Neuropsychological and neuroradiological correlates in Huntington's disease

Using the LASSI-L to Detect Robust Interference Effects in Premanifest Huntington Disease

BACKGROUND

Diagnosis of manifest Huntington disease (HD) is based primarily on motor symptoms, but premanifest HD (preHD) is often associated with subtle cognitive decline. The Loewenstein-Acevedo Scales for Semantic Interference and Learning (LASSI-L) is a validated verbal learning test that can be used to detect early cognitive decline.

OBJECTIVE

To determine the utility of the LASSI-L for detecting early cognitive decline in individuals with preHD and to compare the results of the LASSI-L with those of commonly used neuropsychological tests in HD.

METHOD

We administered the LASSI-L to 13 individuals with preHD and 13 healthy controls matched for age, sex, and education as part of a longitudinal study of disease progression. For comparison purposes, we administered the Mini-Mental State Examination; Stroop Color and Word Test; Symbol Digit Modalities Test; Trail-Making Test, Parts A and B; and category fluency (animals) task.

RESULTS

Five of the seven sections on the LASSI-L captured group differences: Proactive Semantic Interference (PSI; P < 0.001), Failure to Recover From PSI ( P = 0.038), Retroactive Semantic Interference (RSI; P = 0.013), Delayed Recall ( P < 0.001), and B1 Cued Recall Intrusions ( P = 0.036). Using a false discovery rate of <0.05, PSI, RSI, and Delayed Recall remained significant.

CONCLUSION

The LASSI-L is a sensitive instrument for detecting early interference effects in individuals with preHD that outperforms commonly used neuropsychological tests. The LASSI-L could be a useful addition to clinical and research protocols involving individuals with preHD.

Inflammatory markers are associated with psychomotor slowing in patients with schizophrenia compared to healthy controls

Patients with schizophrenia exhibit psychomotor deficits that are associated with poor functional outcomes. One pathway that may be associated with psychomotor slowing is inflammation. Inflammatory markers have been shown to be elevated in patients with schizophrenia and are associated with psychomotor deficits in both animal and human studies. Forty-three patients with schizophrenia and 29 healthy controls were recruited and underwent a battery of psychomotor tasks. The following immune measures in peripheral blood were assayed: IL-6, IL-1 beta, IL-10, TNF, MCP-1, IL-6sr, IL-1RA, and TNFR2. Generalized linear models were used to determine which immune markers, in addition to their interaction with diagnosis, were associated with performance on the psychomotor tasks. As expected, patients with schizophrenia demonstrated slower performance compared with healthy controls on the finger tapping test (FTT, tested on dominant and non-dominant hands), trail making test (TMT), and symbol coding test (SC). Interactive effects with diagnosis were found for TNF, IL-10, IL-6sr, and TNFR2 for the FTT (dominant), IL-10 and IL-6sr for FTT (non-dominant), TNF and IL-10 for TMT and TNF, IL-10, IL-6sr, TNFR2, and IL-1RA for SC. The results of this study provide evidence that peripheral inflammatory markers contribute to psychomotor slowing in patients with schizophrenia. These data are consistent with a growing literature, demonstrating that inflammation may target the basal ganglia to contribute to psychomotor deficits as is seen in other psychiatric disorders such as depression. These data also indicate that psychomotor speed may be a relevant construct to target in studies of the immune system in schizophrenia.

Neuropsychological Functioning following Fetal Striatal Transplantation in Huntington's Chorea: Three Case Presentations

Neurotransplantation has been proposed as a potential treatment for the neurodegenerative disorder of Huntington's disease (HD), which currently has no effective therapy. While patients with Parkinson's disease have received neurotransplantation, until recently no HD patients have undergone transplantation for HD with standardized evaluations of their progress following surgery. The current report presents the cognitive changes in three patients with HD who underwent bilateral transplantation of human fetal striatal tissue. As part of the pre- and postsurgical evaluation, all three patients were administered a neuropsychological battery sensitive to the cognitive effects of HD within 2 mo prior to surgery and at 4-6 mo following transplantation. Four to 6 mo subsequent to surgery, all patients demonstrated increased scores on some measures of cognitive functioning. However, the pattern of changes was not uniform across subjects. These findings suggest that fetal striatal transplantation may improve some of the cognitive symptoms associated with HD in the three reported patients.

Symbol Digit Modalities Test: Normative data for the Latin American Spanish speaking adult population

OBJECTIVE

To generate normative data on the Symbol Digit Modalities Test (SDMT) across 11 countries in Latin America, with country-specific adjustments for gender, age, and education, where appropriate.

METHOD

The sample consisted of 3,977 healthy adults who were recruited from Argentina, Bolivia, Chile, Cuba, El Salvador, Guatemala, Honduras, Mexico, Paraguay, Peru, and, Puerto Rico. Each subject was administered the SDMT as part of a larger neuropsychological battery. A standardized five-step statistical procedure was used to generate the norms.

RESULTS

The final multiple linear regression models explained 29-56% of the variance in SDMT scores. Although there were gender differences on the SDMT in Mexico, Honduras, Paraguay, and Guatemala, none of the four countries had an effect size greater than 0.3. As a result, gender-adjusted norms were not generated.

CONCLUSIONS

This is the first normative multicenter study conducted in Latin America to create norms for the SDMT; this study will have an impact on the future practice of neuropsychology throughout the global region.

