Biomedical subjects

Christopher I Higginson

Publications and source records attributed to Christopher I Higginson.

5 recordsLinked to original sources

PubMed2005

Dopamine dependency of cognitive switching and response repetition effects in Parkinson's patients.

A group of people with Parkinson's disease and a group of matched controls were tested on a task involving a switch between perceptual dimensions. Patients were tested both 'on' and 'off' their normal medication cycles. Stimuli appeared in pairs for each trial, with each stimulus consisting of a color and a shape. One dimension of color and one of shape were mapped to each of two response keys. A cue was presented concurrently with each stimulus to indicate whether to respond on the basis of color or shape, following procedures developed by Hayes et al. [Hayes, A.E., Davidson, M.C., Keele, S.W., and Rafal, R.D. (1998). Toward a functional analysis of the basal ganglia. Journal of Cognitive Neuroscience, 10, 178-198]. Replicating previous literature, abnormally large switch costs were observed in patients who were off their normal medication cycles. A novel finding was that patients in the 'on' state demonstrated a slight reversal of switch costs. Also novel, reaction time (RT) costs associated with switching between response keys, and interactions between response switching and task switching were influenced predominantly by on-off dopamine manipulations. It is concluded that abnormal task switching costs and response repetition effects likely reflect impairments of activation and inhibition, and both effects are dopamine-dependent.

Case-Control Studies↗

PubMed2005

Recognition memory in Parkinson's disease with and without dementia: evidence inconsistent with the retrieval deficit hypothesis.

Parkinson's disease (PD) has been associated with a pattern of performance on memory tests in which free recall is impaired but recognition and cued recall are intact, indicating problems with memory retrieval. Recent findings suggest that PD patients exhibit deficits in recognition as well as free recall, however. The current study set out to provide clear evidence that recognition and cued recall are not intact in PD. Ninety-nine idiopathic PD patients were administered the California Verbal Learning Test and their performance was compared to a well-matched normative sample. A profile analysis revealed that nondemented patients exhibited deficits on measures of cued recall and delayed recognition that were similar in magnitude to that of free recall. This was also the case for the cued recall deficits exhibited by demented patients; however, in this group recognition was worse than free recall. In both groups poor recognition appeared due to an elevated number of false positive errors. These results are inconsistent with the retrieval deficit hypothesis but support the notion that PD memory problems are secondary to prefrontal dysfunction.

Aged↗

PubMed2003

The relationship between executive function and verbal memory in Parkinson's disease.

A growing body of evidence suggests that the various cognitive symptoms found in Parkinson's disease (PD) are secondary to executive dysfunction. Studies addressing this possibility for memory impairment specifically have not included measures of working memory nor have they ruled-out potential mediating variables such as overall level of cognitive impairment or depression. The purpose of this study was to include measures of these variables in determining the relationship between multiple aspects of executive function and delayed verbal recall in 32 idiopathic PD patients. Results were consistent with the original hypothesis and further suggest that working memory is a key factor in recall memory and may mediate the relationship between other executive measures and recall in PD.

Cognition Disorders↗

PubMed2002

Relationship between coping, cognitive dysfunction and depression in multiple sclerosis.

Given its relatively high prevalence, one possible source of stress for patients with multiple sclerosis (MS) is cognitive dysfunction. The authors' study was guided by a new theoretical model suggesting that cognitive dysfunction in MS may be most likely to lead to depression when patients use high levels of avoidance coping and/or low levels of active coping. To test this model, 55 patients with definite MS were administered a neuropsychological battery and measures of depression and coping. Consistent with predictions, regression analyses showed that coping significantly moderated the relationship between cognitive dysfunction and depression. Specifically, cognitive dysfunction was most likely to be associated with depression when patients used either high levels of avoidance or low levels of active coping. Implications of these data for clinical applications and for our theoretical conceptualization are discussed and limitations of the model explored.

Adaptation, Psychological↗

PubMed2002

Contributing factors to depressed mood in Multiple Sclerosis.

By applying the behavioral theory of Lewinsohn et al. [1985. An integrative theory of depression. In: S. Reiss, & R. R. Bootzin (Eds.), Theoretical issues in behavior therapy (pp. 331-359). San Diego, CA: Academic Press.] to multiple sclerosis (MS), it was hypothesized that physical disability, fatigue, and psychosocial dysfunction would be significantly predictive of depressed mood in MS patients. Seventy-six MS patients completed the following measures: the Sickness Impact Profile (SIP), the Fatigue Impact Scale (FIS), and the mood subscale from the Chicago Multiscale Depression Inventory (CMDI). Structural equation modeling revealed that physical disability and fatigue were indirectly predictive of depressed mood via their effects on recreational functioning. Fatigue also had a direct effect on mood. If reductions in recreational activities actually cause decrements in mood, depressed mood in MS may be treatable by helping patients identify recreational activities that they can enjoy regardless of physical or fatigue-related difficulties.

Journal Article↗