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Biomedical subjects

B Sahakian

Publications and source records attributed to B Sahakian.

12 recordsLinked to original sources
PubMed2004

The specificity of clinical characteristics in adults with attention-deficit/hyperactivity disorder: a comparison with patients with borderline personality disorder.

Characteristics of DSM-IV attention-deficit/hyperactivity disorder (ADHD) in adults can also be found as part of other psychiatric disorders. This study investigated the specificity of adult ADHD features in relation to patients with borderline personality disorder (BPD), a syndrome which shares some of its intrinsic features with ADHD and often co-occurs with ADHD. A group of 20 adult patients selected on the basis of a diagnosis of ADHD and 20 patients selected on the basis of a diagnosis of BPD were assessed by the self-report Attention Deficit Scales for Adults (ADSA). The two groups were matched for age, verbal IQ and gender. Of the nine ADSA scales, seven showed significant inter-group differences, in particular involving attention, organisation and persistence. The 'Consistency/Long-Term' scale, which mainly reflects impaired task and goal persistence, was the best discriminator between the groups. Furthermore, ratings on this scale correlated significantly with the error score of a computer-administered task of spatial working memory, the performance of which has been reported to be impaired in patients with ADHD. The results provide further validation for the ADSA scales and support a previous claim that 'long-term consistencies', i.e., related to task and goal persistence, is 'the centrepiece behavioural issue' for adults with ADHD.

Adult↗
PubMed1999

Huntington's disease progression. PET and clinical observations.

Using serial [(11)C]SCH 23390- and [11C]raclopride-PET, we have measured the rate of loss of striatal dopamine D1 and D2 receptor binding over a mean of 40 months in nine asymptomatic adult Huntington's disease mutation carriers, four patients with symptomatic disease, seven mutation-negative controls and three subjects at risk for the disease. Eight of the nine asymptomatic Huntington's disease mutation carriers had serial [11C]raclopride-PET and showed a mean annual loss of striatal D2 binding of 4.0%. Only five of these eight, however, showed active progression, and they had a mean annual loss of D2 binding of 6.5%. All nine asymptomatic mutation carriers had serial [11C]SCH 23390-PET and showed a mean annual loss of striatal D1 binding of 2. 0%. Four of these subjects demonstrated active progression and they had a mean annual loss of 4.5%. Our four symptomatic Huntington's disease patients showed a mean annual loss of D2 binding of 3.0% and of D1 binding of 5.0%. Loss of striatal D1 and D2 binding was significantly greater in the known mutation carriers than in the combined at-risk and gene-negative groups (P < 0.05). At follow-up PET all subjects were clinically assessed using the Unified Huntington's Disease Rating Scale. Scores for motor function and total functional capacity correlated with PET measures of striatal dopamine receptor binding both in the asymptomatic mutation carriers (D1, P < 0.01) and across the combined asymptomatic and clinically affected Huntington's disease mutation carrier group (D1 and D2, P < 0.001). We conclude that PET measures of striatal D1 and D2 dopamine binding can be used to identify asymptomatic Huntington's disease mutation carriers who are actively progressing and who would thus be suitable for putative neuroprotective therapies. Measures of disease progression rates in Huntington's disease patients and asymptomatic mutation carriers will be of critical importance in future trials of experimental restorative treatments.

Adult↗
PubMed1997

Can frontotemporal dementia and Alzheimer's disease be differentiated using a brief battery of tests?

OBJECTIVE: To compare the performance of patients with frontotemporal dementia (FTD) and Alzheimer's disease (AD) on a range of simple neuropsychological tests. DESIGN: A battery of neuropsychological tests easily applied at the bedside, consisting of traditional tests of memory, attention and executive function, were given together with tests of motor sequencing and examination of frontal release signs. In addition, we devised a theoretically motivated test of dual attention-a story with distraction which also contained a 'social dilemma'. SETTING: Specialist memory and cognitive disorders clinic. PATIENTS: 12 patients with FTD and 12 patients with AD, matched for overall level of dementia on the Mini-Mental State Examination, were selected. RESULTS: In general, the difference in results between FTD and AD patients was small. However, a composite score derived from the presence of a grasp and pout reflex, the number of perseverations during category fluency for animals and response to the social dilemma within the two stories produced a sensitivity of 83.3% and specificity of 91.6%. There was also a highly significant difference between patients with FTD and AD in scores achieved on the Clinical Dementia Rating Scale reflecting the marked change in behaviour that patients with FTD suffer, even at a stage when memory functions are well preserved. CONCLUSION: Traditional neuropsychological tests were poor at differentiating cases of FTD and AD; however, a composite (SIFTD) score appears potentially useful but requires prospective validation. Better methods of assessing the changes in comportment that characterize the early stages of FTD are required.

Aged↗
PubMed1993

Thalamic radiodensity and cognitive performance in mild and moderate dementia of the Alzheimer type.

Eighteen patients with mild to moderate dementia of the Alzheimer type underwent cranial computed tomography (CT) and tests of visual attention, recognition and learning. Two subgroups emerged. Subgroup 1 was made up of ten patients who showed impaired visual recognition learning and memory, but intact attention in marked contrast to subgroup 2, which was made up of eight patients, in whom all of these functions were impaired. Planimetric and densitometric CT measurements yielded one significant difference between the two subgroups: a decreased radiodensity in the dorsomedial thalamus of the patients from subgroup 2. Lower radiodensity in the right dorsomedial thalamic area was significantly correlated with impaired performance on the test of attentional set shifting, more specifically, with deficits at the reversal learning stage. These results are interpreted in the context of recent evidence linking reversal learning to a neural network comprising the cholinergic basal forebrain, the amygdala and the orbitofrontal cortex, as well as the mediodorsal nucleus, and recent evidence of cholinergic deficits in this structure in patients with Alzheimer's disease.

Aged↗
PubMed1992

Tacrine in Alzheimer's disease. Time course of changes in cognitive function and practice effects.

This paper concerns certain questions which arose during the analysis of a trial showing positive effects of tacrine in Alzheimer's disease. Cognitive improvement occurred during the first two weeks, reached a maximum at one month and was maintained during the rest of the three-month treatment period. Rebound effects were not detected in any of the key outcome variables, but were suggested by one of the supporting cognitive tests and other measures. Practice effects occurred on tests which were repeated at short intervals or too frequently. The paper discusses the significance of these findings for the interpretation of other trials and for practical management.

Aged↗
PubMed1989

The effects of nicotine on attention, information processing, and short-term memory in patients with dementia of the Alzheimer type.

Nicotine in patients with dementia of the Alzheimer type (DAT) produced a significant and marked improvement in discriminative sensitivity and reaction times on a computerised test of attention and information processing. Nicotine also improved the ability of DAT patients to detect a flickering light in a critical flicker fusion test. These results suggest that nicotine may be acting on cortical mechanisms involved in visual perception and attention, and support the hypothesis that acetylcholine transmission modulates vigilance and discrimination. Nicotine may therefore be of some value in treating deficits in attention and information processing in DAT patients.

Adult↗