Inflammatory markers are associated with decreased psychomotor speed in patients with major depressive disorder

Previous data have demonstrated that administration of inflammatory cytokines or their inducers leads to altered basal ganglia function associated with reduced psychomotor speed. Decreased psychomotor speed, referred to clinically as psychomotor retardation, is a cardinal symptom of major depressive disorder (MDD) and has been associated with poor antidepressant treatment response. We therefore examined the association between plasma inflammatory markers and psychomotor speed in ninety-three un-medicated patients with MDD. Psychomotor speed was assessed by a range of neuropsychological tests from purely motor tasks (e.g. movement latency and finger tapping) to those that involved motor activity with increasing cognitive demand and cortical participation (e.g. Trails A and Digit Symbol Substitution Task (DSST)). Linear regression analyses were performed to determine the relationship of inflammatory markers and psychomotor task performance controlling for age, race, sex, education, body mass index, and severity of depression. MDD patients exhibited decreased psychomotor speed on all tasks relative to normative standards. Increased IL-6 was associated with decreased performance on simple and choice movement time tasks, whereas MCP-1 was associated with decreased performance on the finger tapping task and DSST. IL-10 was associated with increased performance on the DSST. In an exploratory principle component analysis including all psychomotor tasks, IL-6 was associated with the psychomotor speed factor. Taken together, the data indicate that a peripheral inflammatory profile including increased IL-6 and MCP-1 is consistently associated with psychomotor speed in MDD. These data are consistent with data demonstrating that inflammation can affect basal ganglia function, and indicate that psychomotor speed may be a viable outcome variable for anti-inflammatory therapies in depression and other neuropsychiatric disorders with increased inflammation.

Assessing impairment of executive function and psychomotor speed in premanifest and manifest Huntington's disease gene-expansion carriers

Executive functions (EF) and psychomotor speed (PMS) has been widely studied in Huntington's disease (HD). Most studies have focused on finding markers of disease progression by comparing group means at different disease stages. Our aim was to investigate performances on nine measures of EF and PMS in a group of premanifest and manifest HD-gene expansion carriers and to investigate which measures were most sensitive for assessment of individual patients by analyzing frequencies of impaired performances relative to healthy controls. We recruited HD gene-expansion carriers, 48 manifest and 50 premanifest and as controls 39 healthy gene-expansion negative individuals. All participants underwent neurological examination and neuropsychological testing with nine cognitive measures. The frequency of impairment was investigated using cutoff scores. In group comparisons the manifest HD gene-expansion carriers scored significantly worse than controls on all tests and in classification of individual scores the majority of scores were classified as probably impaired (10th percentile) or impaired (5th percentile) with Symbol Digit Modalities Test (SDMT) being the most frequently impaired. Group comparisons of premanifest HD gene-expansion carriers and healthy controls showed significant differences on SDMT and Alternating fluency tests. Nevertheless the frequencies of probably impaired and impaired scores on individual tests were markedly higher for Alternating and Lexical fluency tests than for SDMT. We found distinct group differences in frequency of impairment on measures of EF and PMS in manifest and premanifest HD gene-expansion carriers. Our results indicate to what degree these measures can be expected to be clinically impaired.

Regional atrophy associated with cognitive and motor function in prodromal Huntington disease

BACKGROUND

Neuroimaging studies suggest that volumetric MRI measures of specific brain structures may serve as excellent biomarkers in future clinical trials of Huntington disease (HD).

OBJECTIVE

Demonstration of the clinical significance of these measures is an important step in determining their appropriateness as potential outcome measures.

METHODS

Measures of gray- and white-matter lobular volumes and subcortical volumes (caudate, putamen, globus pallidus, thalamus, nucleus accumbens, hippocampus) were obtained from MRI scans of 516 individuals who tested positive for the HD gene expansion, but were not yet exhibiting signs or symptoms severe enough to warrant diagnosis ("pre-HD"). MRI volumes (corrected for intracranial volume) were correlated with cognitive, motor, psychiatric, and functional measures known to be sensitive to subtle changes in pre-HD.

RESULTS

Caudate, putamen, and globus pallidus volumes consistently correlated with cognitive and motor, but not psychiatric or functional measures in pre-HD. Volumes of white matter, nucleus accumbens, and thalamus, but not cortical gray matter, also correlated with some of the motor and cognitive measures.

CONCLUSIONS

Results of regression analyses suggest that volumes of basal ganglia structures contributed more highly to the prediction of most motor and cognitive variables than volumes of other brain regions. These results support the use of volumetric measures, especially of the basal ganglia, as outcome measures in future clinical trials in pre-HD. Results may also assist investigators in selecting the most appropriate measures for treatment trials that target specific clinical features or regions of neuropathology.

Cognitive reserve and brain reserve in prodromal Huntington's disease

Huntington disease (HD) is associated with decline in cognition and progressive morphological changes in brain structures. Cognitive reserve may represent a mechanism by which disease-related decline may be delayed or slowed. The current study examined the relationship between cognitive reserve and longitudinal change in cognitive functioning and brain volumes among prodromal (gene expansion-positive) HD individuals. Participants were genetically confirmed individuals with prodromal HD enrolled in the PREDICT-HD study. Cognitive reserve was computed as the composite of performance on a lexical task estimating premorbid intellectual level, occupational status, and years of education. Linear mixed effects regression (LMER) was used to examine longitudinal changes on four cognitive measures and three brain volumes over approximately 6 years. Higher cognitive reserve was significantly associated with a slower rate of change on one cognitive measure (Trail Making Test, Part B) and slower rate of volume loss in two brain structures (caudate, putamen) for those estimated to be closest to motor disease onset. This relationship was not observed among those estimated to be further from motor disease onset. Our findings demonstrate a relationship between cognitive reserve and both a measure of executive functioning and integrity of certain brain structures in prodromal HD individuals.

Striatal volume contributes to the prediction of onset of Huntington disease in incident cases

BACKGROUND

Previous neuroimaging research indicates that brain atrophy in Huntington disease (HD) begins many years before movement abnormalities become severe enough to warrant diagnosis. Most clinical trials being planned for individuals in the prediagnostic stage of HD propose to use delay of disease onset as the primary outcome measure. Although formulas have been developed based on age and CAG repeat length, to predict when HD motor onset will occur, it would be useful to have additional measures that can improve the accuracy of prediction of disease onset.

