fluctuations were not related to sustained attention. Seven clinical characteristics predicted individual differences in cognitive vulnerability to glucose fluctuations: age, time in hypoglycemia, lifetime severe hypoglycemic events, microvascular complications, glucose variability, fatigue, and neck circumference. Results establish the impact of glucose on processing speed in naturalistic environments, suggest that minimizing glucose fluctuations is important for optimizing processing speed, and identify several clinical characteristics that may exacerbate cognitive vulnerability to glucose fluctuations.

Genotoxicity of irinotecan and its modulation by vitamins A, C and E in human lymphocytes from healthy individuals and cancer patients.

Many patients being treated for cancer use dietary supplements, particularly antioxidants, in the hope of reducing the toxicity of chemotherapy or radiotherapy. However, clinicians should advise their patients against using antioxidant dietary supplements during chemotherapy. Irinotecan (CPT-11) is a common chemotherapeutic agent, but it causes side effects, including genotoxicity with damages the DNA of blood cells. The aim of this work was to evaluate the modulating effect of A, C and E vitamins on genotoxic activity of irinotecan (CPT-11) and to analyse the efficacy of DNA repair in lymphocytes of both patients with diagnosed colorectal carcinoma and healthy individuals in vitro. In healthy donors' cells CPT-11 did not exert a strong, genotoxic effect, both in the presence of vitamins and without them. In turn, a statistically significant increase of DNA migration in the comet tails was noted in patients' lymphocytes. The presence of vitamins A, C and E in incubation solutions acted synergistically, increasing the level of DNA lesions in cells caused by the exposure of the material on tested irinotecan concentrations. Analysis of the efficacy of DNA repair, performed after 2h of postincubation, showed the decrease of DNA percentage in comet tails in all experimental samples.

Cognitive activities delay onset of memory decline in persons who develop dementia.

BACKGROUND: Persons destined to develop dementia experience an accelerated rate of decline in cognitive ability, particularly in memory. Early life education and participation in cognitively stimulating leisure activities later in life are 2 factors thought to reflect cognitive reserve, which may delay the onset of the memory decline in the preclinical stages of dementia. METHODS: We followed 488 initially cognitively intact community residing individuals with epidemiologic, clinical, and cognitive assessments every 12 to 18 months in the Bronx Aging Study. We assessed the influence of self-reported participation in cognitively stimulating leisure activities on the onset of accelerated memory decline as measured by the Buschke Selective Reminding Test in 101 individuals who developed incident dementia using a change point model. RESULTS: Each additional self-reported day of cognitive activity at baseline delayed the onset of accelerated memory decline by 0.18 years. Higher baseline levels of cognitive activity were associated with more rapid memory decline after that onset. Inclusion of education did not significantly add to the fit of the model beyond the effect of cognitive activities. CONCLUSIONS: Our findings show that late life cognitive activities influence cognitive reserve independently of education. The effect of early life education on cognitive reserve may be mediated by cognitive activity later in life. Alternatively, early life education may be a determinant of cognitive reserve, and individuals with more education may choose to participate in cognitive activities without influencing reserve. Future studies should examine the efficacy of increasing participation in cognitive activities to prevent or delay dementia.

Evolutionary divergence of LFY function in the mustards Arabidopsis thaliana and Leavenworthia crassa.

LEAFY (LFY), a transcription factor involved in the regulation of flower development in Arabidopsis thaliana, has been identified as a candidate gene in the diversification of plant architecture in Brassicaceae. Previous research with Leavenworthia crassa, which produces solitary flowers in the axils of rosette leaves, has shown that the L. crassa LFY ortholog, LcrLFY, rescues most aspects of flower development in A. thaliana but showed two novel traits: flowers produced additional petals and inflorescences produced terminal flowers. In this paper, we explore the molecular mechanisms responsible for these novel phenotypes. We used microarray hybridizations to identify 32 genes differentially expressed between a transgenic LcrLFY line and a control transgenic LFY line. Of particular interest, TERMINAL FLOWER 1 (TFL1) transcripts were found at elevated levels in LcrLFY lines. To distinguish regulatory versus functional changes within the LcrLFY locus, reciprocal chimeric transgenes between LcrLFY and LFY were constructed. These lines implicate divergence of LcrLFY cis-regulation as the primary cause of both novel transgenic phenotypes but implicate divergence of LcrLFY protein function as the primary cause of elevated TFL1 levels. Taken together these results show that LcrLFY has diverged from A. thaliana in both the cis-regulatory and protein-coding regions and imply that molecular coevolution of LcrLFY and the L. crassa TFL1 ortholog, LcrTFL1, contributed to the evolution of rosette flowering.

