Locus of control and the spontaneous use of mnemonic strategies in a motor memory task

A test was developed which enabled isolating the effects of locus of control over specific parts of the learning process, while studying its effect on the spontaneous use of mnemonic strategies. Fifty-six adults with mild or moderate mental retardation were randomly assigned to four groups that differed by both internal versus external control, and empty versus filled interval. Recall after an empty interval was significantly better than that following a filled one, suggesting the spontaneous use of mnemonic strategies. No effect was found for the locus of control variable. A longer "warm up decrement" in this population is suggested.

Motor and cognitive aspects of motor retardation in depression

BACKGROUND

Motor retardation is a common feature of major depressive disorder having potential prognostic and etiopathological significance. According to DSM-IV, depressed patients who meet criteria for psychomotor retardation, must exhibit motor slowing of sufficient severity to be observed by others. However, overt presentations of motor slowing cannot distinguish slowness due to cognitive factors from slowness due to neuromotor disturbances.

METHODS

We examined cognitive and neuromotor aspects of motor slowing in 36 depressed patients to test the hypothesis that a significant proportion of patients exhibit motor programming disturbances in addition to psychomotor impairment. A novel instrumental technique was used to assess motor programming in terms of the subject's ability to program movement velocity as a function of movement distance. A traditional psychomotor battery was combined with an instrumental measure of reaction time to assess the cognitive aspects of motor retardation.

RESULTS

The depressed patients exhibited significant impairment on the velocity scaling measure and longer reaction times compared with nondepressed controls. Approximately 40% of the patients demonstrated abnormal psychomotor function as measured by the traditional battery; whereas over 60% exhibited some form of motor slowing as measured by the instruments. Approximately 40% of the patients exhibited parkinsonian-like motor programming deficits. A five-factor model consisting of motor measures predicted diagnosis among bipolar and unipolar depressed patients with 100% accuracy.

LIMITATIONS

The ability of motor measures to discriminate bipolar from unipolar patients must be viewed with caution considering the relatively small sample size of bipolar patients.

CONCLUSIONS

These findings suggest that a subgroup of depressed patients exhibit motor retardation that is behaviorally similar to parkinsonian bradykinesia and may stem from a similar disruption within the basal ganglia.

Intra-operative direct electrical stimulations of the central nervous system: the Salpêtrière experience with 60 patients

Indications of surgical treatment for lesions in the central nervous system depend on the risk of a definitive neurological deficit, related to the benefit of resection. Detection of eloquent areas is then necessary because of major individual variability. Neuro-imaging functional techniques are in development and are beginning to be efficient for cortical sensorymotor mapping, but still lack sensitivity and specificity for language mapping, and remain unable to give real-time data during surgery and to perform sub-cortical mapping. The more precise and reliable method of functional mapping is represented by the intra-operative direct electrical stimulations (DES), which allow identification and preservation of essential pathways for motricity, sensibility and language, at each level of the central nervous system (cortico-subcortical). We report our experience of DES in the surgery of tumours and vascular malformations located in supra-tentorial brain eloquent areas, with a consecutive series of 60 patients operated on under general or local anaesthesia, from November 1996 until May 1999 in our department at La Salpêtrière Hospital. Presenting symptoms in the 60 subjects (39 males, 21 females, mean age: 45 years) were seizures in 37 cases with normal clinical examination, and mild neurological deficit in 29 cases. MRI showed 60 supra-tentorial brain lesions: 30 precentral, 12 postcentral, 14 perisylvian in the dominant hemisphere, 4 deep-seated. All subjects underwent surgical resection using DES, with supratentorial cortico-subcortical mapping under general anaesthesia for motor areas detection in 43 cases and under local anaesthesia for sensori-motor and/or language tasks in 17 cases. The final histological diagnosis was 44 gliomas (31 low-grade and 13 high-grade), 9 metastasis, 3 cavernomas, 4 arteriovenous malformations (AVM). Resection was total or subtotal in 52 cases (87%) and partial in 8 cases (13%). 29 patients had no post-operative deficit, while the other 31 patients were impaired post-operatively, with in all cases, except 3, a complete recovery delayed for 15 days to 3 months (overall morbidity: 5%). The median follow up was 14 months. Intra-operative direct electrical stimulations of the central nervous system constitute a reliable, precise and safe method, allowing the realization of a functional mapping useful for all operations of lesions located in eloquent areas. This technique allows a minimization of definitive post-operative neurological deficit, and concurrently an improvement in the quality of resection.