METHODS

The current study examined magnetic resonance imaging (MRI) measures of striatum and white matter volume in 85 individuals prospectively followed from pre-HD stage through diagnosable motor onset (incident cases) and 85 individuals individually matched with incident cases on CAG repeat length, sex, and age, who were not diagnosed with HD during the course of the study.

RESULTS

Volumes of striatum and white matter were significantly smaller in individuals who would be diagnosed 1 to 4 years following the initial MRI scan, compared with those who would remain in the pre-HD stage. Putamen volume was the measure that best distinguished between the two groups.

CONCLUSIONS

Results suggest that MRI volumetric measures may be helpful in selecting individuals for future clinical trials in pre-HD where HD motor onset is the primary outcome measure. In planning for multisite clinical trials in pre-HD, investigators may also want to consider using more objective measures, such as MRI volumes, in addition to onset of diagnosable movement disorder, as major outcome measures.

Memory and strategic processing in first-degree relatives of obsessive compulsive patients

BACKGROUND

The same executive dysfunctions and alterations in neuroimaging tests (both functional and structural) have been found in obsessive-compulsive patients and their first-degree relatives. These neurobiological findings are considered to be intermediate markers of the disease. The aim of our study was to assess verbal and non-verbal memory in unaffected first-degree relatives, in order to determine whether these neuropsychological functions constitute a new cognitive marker for obsessive-compulsive disorder (OCD).

METHOD

Recall and use of organizational strategies in verbal and non-verbal memory tasks were measured in 25 obsessive-compulsive patients, 25 unaffected first-degree relatives and 25 healthy volunteers.

RESULTS

First-degree relatives and healthy volunteers did not show differences on most measures of verbal memory. However, during the recall and processing of non-verbal information, deficits were found in first-degree relatives and patients compared with healthy volunteers.

CONCLUSIONS

The presence of the same deficits in the execution of non-verbal memory tasks in OCD patients and unaffected first-degree relatives suggests the influence of certain genetic and/or familial factors on this cognitive function in OCD and supports the hypothesis that deficits in non-verbal memory tasks could be considered as cognitive markers of the disorder.

Cognitive and functional decline in Huntington's disease: dementia criteria revisited

The importance of designating criteria for diagnosing dementia lies in its implications for clinical treatment, research, caregiving, and decision-making. Dementia diagnosis in Huntington's disease (HD) is often based on criteria developed for Alzheimer's disease requiring memory loss. However, it is likely that other cognitive deficits contribute to functional impairment in HD before memory declines. The goal is to identify cognitive deficits that contribute to functional impairment to support dementia criteria that reflect HD neuropathology. Eighty-four HD mutation-positive subjects completed neuropsychological tests and the Unified Huntington's Disease Rating Scale Functional Independence Scale (FIS). Functional impairment was defined as 80 or below on the FIS. Speed of processing, initiation, and attention measures accounted for 70.0% of the variance in FIS ratings (linear regression) and correctly classified 91.7% of subjects as functionally impaired or intact (logistic regression). Measures of memory, motor impairment except dysarthria, neuroleptic use, and depressed mood did not improve prediction. A definition of HD dementia that includes cognitive impairment in at least two areas of cognition but does not require a memory deficit, in the context of impaired functional abilities and a deteriorating course, more accurately reflects HD neuropathology and could lead to improved research methods and patient care.

Early Detection of Huntington Disease

Huntington disease (HD) is a devastating illness, although its autosomal dominant genetic transmission allows a unique opportunity to study apparently healthy individuals before manifest disease. Attempts to study early disease are not unique in neurology (e.g., Mild Cognitive Impairment, Vascular Cognitive Impairment), but studying otherwise-healthy appearing individuals who will go on with nearly 99% certainty to manifest the symptoms of brain disease does provide distinct but valuable information about the true natural history of the disease. The field has witnessed an explosion of research examining possible early indicators of HD during what is now referred to as the "prodrome" of HD. A NIH study in its ninth year (PREDICT-HD) has offered a glimpse into the transition from an apparently healthy state to an obviously diseased state, and can serve as a model for many other genetic diseases, both neurological and non-neurological.

Giant tumefactive perivascular spaces manifesting as chorea bilaterally

Virchow-Robin (VR) spaces or perivascular spaces (PVSs) of the brain are pial-lined interstitial fluid-filled structures that accompany penetrating arteries and arterioles for a variable distance as they descend into the cerebral substance. VR spaces can be identified on magnetic resonance (MR) images obtained in patients of all ages in many areas of the brain. Infrequently, these become remarkably enlarged, and can assume configurations that may be mistaken for a more clinically significant disease, such as a cystic neoplasm or parasitic infections like cysticercosis. We report the first MR imaging description of a case of giant tumefactive (PVSs) manifesting as chorea bilaterally.

Functional imaging in Huntington's disease

Huntington's disease (HD) is a genetic brain disease characterized by loss of capacity in movement control, cognition, and emotional regulation over a period of about 30 years. Since it is well established that clinical impairments and brain atrophy can be detected decades prior to receiving a clinical diagnosis, functional neuroimaging efforts have gained momentum in HD research. In most brain disorders, there is accumulating evidence that the clinical manifestations of disease do not simply depend on the extent of tissue loss, but represent a complex balance among neuronal dysfunction, tissue repair, and circuitry reorganization. Based upon this premise, functional neuroimaging modalities may be more sensitive to the earliest changes in HD than are structural imaging approaches. For this review, PET and fMRI studies conducted in HD samples were summarized. Strengths and limitations of the utilization of functional imaging in HD are discussed and recommendations are offered to facilitate future research endeavors.