Dementia incidence may increase more slowly after age 90: results from the Bronx Aging Study.

BACKGROUND: Dementia incidence increases dramatically from age 65 to age 85, with many studies reporting a doubling every 5 years. The incidence beyond age 85 is not established. OBJECTIVE: To estimate the incidence of dementia as a function of age, with a particular focus on persons aged 85 and over. METHODS: The Bronx Aging Study began in 1980 with 488 healthy, nondemented community-dwelling individuals, age 75 to 85. Persons in the study received clinical examinations and cognitive testing approximately every 12 months until death or loss to follow-up. The diagnosis of dementia was made using Diagnostic and Statistical Manual of Mental Disorders-III-R at diagnostic case conferences. Dementia incidence rates were calculated for 5-year age bands using person-time of follow-up as the denominator. RESULTS: The relative incidence rate ratios of dementia for age 80 to 84 vs 75 to 79 was 2.32 (95% CI 1.23 to 4.37), the relative rate for age 85 to 89 vs 80 to 84 was 1.89 (95% CI 1.26 to 2.83), the relative rate for age 90 to 94 vs 85 to 89 was 1.49 (95% CI 0.86 to 2.58), while the relative rate for age 95 to 99 vs 90 to 94 was 1.31 (95% CI 0.38 to 4.46). Similar results were seen for men and women considered separately. Had the rate of increase from age 75 to 89 continued into the 90s, the study would have had 73% power to detect a significant difference between the rates for age 90 to 94 and 85 to 89 given the amount of observed follow-up time. CONCLUSIONS: Whereas dementia incidence continues to increase beyond age 85, the rate of increase appears to slow relative to that of 65- to 85-year-olds. These results suggest that dementia in the oldest old might be related not to the aging process itself but with age-associated risk factors.

Understanding Ageing. An evaluation of research designs for assessing the interdependence of ageing-related changes.

BACKGROUND: Cross-sectional studies of samples varying widely in age have found moderate to high levels of shared age-related variance among measures of cognitive and physiological capabilities, leading researchers to posit common factors or common causal influences for diverse age-related phenomenon. OBJECTIVE: The influence of population average changes with age on cross-sectional estimates of association has not been widely appreciated in developmental and ageing research. Covariances among age-related variables in cross-sectional studies are highly confounded in regards to inferences about associations among rates of change within individuals since covariances can result from a number of sources including average population age-related differences (fixed age effects) in addition to initial individual differences and individual differences in rates of ageing (random age effects). Analysis of narrow age-cohort samples may provide a superior analytical basis for testing hypotheses regarding associations between rates of change in cross-sectional studies. CONCLUSIONS: The use of age-heterogeneous cross-sectional designs for evaluating interdependence of ageing-related processes is discouraged since associations will not necessarily reflect individual-level correlated rates of change. Typical cross-sectional studies do not provide sufficient evidence for the interdependence of ageing-related changes and should not serve as the basis for theories and hypotheses of ageing. Reanalyzing existing cross-sectional studies using a sequential narrow-age cohort approach provides a useful alternative for evaluating associations between ageing-related changes. Longitudinal designs, however, provide a much stronger basis for inference regarding associations between rates of ageing within individuals.

Lexical emotional expression across the life span: quantitative and qualitative analyses of word list generation tasks.

