Verbal and visuospatial memory in lateral onset Parkinson disease: time is of the essence.

OBJECTIVE: This investigation sought to study immediate and delayed verbal and visuospatial recall in Parkinson disease (PD) patients with left hemibody (LHO) and right hemibody (RHO) onset of motor symptoms and to examine the role of mental processing speed in recall of this information. BACKGROUND: Research is mixed regarding material specific memory impairments in LHO and RHO PD. However, earlier research has not used a factorial approach in investigating material specific memory in LHO and RHO PD. We hypothesized that LHO PD patients would exhibit an increase in performance following the delayed verbal free recall trial and either decline or stability in performance on the delayed visuospatial free recall trial. The opposite pattern was hypothesized for RHO PD patients. METHOD: The Hopkins Verbal Learning Test-revised (HVLT-R) and the Brief Visuospatial Memory Test-revised (BVMT-R) were administered to a sample of 28 LHO PD patients and 36 RHO PD patients. The Stroop Color-word Test was administered as a measure of mental processing speed. RESULTS: The results indicated that the RHO group experienced a significant decline in performance on verbal free recall from the immediate to the delayed trials and a significant improvement in performance from the immediate to the delayed visuospatial free recall trials. Additionally, a significant negative correlation was found between mental processing speed and changes in recall from the immediate to the delayed conditions for the RHO group. CONCLUSIONS: These results indicate that the RHO PD group experienced a significant decline in verbal free recall and a significant improvement in visuospatial free recall from the immediate to the delayed trials and that the LHO PD patients experienced no significant changes. Further, mental processing speed appears to influence the recall of information from the immediate to the delayed conditions.

Anxiety affects working memory only in left hemibody onset Parkinson disease patients.

OBJECTIVE: This investigation sought to examine the potential moderating influence of heightened anxiety on working memory in Parkinson disease (PD) patients. Further, we wanted to determine whether this moderating influence of anxiety differentially affects PD patients with left hemibody (LBH) versus right hemibody (RHB) onset of motor symptoms. BACKGROUND: Research has examined the neurocognitive effects of depression in PD. However, a paucity of research has examined the effects of heightened anxiety in PD. We predicted that LHB PD patients with heightened anxiety would perform worse on a measure of working memory than RHB PD patients. METHOD: A total of 59 PD patients completed the state-trait anxiety inventory and were also administered the digit span subtest of the Wechsler Memory Scale-III. RESULTS: The results supported the hypotheses, indicating that the LHB PD patients with heightened anxiety performed significantly worse than the RHB PD patients with heightened anxiety and the LHB PD patients with low anxiety. CONCLUSIONS: These findings suggest that left hemibody onset PD patients may experience more disability in their activities of daily living. Future research should explore whether differences also exist between PD patients with and without the diagnosed anxiety disorders.

Greater motor improvement in right hemibody Parkinson's patients after dopaminergic medications.

Due to motor and neuropathological asymmetries, Parkinson's disease (PD) patients with right hemibody onset (RHO) of symptoms may experience greater benefit from dopaminergic enhancing medications, relative to patients with left hemibody onset (LHO). We investigated this possibility by measuring UPDRS scores of 20 PD patients with LHO and 13 patients with RHO, both prior and subsequent to taking dopaminergic enhancing medications. Following treatment, the motor score from the UPDRS improved for both groups of patients. However, PD patients with RHO experienced greater improvement in motor functioning following administration of dopaminergic enhancing medications than those with LHO.

Spreading activation of lexical-semantic networks in Parkinson's disease.

Although dopamine may act as a neuromodulator of spreading activation within semantic networks, this role of dopamine in lexical networks has not been investigated. Hence, we sought to investigate the effects of Parkinson's disease (PD), which is associated with dopamine depletion, on spreading activation in the lexical networks. Ten Parkinson's disease patients and 11 normal controls performed the controlled oral word association test and the average word frequency for their responses was calculated and used as an index of spreading activation. The PD patients exhibited a lower average word frequency, suggesting increased spreading activation, and a significant relationship between the strength of the initial activation and subsequent extent of spreading activation. Most patients were taking dopaminergic medication and future studies may benefit from examining the changes in spreading activation in lexical networks in PD patients on versus off medication or in healthy controls taking either a placebo or a dopaminergic medication. Although these alterations in lexical access might be related to the reduction of dopamine, one of the hallmarks of PD, these patients also have alterations of other neurotransmitter systems and further studies are needed to more clearly identify the role played by these neurotransmitter on lexical access.