Basal ganglia volume and clinical correlates in 'preclinical' Huntington's disease

OBJECTIVE

To establish differences in basal ganglia and thalamic volume between preclinical carriers and non-carriers of the Huntington's disease (HD) gene and to link the volume to motor, cognitive and behavioural characteristics in carriers.

METHODS

Sixteen HD gene carriers without overt clinical motor signs and 14 non-gene carriers underwent clinical evaluation and a MRI scan. Volumes of the caudate nucleus, putamen, gobus pallidus and thalamus were measured using T1-weighted MR images. Motor, cognitive and behavioural functioning was assessed using the Unified Huntington's Disease Rating Scale (UHDRS), cognitive testing and the Beck Depression Inventory (BDI-II).

RESULTS

Volumes of the caudate nucleus, putamen and globus pallidus were significantly smaller in carriers than in non-carriers while no differences between groups were found on clinical evaluation. In gene carriers smaller globus pallidus volume was associated with more motor abnormalities. A smaller putamen volume correlated significantly with worse psychomotor function on the Symbol Digit Modalities Task and the Trail Making Test B.

CONCLUSIONS

In line with previous research we demonstrated that basal ganglia abnormalities precede overt disease manifestation of HD. Besides we showed that smaller basal ganglia volumes are related to subtle motor abnormalities and worse psychomotor performance in gene carriers without clinical diagnosis. Motor and psychomotor measures may be suitable clinical markers in future neuroprotective trials when combined with volumetric imaging.

Assessment of simple movements reflects impairment in Huntington's disease

Clinical rating, caudate atrophy, disturbed movement performance, neuropsychological testing, and age-related genetic disease load (CAG index) are tools that reflect impairment after onset of Huntington's disease (HD). Objectives were to compare scored HD symptoms, results of neuropsychological testing and of instrumental measurement of simple motion sequences, assess caudate atrophy and CAG index, and investigate their relation to each other in 131 subjects of various HD stages. Caudate atrophy and CAG index significantly increased in advanced HD patients. Motor test results significantly differed between HD patients and 49 controls, but not between HD gene carriers and controls. Instrumental test outcomes, scored HD intensity, caudate atrophy, and CAG index significantly correlated to each other. Neuropsychological testing, which we only performed in the HD gene carriers and the previously untreated HD patients, reflected the early appearance of HD symptoms and correlated with the motor test results. Results of our applied instrumental tool measure impaired movement performance, which is not specific for HD, but reflects the various methods assessed and the slowly evolving symptoms of the degenerative process in HD.

Diffusion-weighted imaging in Huntington's disease

Huntington's disease (HD) is an autosomal dominant progressive neurodegenerative disorder that results from an expanded trinucleotide (CAG) repeat on the huntingtin gene. Neurodegeneration in HD affects most prominently the basal ganglia. Therefore, diffusivity was obtained in the basal ganglia and thalamus of 29 patients with early HD and 27 healthy volunteers by means of the trace of the diffusion tensor (Trace(D)). Putaminal, caudate, pallidal, and thalamic Trace(D) values were increased in patients with HD compared with controls. Increased diffusivity in the putamen and caudate nucleus correlated with global functional impairment, CAG repeat length, as well as bicaudate ratio. Diffusion-weighted imaging appears to be a promising surrogate marker for disease severity in HD. Sensitivity to change remains to be established longitudinally.

Executive function correlates with walking speed in older persons: the InCHIANTI study

OBJECTIVES

To study the association between performance on psychological tests of executive function and performance on lower extremity tasks with different attentional demands in a large sample of nondemented, older adults.

DESIGN

Cross-sectional study.

SETTING

Community-based.

PARTICIPANTS

Nine hundred twenty-six persons aged 65 and older, without dementia, stroke, parkinsonism, visual impairment, or current treatment with neuroleptics, enrolled in a large epidemiological study.

MEASUREMENTS

Trail Making Test (TMT) parts A and B and two performance-based measures of lower extremity function that require different executive/attentional-demanding skills: walking speed on a 4-m course at usual pace and walking speed on a 7-m obstacle course at fast pace. A difference score (Delta TMT), obtained by subtracting time to perform part A from time to perform part B of the TMT, was used as an indicator of executive function. Based on Delta TMT, subjects were divided into poor performance, intermediate performance, and good performance.

RESULTS

After adjustment, no association between Delta TMT and 4-m course usual-pace walking speed was found. Participants with poor Delta TMT and with intermediate Delta TMT performance were more likely to be in the lowest tertile for 7-m obstacle course walking speed.

CONCLUSION

In nondemented older persons, executive function is independently associated with tasks of lower extremity function that require high attentional demand.

Cognitive changes in patients with Huntington's disease (HD) and asymptomatic carriers of the HD mutation--a longitudinal follow-up study

OBJECTIVE

Objective information about the onset and progression of cognitive impairment in Huntington's disease (HD) is very important in the light of appropriate outcome measures when conducting clinical trials. Therefore, we evaluated the progression of cognitive functions in HD patients and asymptomatic carriers of the HD mutation (AC) over a 2.5-year period. We also sought to detect the earliest markers of cognitive impairment in AC.

METHODS

A prospective study comparing HD patients, clinically asymptomatic HD mutation-carriers (AC) and non-carriers (NC). These groups were examined three times during a period of 2.5 years. At baseline the study sample consisted of 49 subjects. Forty-two subjects (19 HD patients, 12 AC and 11 NC) completed three assessments. A battery of neuropsychological tests measuring intelligence, attention, memory, language, visuospatial perception, and executive functions was performed.

