The main objectives of this study were to examine the relationship between cognitive deficits, as measured by the Mini-Mental Status Examination (MMSE), and decision-making capacity and to determine whether the sensitivity and specificity of the MMSE varied based upon the patient population assessed. Using a sample size of 152 patients and varying cutoff scores, the MMSE demonstrated extremely poor sensitivity. In contrast, the MMSE had excellent specificity when scores of 19 or less were obtained. In our sample, not one patient, regardless of diagnosis, was deemed to have capacity if their MMSE score was below 20. However, reliance on the MMSE for scores above 19 would too frequently lead to misclassification and incorrect assumptions about a patient's decision-making abilities. Although a score below 20 consistently yielded findings of incapability in our sample, it remains our opinion that the MMSE should not be used as a stand-alone tool to make determinations related to capacity, especially when considering the complexities associated with capacity evaluations and the vital areas, such as executive functioning and individual values and beliefs, which are omitted by the MMSE.
Three-dimensional kinematic analysis of line of gaze, arm and ball was used to describe the visual and motor behaviour of male adolescents diagnosed with attention deficit hyperactivity disorder (ADHD). The ADHD participants were tested when both on (ADHD-On) and off (ADHD-Off) their medication and compared to age-matched normal controls in a modified table tennis task that required tracking the ball and hitting to cued right and left targets. Long-duration information was provided by a pre-cue, in which the target was illuminated approximately 2 s before the serve, and short-duration information by an early-cue illuminated about 350 ms after the serve, leaving approximately 500 ms to select the target and perform the action. The ADHD groups differed significantly from the control group in both the pre-cue and early-cue conditions in being less accurate, in having a later onset and duration of pursuit tracking, and a higher frequency of gaze on and off the ball. The use of medication significantly reduced the gaze frequency of the ADHD participants, but surprisingly this did not lead to an increase in pursuit tracking, suggesting a barrier was reached beyond which ball flight information could not be processed. The control and ADHD groups did not differ in arm movement onset, duration and velocity in the short-duration early-cue condition; in the long-duration pre-cue condition, however, the ADHD group's movement time onset and arm velocity differed significantly from controls. The results show that the ADHD groups were able to process short-duration information without experiencing adverse effects on their motor behaviour; however, long-duration information contributed to irregular movement control.
This preliminary study investigated the potential of a cerebral lateralization technique that measures both, temporal judgements to sensory stimuli and interhemispheric transfer time (IHTT), as an outcome measure in multiple sclerosis (MS). Tactile stimulation was delivered to one or both hands by mechanical tactile stimulators. Pairs of light emitting diodes were presented to hemifields for visual stimulation. Response consisted of a binary forced-choice (YES/NO) judgement as to the simultaneity of the onset of pairs of stimuli. Both tactile and visual temporal thresholds were significantly higher in MS patients than controls in every presentation condition. IHTT estimates (threshold differences between unilateral and bilateral presentations) for the tactile and visual tasks were also significantly longer in patients than controls. Age correlated with sensory temporal thresholds for the control group only. These findings suggest that this technique may be a useful outcome measure in MS. We hypothesize that myelin injury slows central conduction therefore impairing the ability to judge the onset of sensory stimuli and increasing IHTTs.
This study investigated temporal processing abilities, hemispheric asymmetry, interhemispheric transfer, and stimulant medication effects in adolescents with attention deficit hyperactivity disorder (ADHD). Pairs of light emitting diodes in a visual half-field display (i.e., bilateral and unilateral presentations) were presented to examine medication effects, temporal judgments, hemispheric asymmetry, and interhemispheric transfer in male adolescents with ADHD and matched controls on age and gender. Participants responded (YES/NO) whether pairs of spatially separated diodes were illuminated simultaneously. Stimulant medication did not have an affect on temporal judgments, hemispheric equivalence, or interhemispheric transfer. No group differences in temporal judgments in any of the paired conditions were revealed. Both the ADHD and control groups demonstrated hemispheric equivalence for temporal judgments. Unexpectedly, the ADHD group demonstrated significantly faster interhemispheric transfer times when compared to the control group. The overall findings indicate that the reported deficit in time perception among individuals with ADHD may be restricted to tasks that involve response inhibition, reaction time, and/or motor movements (e.g., replicate durations of stimuli by pressing a lever).
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