The current study examined the effects of age and gender on emotional and nonemotional expression using an experimental word list generation (WLG) task (also referred to in the literature as verbal fluency) from the New York Emotion Battery (Borod, Welkowitz, & Obler, 1992). Subjects were 28 young ( M = 29.6 years), 28 middle-aged (M = 49.8 years), and 28 older (M = 69.9 years) healthy adults. The WLG task consists of 8 emotional (E; 3 positive and 5 negative) and 8 nonemotional (NE) categories. We developed and present here a detailed word error-type analysis that was used to evaluate the lexical output. In this study, both quantitative (amount of output and error-types) and qualitative (accuracy and intensity) analyses were used. While subjects produced more nonemotional than emotional words and more positive than negative words, the amount of error-free output and the number of errors did not change with age. An age group by error-type interaction indicated that older adults, especially men, produced more repetition errors than younger adults. The error-free output was subsequently rated for accuracy and emotional intensity. The rating data revealed that older women's overall lexical output was less accurate than that produced by younger women. Also, negative emotional words were more accurate and intense than positive emotional words. The procedures described here have implications for research assessing word list generation and emotional expression in clinical populations.

Assessment of myocardial perfusion and viability with stress Tc-99m-MIBI SPECT before surgical revascularisation. Correlation with postoperative perfusion improvement.

BACKGROUND: The immediate result of successful revascularisation of the myocardium is the improvement of perfusion (and in patients with depressed ventricular function, functional recovery is expected as an effect of coronary flow improvement). The main goal of the work was to assess the value of myocardial stress-rest MIBI perfusion scintigraphy in predicting myocardial perfusion state measured early (< 5 months) after CABG. MATERIAL AND METHODS: Forty-three patients (39 males, mean age 52 +/- 9 years) with chronic coronary artery disease underwent prerevascularisation and postrevascularisation stress-rest Tc-99m-MIBI SPECT studies. Eighty-one percent of patients had a history of myocardial infarction, the number of stenosed main coronary arteries was 2.3 +/- 0.6 per patient, and the left ventricle ejection fraction was 18-70% (mean 46 +/- 14%). Preoperative perfusion defects were considered as small, medium or severe (depending upon stress uptake deficiency) and as transient or persistent (depending upon uptake improvement in rest). Changes in perfusion defects (improvement, lack of changes or deterioration) were evaluated very early after CABG (mean 31 +/- 12 days) in all patients and additionally about 3 months later (mean 119 +/- 17 days after CABG) in 36 patients. RESULTS: In transient perfusion defects, the probability of early postoperative perfusion improvement was 80% (in small defects: 89%, CI(0,95) = 80-94%) and was significantly higher than in small persistent defects (51%) and than in medium-and-severe persistent defects (21%). In medium-and-severe persistent defects, the lack of changes in perfusion was observed in 76% of defects (in severe defects: 81%, CI(0,95)= 69-91%) and was significantly higher than in small persistent defects (37%), than in medium-and-severe transient defects (17%), and than in small transient defects (4%). The probability of later postoperative perfusion improvement was 78% in transient perfusion defects (in small defects: 85%, CI(0,95)=74-92%) and was significantly higher than in small, medium, and severe persistent defects (28%). In medium-and-severe persistent defects, the lack of changes in perfusion was observed in 71% of defects (in severe defects: 81%, CI(0,95)=66-91%) and was significantly higher than in small persistent defects (40%), and than in severe, medium, and small transient defects (11%). CONCLUSIONS: 1. The result of preoperative stress-rest Tc-99m-MIBI SPECT myocardial perfusion study is an exact predictor of the state of perfusion measured early (< 5 months) after CABG; the postoperative regional perfusion improvement is most dependent upon reversibility and also upon severity of stress defect. 2. In small persistent defects, changes in perfusion are different than in other types of defects - so they should not be considered together with transient defects (as "viable") or with persistent defects (as "nonviable"). 3. Preoperative viability assessment on the basis of Tc-99m-MIBI study performed solely in rest is unjustified: at the similar perfusion defect at rest, the presence of even minimal inducible ischaemia is associated with increased probability of perfusion improvement after CABG.

Estimation of bivariate measurements having different change points, with application to cognitive ageing.