Psychogenic non-epileptic seizures: can we make a positive diagnosis?

Many disorders other than epilepsy are characterized by paroxysmal events. Psychogenic non-epileptic seizures (NES) form one differential diagnostic group which mimic epileptic phenomena and are caused by various psychic disorders. The diagnosis of NES is mostly based on the exclusion of epilepsy. We review the histories of six patients, who were hospitalized in an epilepsy unit and were diagnosed as having psychogenic NES. Most of them had been previously given the diagnosis of epilepsy. It is suggested that for accurate diagnosis it is very important that a patient initially undergoes psychiatric assessment along with standard diagnostic procedures (e.g. neurologic, psychological and physical investigations), that may encourage making a positive diagnosis of non-epilepsy.

Neuropsychological, learning and psychosocial profile of primary school aged children with the velo-cardio-facial syndrome (22q11 deletion): evidence for a nonverbal learning disability?

In this exploratory study, the neuropsychological and learning profile of nine primary school age children with velo-cardio-facial syndrome (VCFS) was studied by systematic neuropsychological testing. In five out of nine children, the following profile was found: a VIQ-PIQ discrepancy (in favor of the VIQ), significantly better scores (.05 level) for reading (decoding) and spelling compared to arithmetic, deficient tactile-perceptual skills (difficulties mainly on the left side of the body), weak but not deficient visual-perceptual abilities, deficient visual-spatial skills, extremely poor psychomotor skills (gross motor skills more deficient than fine motor skills), problems with processing of new and complex material, poor visual attention, good auditory memory and relatively good language skills. These findings correspond to the pattern of neuropsychological assets and deficits that has been described for the syndrome of nonverbal learning disabilities (NLD) (Rourke, 1987, 1988, 1989, 1995). The psychosocial profile of all nine children with VCFS also correspond to that of children with NLD. Further studies on the relationship between cognitive function, behavior, psychiatric disorder and abnormalities in brain anatomy in young people with VCFS will be needed. In clinical practice, it is worthwhile exploring in greater depth the neuropsychological functions of children with VCFS to rule out NLD, since they may benefit from specific remediation following the learning principles of the NLD-treatment.

Age-related behavioural deficits in transgenic mice expressing the HIV-1 coat protein gp120

Transgenic mice expressing HIV-1 coat glycoprotein gp120 in brain glial cells were previously shown to display AIDS dementia-like neuropathological changes and reduced hippocampal long-term potentiation. In this report, neuromotor and cognitive performance in 3- and 12-month-old gp120-expressing mice was compared with wildtype controls. Rotarod and cage activity measures showed no significant differences between transgenic animals and controls of either age. Open field activity was slightly altered in 12-month-old gp120 animals (reduced corner crossings and dwell in centre), but not in the 3-month-olds. Cognitive assessment using the Morris water maze showed unimpaired performance in 3-month-old mice during acquisition and (no-platform) probe trials. In 12-month-old gp120 animals, escape latency and swimming velocity during the acquisition trials were significantly reduced, but performance improved at roughly the same rate as in control animals. However, the probe trials revealed a highly significant reduction in spatial retention in transgenic mice of this age. This demonstration of age-dependent impairments in open field activity and spatial reference memory may relate to cognitive and neuromotor deficits seen in a proportion of HIV-1-infected individuals.

Quantifying the performance impairment associated with fatigue

The present study systematically compared the effects of fatigue and alcohol intoxication on a range of neurobehavioural tasks. By doing so, it was possible to quantify the performance impairment associated with fatigue and express it as a blood alcohol impairment equivalent. Twenty-two healthy subjects aged 19-26 years participated in three counterbalanced conditions. In the sustained wakefulness condition, subjects were kept awake for 28 h. In the alcohol and placebo conditions, subjects consumed either an alcoholic or non-alcoholic beverage at 30 min intervals, until their blood alcohol concentration reached 0.10%. In each session, performance was measured at hourly intervals using four tasks from a standardised computer-based test battery. Analysis indicated that the placebo beverage did not significantly effect mean relative performance. In contrast, as blood alcohol concentration increased performance on all the tasks, except for one, significantly decreased. Similarly, as hours of wakefulness increased performance levels for four of the six parameters significantly decreased. More importantly, equating the performance impairment in the two conditions indicated that, depending on the task measured, approximately 20-25 h of wakefulness produced performance decrements equivalent to those observed at a blood alcohol concentration (BAC) of 0.10%. Overall, these results suggest that moderate levels of fatigue produce performance equivalent to or greater than those observed at levels of alcohol intoxication deemed unacceptable when driving, working and/or operating dangerous equipment.