RESULTS

The performance of HD patients deteriorated on the following cognitive tests: Symbol Digit Modalities Test (SDMT), Stroop Colour and Word, Boston Naming Test (BNT), Object and Space Perception and Trail Making Test-B. Longitudinal comparison of AC and NC revealed that performances on SDMT, Block Span, Digit Span Backwards, Hopkins Verbal Learning Test (learning and delayed recall) and Conditional Associative Learning Test are impaired in AC.

CONCLUSIONS

Tasks measuring mainly attention, object and space perception and executive functions adequately assess the progression of HD disease. Other cognitive functions do not significantly deteriorate. Furthermore, problems in attention, working memory, verbal learning, verbal long-term memory and learning of random associations are the earliest cognitive manifestations in AC.

The development of a trial making test in young children: the TRAILS-P

Preschool children have a more limited verbal repertoire, less proficient manual skills, and more variable attention spans relative to those of school age, with comparatively few neuropsychological tasks available for use in this age range. A prototypic neuropsychological test, the Trail Making Test, was adapted for use with young children, the TRAILS-P, using a developmentally salient storybook format with colorful stimuli in differing conditions with varying executive demands. The TRAILS-P was administered to 103 normally developing preschoolers between 2 and 6 years of age; 30 of these children were retested within one month to determine test reliability. Correlations among latencies to complete each condition and condition errors generally were moderate to high, suggesting coherence in test content. There also was evidence for good test-retest reliability. Latency to complete the TRAILS-P conditions differed as a function of the interaction of condition type and age group. Although the youngest children generally took more time to complete all TRAILS-P conditions, 3-year-old children were disproportionately slow to complete the condition that required shifting between stamping stimuli of two classes, with distraction by the additional presence of irrelevant stimuli. In contrast, the number of errors differed only in the 5-year-olds relative to younger children. These findings suggest that executive abilities can be assessed adequately in young children when tasks are designed to take advantage of the developmentally unique features of the preschool period.

Predictive Testing for Huntington's Disease: How Does it Impact on Cognitive Performance?

The discovery of a polymorphic DNA marker for Huntington's Disease (HD) in 1983, and the specific gene responsible in 1993, led to predictive testing programmes out of which came research into whether or not cognitive impairment was present presymptomatically in those at risk for HD. The results of these studies have been conflicting and inconclusive. Methodoiogical limitations have probably contributed to the differing findings. The present study attempted to expand upon previous studies by analysing the data in a more comprehensive manner, and with additional control conditions. In this study, 26 individuals, at risk but presymptomatic, for HD were recruited from the Johannesburg Predictive Testing Programme and administered a battery of psychological tests prior to molecular analysis. Of this HD group, 11 were subsequently positive for the gene (the HD+ group) and 15 were negative (HD- group). A carefully chosen control group, (matched for age, sex, and education - Control Group 1) and a group of individuals experiencing a life threatening medical illness (without CNS involvement - Control Group 2) were administered the same battery of psychological tests. Four-way Analysis of Variance between the HD+, HD-, and Control groups was conducted to detect specific differences between the groups. The results indicated that the HD+ group showed mild impairment for declarative memory function. However, it would appear that undergoing the psychological evaluation itself impacted upon the test performance of both the HD+ and HD- groups.

Longitudinal study evaluating neuropsychological changes in so-called asymptomatic carriers of the Huntington's disease mutation after 1 year

OBJECTIVES

To determine (1) whether the battery of neuropsychological tests was sufficiently sensitive to find differences between symptomatic patients with Huntington's disease (HD) and clinically asymptomatic individuals carrying the HD gene (AGC) and individuals without the HD gene (NGC) and (2) whether increasing cognitive impairment is found in AGC as compared with NGC.

METHODS

A case-control, single-blind study comparing subjects with clinically manifest HD (n=21), AGC (n=12) or NGC (n=11) and a 1-year follow-up of AGC and NGC. Genotype for the HD gene was determined by molecular testing. A large battery of neuropsychological tests measuring several cognitive domains was performed.

RESULTS

On most neuropsychological tasks, HD patients perform significantly worse than AGC and NGC. At baseline and follow-up examination, compared with NGC, AGC had lower scores on the symbol digit modalities test. Scores on a block span task declined more rapidly among AGC than among NGC.

CONCLUSION

Cognitive impairments in HD patients are found when compared with clinically asymptomatic individuals carrying the HD mutation. Furthermore, our results suggest that subtle cognitive deficits are present in asymptomatic persons who have inherited the HD gene.

Neurobehavioral aspects of movement disorders

Cognitive, behavioral, affective, and psychiatric symptoms occur in almost all movement disorders. Diagnosis and management of movement disorders depends critically on an understanding of these neurobehavioral symptoms. This article reviews the neurobehavioral aspects of two representative movement disorders; Parkinson's disease and Huntington's disease.

Executive control functions in degenerative dementias: a comparative review

This paper reviews the literature concerning executive control impairments in degenerative dementias. The construct of executive control functioning is examined, as is the neuroanatomy of frontal-subcortical networks, believed to underlie executive function (EF) impairments. The pattern of EF impairments in Alzheimer's disease (AD) which affects temporal and parietal brain regions most severely is contrasted with observed executive dysfunctions in patients with dementias involving degeneration of primarily frontal and frontal-subcortical brain areas. EF impairments are present in each of these types of dementing illnesses. Although EF impairments are present in AD, they are less prominent than the memory disorder in the neuropsychological profile of the disease and tend to become more pronounced later in the course of the illness. In contrast, patients with frontal or frontal-subcortical dementia may demonstrate executive dysfunction, which occurs earlier in the disease progression and may be initially more severe.