Longitudinal studies of ageing make repeated observations of multiple measurements on each subject. Change point models are often used to model longitudinal data. We demonstrate the use of Bayesian and profile likelihood methods to simultaneously estimate different change points in the longitudinal course of two different measurements of cognitive function in subjects in the Bronx Aging Study who developed Alzheimer's disease (AD). Analyses show that accelerated memory decline, as measured by Buschke Selective Reminding, begins between seven and eight years before diagnosis of AD, while decline in performance on speeded tasks as measured by WAIS Performance IQ begins slightly more than two years before diagnosis, significantly after the decline in memory.

Cognitive performance in surgically menopausal women on estrogen.

Estrogen replacement therapy (ERT) may help maintain normal cognitive function. Nondemented surgically menopausal women on ERT (n = 10) enrolled in a longitudinal aging study performed better than age- and education-matched control subjects (n = 25) on selected tests of verbal memory and constructional ability. These results suggest that ERT initiated soon after surgical menopause can have long-term neuroprotective effects in cognitively intact women.

Microbial genome analyses: comparative transport capabilities in eighteen prokaryotes.

Here, we present a comprehensive analysis of solute transport systems encoded within the completely sequenced genomes of 18 prokaryotic organisms. These organisms include four Gram-positive bacteria, seven Gram-negative bacteria, two spirochetes, one cyanobacterium and four archaea. Membrane proteins are analyzed in terms of putative membrane topology, and the recognized transport systems are classified into 76 families, including four families of channel proteins, four families of primary carriers, 54 families of secondary carriers, six families of group translocators, and eight unclassified families. These families are analyzed in terms of the paralogous and orthologous relationships of their protein members, the substrate specificities of their constituent transporters and their distributions in each of the 18 organisms studied. The families vary from large superfamilies with hundreds of represented members, to small families with only one or a few members. The mode of transport generally correlates with the primary mechanism of energy generation, and the numbers of secondary transporters relative to primary transporters are roughly proportional to the total numbers of primary H(+) and Na(+) pumps in the cell. The phosphotransferase system is less prevalent in the analyzed bacteria than previously thought (only six of 14 bacteria transport sugars via this system) and is completely lacking in archaea and eukaryotes. Escherichia coli is shown to be exceptionally broad in its transport capabilities and therefore, at a membrane transport level, does not appear representative of the bacteria thus far sequenced. Archaea and spirochetes exhibit fewer proteins with multiple transmembrane segments and fewer net transporters than most bacteria. These results provide insight into the relevance of transport to the overall physiology of prokaryotes.

A change point model for estimating the onset of cognitive decline in preclinical Alzheimer's disease.

Dementia is characterized by accelerated cognitive decline before and after diagnosis as compared to normal ageing. Determining the time at which that rate of decline begins to accelerate in persons who will develop dementia is important both in describing the natural history of the disease process and in identifying the optimal time window for which treatments might be useful. We model that time at which the rate of decline begins to accelerate in persons who develop dementia relative to those who do not by using a change point in a mixed linear model. A profile likelihood method is proposed to draw inferences about the change point. The method is applied to data from the Bronx Ageing Study, a cohort study of 488 initially non-demented community-dwelling elderly individuals who have been examined at approximately 12-month intervals over 15 years. Cognitive function was measured using the Buschke Selective Reminding test, a memory test with high reliability and known discriminative validity for detecting dementia. We found that the rate of cognitive decline as measured by this test in this cohort increases on average 5.1 years before the diagnosis of dementia.

The sensitivity and specificity of self-reported symptoms in individuals with traumatic brain injury.

In this study, self-reported symptoms (cognitive, physical, behavioural/affective) from the TIRR Symptom Checklist are compared across six panels: 135 individuals with mild TBI, 275 with moderate/severe TBI, 287 with no disability, 104 with spinal cord injury, 197 who are HIV positive and 107 who had undergone liver transplantation. Participants with TBI and SCI were at least 1 year post-injury. Individuals with TBI reported significantly more symptoms than other panels. Symptom reports in the TBI panels were independent of demographic variables (gender, education, income, ethnicity, age), as well as time since injury and depression. Five of the 67 symptoms were found to be sensitive/specific to TBI in general; 25 symptoms were sensitive/specific to mild TBI (23 were cognitive, one physical and one behavioural/affective). Implications of these results in terms of current debates about the 'reality' of symptom reports in individuals with mild TBI are discussed, as well as implications for using symptom checklists for TBI screening.