A meta-analysis of clonidine for symptoms of attention-deficit hyperactivity disorder

OBJECTIVE

Meta-analysis was used to review the literature on the clinical use of clonidine to treat symptoms of attention-deficit hyperactivity disorder (ADHD).

METHOD

A review of the literature from 1980 to 1999 revealed 39 studies that reported clonidine's efficacy and side effects for symptoms of ADHD and comorbid conditions. Of these, 11 reports provided sufficient information to be included in a meta-analysis.

RESULTS

Meta-analysis using weighted variables revealed clonidine demonstrates a moderate effect size of 0.58 +/- 0.16 (95% confidence interval = 0.27-0.89) on symptoms of ADHD in children and adolescents with ADHD and ADHD comorbid with conduct disorder, developmental delay, and tic disorders.

CONCLUSIONS

Clonidine may be an effective second-tier treatment for symptoms of ADHD, but it has an effect size less than that of stimulants. Clinical use of clonidine is associated with many side effects.

Distinctive neurobehavioral features among neurodegenerative dementias

The distinctive neuropsychiatric features of Alzheimer's disease (AD), dementia with Lewy bodies (DLB), and frontotemporal dementia (FTD) were investigated by using the Neuropsychiatric Inventory. The patients with FTD had significantly more euphoria, aberrant motor activity, and disinhibition and significantly fewer delusions compared with the patients with AD or DLB. The patients with DLB had significantly more hallucinations compared with the AD or FTD patients. The findings clearly demonstrate that AD, DLB, and FTD have distinctive neuropsychiatric features, which may correspond to different patterns of cerebral involvement characteristic of these three major degenerative dementias.

Alteration of intention and self-initiated action associated with bilateral anterior cingulotomy

Neuropsychological manifestations of bilateral anterior cingulate cortex lesions were studied in patients treated with cingulotomy for chronic intractable pain. Cingulotomy patients more than 1 year postsurgery were contrasted with nonsurgical chronic pain patients. Patients were assessed on a neuropsychological battery, including measures of response intention, initiation, generation, and persistence. Cingulotomy patients were intact across most cognitive domains, but they showed deficits of focused and sustained attention as well as mild executive dysfunction. Self-initiated responding--including spontaneous verbal utterances and unstructured design fluency--was most impaired. Results indicate that the greatest impact of cingulotomy lesions is on response intention and self-initiated behavior, with reduced behavioral spontaneity.

Three dimensions of depression in patients with acute psychotic disorders: a replication study

Depressive symptoms in psychotic disorders are of high relevance but seem to be heterogeneous when assessed with a standard rating scale. The present analysis is a replication study on the dimensionality of the Bech-Rafaelsen Melancholia Scale (BRMES) in acutely psychotic patients with substantial depression defined according to a functional approach across the nosological borders of schizophrenia with major affective symptoms, schizoaffective disorder, depressed subtype, and major depression with psychotic features. The baseline data of 123 patients participating in a multicenter pharmacological trial were evaluated with structural equation models. A previously reported three-dimensional model of the BRMES comprising the facets retardation, depressive core symptoms, and accessory depressive symptoms was cross-validated by confirmatory factor analysis (CFA). The three-dimensional model proved to be superior to one-, two-, or four-factor models with respect to goodness-of-fit (goodness-of-fit index [GFI] = 0.91 and comparative fit index [CFI] = 0.89) and parsimony (adjusted GFI [AGFI] = 0.85). When comparing the present model with the previously reported model, a highly satisfactory correspondence emerged (CFI = 0.87). The results corroborate our previous findings that depression-like symptoms in acutely psychotic patients assessed by the BRMES can best be represented by a three-dimensional model and should not be treated as a homogeneous syndrome.

Gait in stroke: assessment and rehabilitation

This article discusses the assessment and treatment of gait disorders after stroke. After consideration of the effects (of the disturbed motor control resulting from stroke) on the gait movements and the expected rate of recovery of walking capacity, different methods of assessment are considered. Emphasis is placed on selecting the appropriate measurement tool according to the individual's level of function. Also, the need to measure walking performance under different environmental constraints and the importance of instrument responsiveness to change over the range of walking disabilities are discussed. Task-related training with the opportunity for large amounts of practice is recommended to improve walking performance after stroke.