Intuition: a social cognitive neuroscience approach

This review proposes that implicit learning processes are the cognitive substrate of social intuition. This hypothesis is supported by (a) the conceptual correspondence between implicit learning and social intuition (nonverbal communication) and (b) a review of relevant neuropsychological (Huntington's and Parkinson's disease), neuroimaging, neurophysiological, and neuroanatomical data. It is concluded that the caudate and putamen, in the basal ganglia, are central components of both intuition and implicit learning, supporting the proposed relationship. Parallel, but distinct, processes of judgment and action are demonstrated at each of the social, cognitive, and neural levels of analysis. Additionally, explicit attempts to learn a sequence can interfere with implicit learning. The possible relevance of the computations of the basal ganglia to emotional appraisal, automatic evaluation, script processing, and decision making are discussed.

Diagnosing dementia and normal aging: clinical relevance of brain ratios and cognitive performance in a Brazilian sample

The main objective of the present study was to evaluate the diagnostic value (clinical application) of brain measures and cognitive function. Alzheimer and multi-infarct patients (N = 30) and normal subjects over the age of 50 (N = 40) were submitted to a medical, neurological and cognitive investigation. The cognitive tests applied were Mini-Mental, word span, digit span, logical memory, spatial recognition span, Boston naming test, praxis, and calculation tests. The brain ratios calculated were the ventricle-brain, bifrontal, bicaudate, third ventricle, and suprasellar cistern measures. These data were obtained from a brain computer tomography scan, and the cutoff values from receiver operating characteristic curves. We analyzed the diagnostic parameters provided by these ratios and compared them to those obtained by cognitive evaluation. The sensitivity and specificity of cognitive tests were higher than brain measures, although dementia patients presented higher ratios, showing poorer cognitive performances than normal individuals. Normal controls over the age of 70 presented higher measures than younger groups, but similar cognitive performance. We found diffuse losses of tissue from the central nervous system related to distribution of cerebrospinal fluid in dementia patients. The likelihood of case identification by functional impairment was higher than when changes of the structure of the central nervous system were used. Cognitive evaluation still seems to be the best method to screen individuals from the community, especially for developing countries, where the cost of brain imaging precludes its use for screening and initial assessment of dementia.

Reduced basal ganglia blood flow and volume in pre-symptomatic, gene-tested persons at-risk for Huntington's disease

The aim of this study was to examine basal ganglia volumes and regional cerebral blood flow in asymptomatic subjects at-risk for Huntington's disease who had undergone genetic testing. We determined which measures were the best 'markers' for the presence of the mutation and for the onset of symptoms. Twenty subjects who were Huntington's disease gene mutation-positive and 24 Huntington's disease gene mutation-negative participants, all of whom had a parent with genetically confirmed Huntington's disease, and were therefore 50% at-risk for inheriting the Huntington's disease gene mutation, were included in the study. To evaluate basal ganglia structure and function, MRI and single photon emission computed tomography (SPECT) were used. Quantitative measures of regional volumes and relative measures of regional perfusion were calculated. SPECT and MRI scans were co-registered so that MRI anatomy could be used accurately to place SPECT regions. Estimated years-to-onset in the mutation-positive subjects was calculated based on a regression formula that included gene (CAG)(n) repeat length and parental age of onset. Changes in imaging measures in relation to estimated years-to-onset were assessed. The imaging measure that was most affected in mutation-positive subjects was putamen volume. This was also the measure that correlated most strongly with approaching onset. In subjects >/=7 years from estimated onset age, the putamen volume measures were similar to those of the mutation-negative subjects. However, in subjects </=6 years from estimated onset age, there were dramatic reductions in putamen volume, resulting in >90% discrimination from both the far-from-onset and the mutation-negative subjects. Caudate volume and bicaudate ratio also showed a significant decline in the close-to-onset subjects, although to a lesser degree than putamen volume reductions. Furthermore, SPECT basal ganglia perfusion deficits were observed in mutation-positive subjects. Imaging markers of neuropathological decline preceding clinical onset are important for assessing the effects of treatments aimed at slowing the course of Huntington's disease. The current study suggests that quantitative assessment of basal ganglia may provide a means to track early signs of decline in individuals with the Huntington's disease gene mutation prior to clinical onset.

Huntington disease: clinical, genetic, and social aspects

Huntington disease (HD) is a fascinating neurodegenerative disorder whose features straddle the boundaries of psychiatry, neurology, and genetics. The clinical symptoms of HD consist of a triad of motor, cognitive, and psychiatric/behavioral disturbances. In 1993, the HD Collaborative Research Group identified the gene and the mutation responsible for HD. HD was one of the first neurodegenerative disorders discovered to be caused by a novel mutational mechanism known as trinucleotide repeat expansion. Since then, HD has been the model for autosomal dominant neurogenetic disorders. The clinical, pathological, and genetic aspects of the disease are reviewed and some of the questions that remain to be answered by researchers of the 21st century are outlined.

Advances in the understanding of early Huntington's disease using the functional imaging techniques of PET and SPET

The functional imaging techniques of positron emission tomography (PET) and single photon emission tomography (SPET) have been used to study regional brain function in Huntington's disease (HD) in vivo. Reduced striatal glucose metabolism and dopamine receptor binding are evident in all symptomatic HD patients and in approximately 50% of asymptomatic adult mutation carriers. These characteristics correlate with clinical measures of disease severity. Reduced cortical glucose metabolism and dopamine receptor binding, together with reduced striatal and cortical opioid receptor binding, have also been demonstrated in symptomatic patients with HD. Repeat PET measures of striatal function have been used to monitor the progression of this disease objectively. In the future, functional imaging will provide a valuable way of assessing the efficacy of both fetal striatal cell implants and putative neuroprotective agents, such as nerve growth factors.