Verbal pragmatics following unilateral stroke: emotional content and valence.

Verbal pragmatic aspects of discourse production were examined in 16 right brain-damaged (RBD), 16 left brain-damaged (LBD), and 16 normal control right-handed adults. The facilitation effect of emotional content, valence hypothesis, and relationship between pragmatics and emotion were evaluated. Participants produced monologues while recollecting emotional and nonemotional experiences. Transcribed monologues were rated for appropriateness on 6 pragmatic features: conciseness, lexical selection, quantity, relevancy, specificity, and topic maintenance. Overall, brain-damaged groups were rated as significantly less appropriate than normals. Consistent with the facilitation effect, emotional content enhanced pragmatic performance of LBD aphasic participants yet suppressed performance of RBD participants. Contrary to the valence hypothesis, RBD participants were more impaired for positive emotions and LBD participants for negative emotions. Pragmatic appropriateness was not strongly correlated with a measure of emotional intensity.

Evaluation of the impact of transmyocardial laser (CO2) revascularisation on myocardial perfusion--6-months observations.

BACKGROUND: Transmyocardial laser revascularisation (TMLR) is a relatively new surgical approach to symptomatic coronary artery disease patients otherwise inoperable by classical revascularisation methods. Perfusion improvement after TMLR is considered as one possible mechanism causing alleviation of symptoms in a significant percentage of operated patiens. The goal of this work was to assess the history f myocardial perfusion during the first 6 month after sole TMLR operation. METHODS: TMLR was performed by using high-power (800 W) CO(2) laser. Tc-99m-Sestamibi single photon emission computed tomography (SPECT), both in rest and stress, was performed 4 times: before TMLR [SPECT-0], very early (mean: 3 weeks) after TMLR [SPECT-I], 3 months after TMLR [SPECT-II] and 6 months after TMLR [SPECT-III] in every patient. The group consisted of 25 patients, including 21 patients with previous myocardial infarctions. The patients subjected to the operation were those suffering from angina in spite of pharmacological therapy, with diffuse changes in the peripheral parts of coronary arteries, with left ventricle (LV) ejection fraction not lower than 0.30 and with at least one transient or small persistent defect in preoperative SPECT. Perfusion was assessed in 13 of 17 segments of the LV (after exclusion of 4 septal segments). Only a history of transient or small persistent perfusion defects ('viable' segments) detected in SPECT-0 is discussed. RESULTS: In comparison to SPECT-0: in SPECT-I perfusion did not change in 52% of segments, improved--in 31%, and deteriorated--in 17%: in SPECT-II perfusion did not change in 48% of segments, improved--in 34%, and deteriorated--in 18%; in SPECT-III perfusion did not change in 52%, improved--in 25%, and deteriorated--in 22% of segments. No significant difference in the number of segments with perfusion preservation, improvement or deterioration in comparison to SPECT-0 was found in SPECT-I,-II or III. In SPECT-II in comparison to SPECT-I, no changes in perfusion were found in 66% of segments, perfusion improved in 20% and deteriorated in 14%. In SPECT-III in comparison to SPECT-II, no changes in perfusion were found in 79% of segments, perfusion improved in 5% and deteriorated in 15%. CONCLUSIONS: Our evaluation of the history of segments with preoperatively transient or small persistent ('viable') defects indicates that during the first 6 months after TMLR: 1) perfusion is better than before the operation in about one third of the segments, and 20 in some of these segments there are dynamic perfusion changes (improvement or deterioration) from one to the next postoperative moment of observation.

[Pulmonary thrombendarterectomy in treatment of patients with chronic thromboembolic pulmonary hypertension]. / Trombendarterektomia tetnic plucnych w leczeniu chorych z nadcisnieniem plucnym w przebiegu przewleklej zatorowosci plucnej.