Early prediction of neurologic outcome after perinatal depression

Evaluation is presented of whether or not a detailed neuromotor examination at 3 months of age could predict later neurologic abnormalities among term infants with perinatal depression. In a prospective cohort, infants were neurologically evaluated at 3 and 12 months. Infants were scored from 0 to 5 according to a new neuromotor scoring system. The neuromotor score at 3 months (NMS-3) was compared with the NMS at 12 months (NMS-12). Seventy-four infants were enrolled in the study; nine were lost to follow-up, and five died before reaching 1 year. Sixty infants were examined (neurologic abnormalities = 52%, normal = 48% at 1 year). The NMS-3 correlated strongly with the NMS-12 and the results of the 12-month neurologic examination. All infants with a NMS-3 of 5 had neurologic abnormalities at 1 year. Infants with neonatal seizures had a significantly increased risk of developmental abnormalities at 1 year. Eighteen infants exhibited transient abnormalities. Using a simple scoring system, the results of the early neurologic examinations correlated strongly with outcome among term infants with perinatal depression. A subgroup of infants had transient abnormalities. These findings suggest that in term high-risk infants, the 1-year neurologic outcome can be predicted at 3 months of age using these parameters.

Carbohydrate-deficient glycoprotein syndrome type II

The carbohydrate-deficient glycoprotein syndromes (CDGS) are a group of autosomal recessive multisystemic diseases characterized by defective glycosylation of N-glycans. This review describes recent findings on two patients with CDGS type II. In contrast to CDGS type I, the type II patients show a more severe psychomotor retardation, no peripheral neuropathy and a normal cerebellum. The CDGS type II serum transferrin isoelectric focusing pattern shows a large amount (95%) of disialotransferrin in which each of the two glycosylation sites is occupied by a truncated monosialo-monoantennary N-glycan. Fine structure analysis of this glycan suggested a defect in the Golgi enzyme UDP-GlcNAc:alpha-6-D-mannoside beta-1,2-N-acetylglucosaminyltransferase II (GnT II; EC 2.4.1.143) which catalyzes an essential step in the biosynthetic pathway leading from hybrid to complex N-glycans. GnT II activity is reduced by over 98% in fibroblast and mononuclear cell extracts from the CDGS type II patients. Direct sequencing of the GnT II coding region from the two patients identified two point mutations in the catalytic domain of GnT II, S290F (TCC to TTC) and H262R (CAC to CGC). Either of these mutations inactivates the enzyme and probably also causes reduced expression. The CDG syndromes and other congenital defects in glycan synthesis as well as studies of null mutations in the mouse provide strong evidence that the glycan moieties of glycoproteins play essential roles in the normal development and physiology of mammals and probably of all multicellular organisms.

Children with autism experience problems with both objects and people

Kanner (1943), in his classic account, described autism as a specific impairment in interpersonal relations which leaves the child's uses of objects relatively unaffected. This combination of the difficulties in relating to people and the supposedly "excellent" relations to objects figures centrally within many of the current theories of autism, which have had relatively little to say on the question of object use. This paper draws attention to evidence of widespread impairments in relating to objects, not only in interpersonal aspects of object use but also in early sensorimotor exploration and the functional and conventional uses of objects. In stressing these problems with objects, our purpose is not to downplay the social dimension of autism, but rather to highlight the reciprocal nature of the interactions between the child, other people, and objects. Given the evidence that other people play an important role in introducing objects to children, we propose that an impairment in interpersonal relations should itself lead us to expect corresponding disruption in the autistic child's use of objects. Conversely, an unusual use of objects is likely to manifest itself in disturbances in relating to other people, given the importance of a shared understanding and use of objects in facilitating interaction.

Acquired microcephaly after low Apgar score in Zimbabwe

Serial head circumference measurements were made on 165 African babies born with a 5 min Apgar score of 5 or less. Measurements were taken at birth and at 4, 9, and 12 months of age. In the majority of infants the onset of microcephaly could be diagnosed as early as 4 months of age. Twenty-five of the 142 infants were microcephalic at 1 year. Neurological development was impaired in 19 of the 25 (76 per cent) microcephalic infants and in 18 of the 117 (15 per cent) normocephalic infants. Fourteen of the 16 (88 per cent) infants with severe quadriplegia developed microcephaly before the age of 4 months. A decreased rate of head growth during the first 4 months of life in African infants born with a low Apgar score correlates closely with the development of microcephaly. Infants with an acquired microcephaly have a high probability of developing neurologic impairment by the age of 1 year. Serial head circumference measurement in low Apgar score babies in developing countries is an easy, simple, and inexpensive method to detect microcephaly.