Neuropsychology of subcortical dementias

Subcortical dementias are a heterogeneous group of disorders that share primary pathology in subcortical structure and a characteristic pattern of neuropsychological impairment. This article describes the neurobiological and cognitive features of three prototypical subcortical dementias, Parkinson's disease, Huntington's disease, and progressive supranuclear palsy, concentrating of traits shared by disorders. Clinical features are also discussed, especially those which differentiate subcortical dementias from cortical dementias, such as Alzheimer's disease. The cortical-subcortical nomenclature has been criticized over the years, but it continues to provide an effective means of classifying dementia profiles in clinically and theoretically useful ways.

[Subcortical dementia]

Subcortical dementia, a concept introduced 20 years ago, is a clinical entity characterized by memory disorders, an impaired ability to manipulate acquired knowledge, important changes of personality (apathy, inertia or depression), slowed thought processes (or bradyphrenia). It is also marked by overwhelming signs of frontal dysfunction. Cognitive and behavioural disturbances are frequently combined to movement disorders (tremor, chorea, dystonia etc). Anatomical, clinical and scintigraphic data suggest that the frontal signs result from a disconnection of the frontal cortex from the basal ganglia. Therefore it is probably more accurate to use the term subcortico-frontal dementia. This pattern of dementia, clearly different from a cortical dementia as dementia of Alzheimer's disease, may be described in a wide range of diseases which mainly involve the subcortical areas: some cases of Parkinson's disease, Progressive Supranuclear Palsy, Huntington's disease, Wilson's disease, the état lacunaire, multiple sclerosis and so on. The concept of subcortical dementia has allowed a better understanding of the role of the basal ganglia and their cortical connections in cognition and behavior. Its neurochemical substrate remains poorly characterized, although the ascending dopaminergic and cholinergic pathways seem to be good candidates, at least in Parkinson's disease.

Impaired source memory in Huntington's disease and its relation to basal ganglia atrophy

Memory for contrived facts and the source of those facts was assessed in a group of early-stage HD patients and an age- and education-equated group of healthy control subjects. Fact recall did not differ significantly between the groups, but erroneous source attributions were more common among the HD patients. Like individuals with frontal lobe damage, HD patients have impaired memory for the source of learned information. Volume of the left caudate nucleus on MRI scans correlated with fact recall and source memory measures. These results suggest that this nucleus, or its neocortical projections, play an important role in the coding of context.

Rationale for intrastriatal grafting of striatal neuroblasts in patients with Huntington's disease

Huntington's disease is a genetic disease, autosomal and dominant, that induces motor disorders, an inexorable deterioration of higher brain functions and psychiatric disturbances. At present, there are no known therapeutics against Huntington's disease. The Network of European CNS Transplantation and Restoration (NECTAR) has begun a program aimed at defining the conditions under which intrastriatal transplantation of fetal striatal cells could be attempted as an experimental treatment for Huntington's disease. This review presents the reasons why our group is considering participating in these trials. The validity of this therapeutic approach is supported by three main series of data: (i) neuropathological, clinical and imaging data indicate that Huntington's disease is, above all, a localized affection of a specific neuronal population ("medium-spiny" neurons) in the striatum; (ii) a large body of experimental results, obtained in rats and non-human primates, demonstrates that transplanted fetal striatal cells are able to integrate the host brain and to substitute for previously lesioned host striatal neurons; (iii) expertise in clinical neural transplantation has now been acquired from the treatment of patients with Parkinson's disease. These different sets of data are presented and discussed in this review. There are a number of problems which do not yet appear to be entirely resolved, nor are they likely to be using the experimental models currently available. These problems are identified and explicitly presented as working hypotheses. (1) Anatomo-functional results obtained in rodents and non-human primates with excitotoxic striatal lesions can serve as a basis for the extrapolation of what can be obtained from patients with Huntington's disease. (2). Huntington's disease can be efficiently fought by substituting degenerated striatal neurons alone. (3) Huntington's disease is due to a genetic defect which either hits the neurons that carry it directly or hits them indirectly only after several decades. Transplanted neurons, because they do not carry the gene or because they are of fetal origin, will not be rapidly affected by the ongoing disease process. Given the current state of knowledge, intracerebral transplantation appears to be the most serious opportunity (if not the only one that has been experimentally validated) for clinical improvement to be obtained in patients with Huntington's disease. The purpose of this review is to open a scientific discussion on its experimental bases before actual clinical trials start.

Cognitive function in early adult and adult onset myotonic dystrophy

INTRODUCTION

Most studies revealing intellectual deficits in myotonic dystrophy (MyD) involved heterogeneous groups of patients with respect to intelligence and onset of disease. The present study was undertaken to investigate whether patients with early adult and adult MyD show subtle cognitive deficits despite a normal intelligence.

MATERIALS AND METHODS

We compared 26 MyD patients of normal intelligence with mild symptoms and early adult and adult onset to 25 matched control subjects (CS) on a range of neuropsychological tests and a number of motor tasks of increasing complexity, which required increasing cognitive control.

RESULTS

The groups did not differ as far as the neuropsychological tests were concerned, with the exception of the Stroop Color Word Test. With respect to motor performance, the MyD patients were poorer scorers on simple and automatic motor tasks than CS, but the difference disappeared as the complexity of the tasks increased and required correspondingly more cognitive control.

CONCLUSION

We found hardly any evidence of cognitive dysfunction in our group of MyD patients with early adult and adult onset.

Neocortical neurotransmitter markers in Huntington's disease

Several neurotransmitter markers were determined in post mortem tissue from temporal and frontal cortex in Huntington's disease in order to identify and understand the specific neuronal losses that occur in the neocortex in this disease. Decreases in GABA and glutamate concentrations were identified, together with increases in metabolites of dopamine and 5-hydroxytryptamine, indicative of regulatory changes presumably induced by the neuronal deficits. There is also evidence for abnormal cortical tryptophan metabolism. These changes may well contribute to some of the behavioural symptoms of the disease.