20 consecutive patients with thromboembolic pulmonary hypertension underwent pulmonary thromboendarterectomy. Mean pulmonary artery pressure decreased from mean 49.9 +/- 9.8 to 25.1 +/- 8.8 mm Hg (p < 0.0001), pulmonary vascular resistance decreased from mean 5.58 +/- 2.58 to 1.62 +/- 0.79 mm Hg/l*min-1 (p < 0.0001) and cardiac output increased from 3.71 +/- 1.18 to 6.92 +/- 1.64 l/min. Sixteen patients had marked clinical improvement. Two patients died in early and 2 patients in late postoperative period due to unrelieved pulmonary hypertension and postoperative complications.

How strong is the evidence for mediational hypotheses of age-related memory loss? Commentary.

BACKGROUND: Luszcz and Bryan review research supporting three theories of age-related memory loss: the speed hypothesis, the executive function hypothesis, and the common cause hypothesis. OBJECTIVE: The aim of this commentary is to extend that review by encouraging consideration of the strength (or lack thereof) of the empirical evidence supporting theories of age-related memory loss. METHODS: Arguments are presented that call into the question the strength of the evidence that derives from cross-sectional analysis of individual difference sources of variance. RESULTS: Supporting evidence for mediational hypotheses of cognitive aging (1) derives from potentially ambiguous statistical techniques; (2) is based on untested assumptions about the between and within person sources of variance; (3) is not supported by longitudinal studies, and (4) relies heavily on arguments of parsimony. CONCLUSIONS: Existing evidence is not strong enough to grant any particular theory presumptive status. We concur with Luszcz and Bryan that supplementing the now popular individual differences research designs with alternative approaches would advance theory development and testing.

Psychometric aspects of verbal pragmatic ratings.

This study examined the psychometric aspects of a verbal pragmatic rating scale. The scale contained six pragmatic features (i.e., Conciseness, Lexical Selection, Quantity, Relevancy, Specificity, and Topic Maintenance) based on Grice's cooperative principles. Fifteen right brain-damaged (RBD), 15 left brain-damaged (LBD), and 16 healthy normal control (NC) right-handed adult participants produced narratives while recollecting emotional and nonemotional experiences. Naive raters evaluated each pragmatic feature for appropriateness on a 5-point Likert scale. When reliability was examined, the overall internal consistency of the pragmatic scale was extremely high (alpha =.96). Factor analysis was conducted to examine the theoretical relations among the six pragmatic features. Three meaningful factors involving discourse content, conceptual unity, and parsimony were identified. Findings are discussed in light of Grice's model and the construct validity of the scale.

Cross-sectional and longitudinal relationships among age, cognition, and processing speed.

Cross-sectional and longitudinal age effects on cognitive function were examined in 302 older adults followed longitudinally. Processing speed was related to cognitive performance at cross-section, and change in speed predicted within-person longitudinal cognitive decline. Statistical control of processing speed greatly reduced cross-sectional age effects but did not attenuate longitudinal aging effects. This difference in processing speed's ability to account for cross-sectional and longitudinal age effects is discussed in the context of theories of cognitive aging and methodological and statistical issues pertaining to the cross-sectional and longitudinal study of cognitive aging.

Cognitive processing speed in Lyme disease.

OBJECTIVE: The goal of this study was to more precisely define the nature of the cognitive processing deficits in the patients with Lyme disease. BACKGROUND: Lyme disease has been associated with cognitive disturbances. METHOD: Sixteen patients who met the Centers for Disease Control's case definition for Lyme disease and 15 age- and education-matched control subjects completed two computerized assessments. The first was a matching procedure that assessed perceptual/motor speed. The second task was an alphabet-arithmetic (AA) test that measured the speed of mental arithmetic. On the matching task, subjects judged as true or false simple identity equations (e.g., B + 0 = B). On the AA task, subjects indicated the veracity of equations of the same form as those of the matching task but which required mental arithmetic (e.g., A + 3 = D). The use of this paradigm permits sensory or motor slowing to be distinguished from slowed cognitive processing speed. Also, the tests do not involve automated or overlearned responses. RESULTS: Lyme disease patients and healthy controls did not differ in perceptual/motor speed. However, Lyme disease patients' response times were significantly longer than those of healthy controls during the AA task, demonstrating specific impairments in mental activation speed. CONCLUSIONS: These results suggest that Lyme disease patients show specific deficits when initiating a cognitive process. These impairments are independent of sensory, perceptual, or motor deficits.