[Electrophysiologic diagnosis of 2 psycho-visual syndromes: Balint syndrome and cortical blindness. A propos of a case of Benson progressive posterior atrophy]

Cortical blindness and Balint's syndrome are two pathologies not well-known. It seems therefore interesting to report a typical patient case, suffering from Benson's posterior cortical atrophy, who presented successively both syndromes. The Balint's syndrome, which results from a bilateral parieto-occipital junction brain injury, and combines clinically a specified triad defects: a spatial disorder of attention, a psychic paralysis of gaze and an optic ataxia. The cortical blindness, which is caused by bilateral damage of the occipital lobes (Broadman area 17). Electrophysiologically, the abolition of short-latency components of visual evoked potentials and the presence of long-latency potentials are recorded. Visual strategy and visual evoked potentials are thus the only objective examinations allowing to diagnose and follow up these patient's evolution. In any case, an adequate visual rehabilitation has to be carried out in order to help the patient recovering his autonomy.

Prenatal cocaine and neuromotor outcome at four months: effect of duration of exposure

The effect of prenatal cocaine exposure on the motor development of full-term infants was examined in a prospective study, controlling for maternal characteristics and exposure to other substances. Intrauterine cocaine exposure was determined at birth by maternal self-report and was verified by hair analysis. At 4 months, 120 cocaine-exposed (COC) and 186 non-cocaine-exposed (NON-COC) infants were assessed by blinded examiners using a standard evaluation of neuromotor function, the Movement Assessment of Infants (MAI). Relative to NON-COC infants, COC infants had significantly higher full-scale MAI total risk scores after adjusting for covariates (p = .05). Infants exposed through the third trimester of pregnancy (n = 48) had higher MAI scores for both total risk (p = .02) and Volitional Movement (p = .01), and when compared with infants exposed only within the first two trimesters (n = 72), they had significantly more deficits in Volitional Movement (p = .03). Although MAI scores for the majority of exposed infants were within the normal range, infants exposed through the third trimester were at significantly increased risk for motor dysfunction (relative risk = 1.6; 95% confidence interval = 1.1, 2.8). Intrauterine cocaine exposure had an adverse effect on infant motor development after the neonatal period; this association was related to the timing and duration of gestational exposure. Further study is needed to evaluate the long-term clinical implications of neuromotor abnormalities in prenatally exposed infants.

[Evaluation of cardiovascular and sudomotor functions in Alzheimer's disease]

The assessment of some aspects of cardiovascular and sudomotor system was performed in the group of patients with Alzheimer's disease. No one of patients complained of disturbances arising from these two parts of the vegetative system. The autonomic functions were evaluated by means of: clinical examination, heart rate variability tests at rest, measures of blood pressure and heart rate in supine and standing position and skin sympathetic response. At rest heart rate and its variability as well as blood pressure in the patients did not differ significantly from the results obtained in the healthy controls. On standing, changes in systolic blood pressure and heart rate were recorded in the controls, but not found in the patients. The majority of patients presented with abnormalities in skin sympathetic response: lack of response or prolongation of its latency. The results of motor and sensory nerve conduction studies excluded neuropathic changes in the patients. We conclude that autonomic disturbances accompanied Alzheimer's disease and were probably caused by damaged control mechanisms within the central vegetative system.

Clinical and neuroradiological follow-up in mucopolysaccharidosis type III (Sanfilippo syndrome)

Mucopolysaccharidosis type III (Sanfilippo syndrome) is an autosomal recessive disorder characterised by progressive nervous system involvement with mental retardation, behavioural problems and seizures. Three patients, of 20 months to 12 years of age, were followed up for 3 years both clinically and by using brain magnetic resonance imaging (MRI). Our results suggest that in MPS III patients MRI findings, including atrophy and abnormal or delayed myelination, may precede the onset of overt neurological symptoms. The increasing neurological morbidity is accompanied by different degrees of progressive atrophic changes, mainly affecting the cerebral cortex and the corpus callosum. However, it appears that, across subjects, the rate of MRI changes is unrelated to the severity of the clinical phenotype. On this basis it could be argued that in MPS III the worsening of the neurological symptoms might not necessarily reflect only the progressive cerebral abnormalities detectable by MRI.