Cortical and striatal neurone number in Huntington's disease

The total cortical and striatal neurone and glial numbers were estimated in five cases of Huntington's disease (three males, two females) and five age- and sex-matched control cases. Serial 500-microns-thick gallocyanin-stained frontal sections through the left hemisphere were analysed using Cavalieri's principle for volume and the optical disector for cell density estimations. The average cortical neurone number of five controls (mean age 53 +/- 13 years, range 36-72 years) was 5.97 x 10(9) +/- 320 x 10(6), the average number of small striatal neurones was 82 x 10(6) +/- 15.8 x 10(6). The left striatum (caudatum, putamen, and accumbens) contained a mean of 273 x 10(6) +/- 53 x 10(6) glial cells (oligodendrocytes, astrocytes and unclassifiable glial profiles). The mean cortical neurone number in Huntington's disease patients (mean age 49 +/- 14 years, range 36-75 years) was diminished by about 33% to 3.99 x 10(9) +/- 218 x 10(6) nerve cells (P < or = 0.012, Mann-Whitney U-test). The mean number of small striatal neurones decreased tremendously to 9.72 x 10(6) +/- 3.64 x 10(6) (-88%). The decrease in total glial cells was less pronounced (193 x 10(6) +/- 26 x 10(6)) but the mean glial index, the numerical ratio of glial cells per neurone, increased from 3.35 to 22.59 in Huntington's disease. Qualitatively, neuronal loss was most pronounced in supragranular layers of primary sensory areas (Brodmann's areae 3,1,2; area 17, area 41). Layer IIIc pyramidal cells were preferentially lost in association areas of the temporal, frontal, and parietal lobes, whereas spared layer IV granule cells formed a conspicuous band between layer III and V in these fields. Methodological issues are discussed in context with previous investigations and similarities and differences of laminar and lobar nerve cell loss in Huntington's disease are compared with nerve cell degeneration in other neuropsychiatric diseases.

Huntington's disease: update and review of neuropsychiatric aspects

OBJECTIVE

This article presents a general update on Huntington's disease (HD) and reviews the psychiatric and cognitive features of this disorder.

METHOD

HD is discussed in five sections: an introduction and update, the psychiatric aspects, the cognitive aspects, brain-behavior relationships, and the differential diagnosis and management.

RESULTS

Recent advancements in HD include the identification of presymptomatic testing methods and HD gene defect, structural and metabolic neuroimaging findings, and a neuropsychological profile. HD is associated with mood disorders, personality changes, irritable and explosive behavior, a schizophrenia-like illness, suicidal behavior, sexuality changes, and specific cognitive deficits.

CONCLUSIONS

HD results in organic mental disorders from dysfunction of prefrontal-subcortical circuits coursing through the caudate nuclei. The diagnosis of HD is aided by genetic testing, neuroimaging, and neuropsychological testing. Management involves education, genetic counseling and psychotropic medications. Finally, the future of HD holds promise for the development of rational, neurobiologically-based treatments and genetically engineered therapies.

Assessment of adaptive functioning in Huntington's disease

The Huntington's Disease Activities of Daily Living (HD-ADL) scale is a 17-item informant-completed instrument for rating adaptive functioning in Huntington's disease (HD) patients. To assess the reliability and clinical correlates of the HD-ADL, it was administered along with the Mini-Mental State Exam (MMSE) and Quantified Neurological Exam (QNE) to 93 HD patients. The HD-ADL has high internal consistency (coefficient alpha = 0.91). Principal components factor analysis of the HD-ADL revealed four factors (General Functioning, Domestic Activities, Home Upkeep, and Family Relationships) accounting for 72% of the total variance. MMSE score, motor impairment score, and duration of disease were the best predictors of HD-ADL score. Similar results were obtained in an independent replication sample of patients. The HD-ADL scores correlate with Shoulson and Fahn's total functional capacity (TFC) index (r = -0.89). The HD-ADL scale is a reliable and valid instrument for assessing adaptive function in HD patients.

Movement disorders and psychological tests of frontal lobe function in schizophrenic patients

Neuropsychological tests of frontal lobe functions were undertaken in 46 chronic schizophrenic patients who were also rated for movement disorders. Tardive dyskinesia was found to have significant associations with most of these psychological tests. The possible mechanisms are discussed within the context of known neostriatal psychological functions.

Putamen volume reduction on magnetic resonance imaging exceeds caudate changes in mild Huntington's disease

The characteristic pathological features of Huntington's disease (HD) are neostriatal atrophy and neuronal loss. Although neuroradiological studies often show caudate atrophy in patients with moderate HD, frequently no caudate atrophy is found early in the illness. There have been no quantitative reports to date on in vivo putamen volume measures in mild HD, although the structure is known to be neuropathologically involved in the illness. We measured volumes of caudate nucleus and putamen and bicaudate ratios (BCR) from magnetic resonance images, blind to diagnosis, in 15 patients with mild HD and 19 age- and sex-matched control subjects using a computerized image analysis system. The region showing greatest atrophy was the putamen, which was reduced 50.1% in mean volume in HD patients compared with control subjects (p less than 0.000001). In contrast, caudate volume was reduced 27.7% (p = 0.004). BCR was increased 28.5% in HD patients (p = 0.0002). Discriminant function analysis was 94% effective in identifying the diagnostic group based on putamen volume alone, whereas caudate measures had considerable overlap. Correction of putamen volume for head size led to 100% separation by group. Putamen measures and BCR correlated with neurological examination scores but caudate volume did not. Volumetric measurement of putamen is a more sensitive indicator of brain abnormalities in mild HD than measures of caudate atrophy.