Dopamine does not appear to affect mental rotation in Parkinson's disease.

OBJECTIVE: Patients with Parkinson's disease (PD) often have deficits with mental rotation (MR). The neuropathological factors underlying these deficits, however, remain to be elucidated. One hypothesis suggests that dopamine depletion in nigro-striatal systems adversely influences MR. Another hypothesis suggests that deterioration of cortical (fronto-temporo-parietal basal ganglia) networks that mediate this function are responsible for this deficit. The goal of this study was to test the dopamine hypothesis by determining if dopamine abstinence negatively influences MR performance. METHODS: Thirty three non-demented right-handed individuals with PD were assess for their ability to perform a pencil and paper MR test while "on" and "off" dopaminergic medications. Dopamine abstinence followed the typical overnight withdrawal procedures. RESULTS: No differences in mental rotation abilities were found between "on" and "off" dopaminergic medications. CONCLUSIONS: These results suggest that other neuropathological factors, such as cortical-basal ganglia neurodegeneration, or dysfunction of other neurotransmitters systems, might account for these cognitive deficits and future research will have to test these alternative hypotheses.

The prevalence of fatigue following deep brain stimulation surgery in Parkinson's disease and association with quality of life.

Fatigue is a common and disabling nonmotor symptom seen in Parkinson's disease (PD). While deep brain stimulation surgery (DBS) improves motor symptoms, it has also been associated with non-motor side effects. To date no study has utilized standardized instruments to evaluate fatigue following DBS surgery. Our objective was to determine the prevalence of fatigue following DBS surgery in PD its impact on quality of life and explore predictive factors. We recruited 44 PD subjects. At least one year following DBS placement, we administered the Fatigue Severity Scale (FSS), the Parkinson's Disease Questionnaire (PDQ-39), the Beck Depression Inventory, the Beck Anxiety Inventory, the UPDRS, and a neuropsychological battery. Fifty-eight percent of subjects had moderate to severe fatigue. Fatigue was significantly associated with quality of life, depression, and anxiety. Depression preoperatively was the only predictive factor of fatigue. Fatigue is common following DBS surgery and significantly impacts quality of life.

Anxiety and depression severity are related to right but not left onset Parkinson's disease duration.

Depression and anxiety have both been associated with relative left frontal hypoactivation and the motor symptoms of Parkinson's disease typically begin in a lateral or asymmetrical fashion. Hence, PD patients with right hemibody onset may experience heightened depression and anxiety. However, research is mixed regarding whether right or left hemibody onset PD is associated with elevated levels of depression and anxiety. This literature, though, has not considered the potential moderating variable of disease duration. We hypothesized that disease duration would be positively correlated with measures of depression and anxiety in right but not left hemibody onset PD patients. The results indicated that scores on the Geriatric Depression Scale, Beck Depression Inventory-II, and the State Trait Anxiety Scale - State correlated positively with disease duration, but only in the right hemibody onset group of PD patients. Thus, right hemibody onset PD is associated with more severe depressive and anxiety symptoms, but only when disease duration is considered.

Visual-spatial disembedding in Parkinson's disease.

Visual-spatial disembedding requires a person to visually scan the stimulus and allocate spatial selective attention to the locations of relevant stimuli. Parkinson's disease (PD) is often associated with visual-spatial deficits, but the influence of PD on disembedding is not entirely known. The goal of this study is to learn whether participants with PD have defective visuospatial disembedding and whether this defect responds to dopaminergic treatment. We also wanted to examine the relationship of disembedding with other cognitive processes and the different parkinsonian clinical symptoms. Participants were PD patients and matched controls. PD participants were tested "on" and "off" medications on the Hidden Patterns Test (HPT) and tests of frontal-executive functions. PD patients had difficulties in visual-spatial disembedding that were not related to medication status, illness duration or severity, or symptom presentation, but were related to other tasks requiring visual scanning in response to alterations in spatial allocation of attention. Lack of improvement with dopaminergic treatment suggests deficits in other neurotransmitter-neuromodulatory systems or degenerative processes in the frontal-striatal networks, cortex, or basal ganglia.