An overview of the clinical use of dynamic posturography in the differential diagnosis of balance disorders

Dynamic posturography comprises a series of balance control tests which help physicians overcome numerous diagnostic and treatment challenges arising when examining patients complaining of a debilitating balance disorder. These challenges include the specific differential diagnosis, documentation of symptoms and assessment of functional disability. It must be determined whether the cause of the disability is an organic sensory, deficit, a central nervous system (CNS) lesion or a non-organic (that is, possibly psychogenic or just overtly simulated) disorder. This review is targeted towards providing the reader (a) an overview of the effects sensorimotor deficits have on balance control, specifically vestibulospinal and proprioceptive reflex deficits; and, (b) how these effects may be assessed objectively in a clinical setting to differentiate between various organic and non-organic balance-disorders. The techniques used to study these effects are based on the analysis of both rapid balance-correcting and slow balance-stabilizing responses to fast and slow movements in the pitch plane of the support surface on which the test subject stands.

Motor cortex activation in Parkinson's disease: dissociation of electrocortical and peripheral measures of response generation

This study investigated characteristics of motor cortex activation and response generation in Parkinson's disease with measures of electrocortical activity (lateralized readiness potential [LRP]), electromyographic activity (EMG), and isometric force in a noise-compatibility task. When presented with stimuli consisting of incompatible target and distractor elements asking for responses of opposite hands, patients were less able than control subjects to suppress activation of the motor cortex controlling the wrong response hand. This was manifested in the pattern of reaction times and in an incorrect lateralization of the LRP. Onset latency and rise time of the LRP did not differ between patients and control subjects, but EMG and response force developed more slowly in patients. Moreover, in patients but not in control subjects, the rate of development of EMG and response force decreased as reaction time increased. We hypothesize that this dissociation between electrocortical activity and peripheral measures in Parkinson's disease is the result of changes in motor cortex function that alter the relation between signal-related and movement-related neural activity in the motor cortex. In the LRP, this altered balance may obscure an abnormal development of movement-related neural activity.

Retardation in depression: assessment by means of simple motor tasks

BACKGROUND

Psychomotor retardation in depression has mostly been assessed with tasks requiring both cognitive and motor processes. This study tested whether retardation could be measured if the cognitive demands of the task were minimal.

METHODS

30 inpatients with a major depressive episode were compared one week after the start of antidepressant treatment, to 30 healthy control persons, matched for age, sex and educational level. Tests consisted of ten simple drawing tasks. The kinematics of drawing movements were recorded using a specially designed pen, a graphics tablet and a personal computer.

RESULTS

Patients showed marked motor slowing on all the tasks: longer movement durations, longer pauses and lower velocities.

CONCLUSIONS

Psychomotor retardation in depressed patients treated with antidepressants occurs during drawing tasks, in which the cognitive demands are minimal and less than those required in the figure copying tasks used in our previous studies.

LIMITATIONS

The use of co-medication can have influenced the results, although no correlations were found between the use of medication and the kinematic variables.

CLINICAL RELEVANCE

Detailed registration and analysis of drawing movements enable a more precise diagnosis of psychomotor disturbances in depressed patients.

Brain structural and cognitive correlates of clock drawing performance in Alzheimer's disease

The Clock Drawing Test (CDT) is widely used in the assessment of dementia and is known to be sensitive to the detection of deficits in neurodegenerative disorders such as Alzheimer's disease (AD). CDT performance is dependent not only on visuospatial and constructional abilities, but also on conceptual and executive functioning; therefore, it is likely to be mediated by multiple brain regions. The purpose of the present study was to identify component cognitive processes and regional cortical volumes that contribute to CDT performance in AD. In 29 patients with probable AD, CDT performance was significantly related to right-, but not left-hemisphere, regional gray matter volume. Specifically, CDT score correlated significantly with the right anterior and posterior superior temporal lobe volumes. CDT scores showed significant relationships with tests of semantic knowledge, executive function, and visuoconstruction, and receptive language. These results suggest that in AD patients, CDT performance is attributable to impairment in multiple cognitive domains but is related specifically to regional volume loss of right temporal cortex.