Striatal dopamine transporter function in dementia with Lewy bodies and Parkinson's disease.

The aim of this study was to compare parkinsonian features and loss of striatal dopamine transporter (DAT) function in patients with dementia with Lewy bodies (DLB) and Parkinson's disease (PD), matched for age and disease duration. Twenty patients with DLB. 24 PD patients and 10 matched controls were examined with SPET using a dual-head camera and the dopamine-transporter ligand 123I-beta-CIT (148 MBq). Moreover, in a subgroup of patients (16 DLB and 20 PD patients), subscores of the Unified Parkinson's Disease Rating Scale (UPDRS)-motor examination (ME) subscale were obtained during "practical off", i.e. 12 h following withdrawal of antiparkinsonian therapy. Compared with controls, striatal/cerebellar (S/C) ratios of DAT binding were significantly reduced in both DLB and PD, deficits being more marked in DLB patients (controls 7.2 +/- 1.2, DLB 3.3 +/- 1, PD 4.2 +/- 1.4; means +/- SD). The side-to-side differences in the S/C ratios were lower in the DLB group and the controls than in PD patients (0.4 +/- 0.4. 0.2 +/- 0.2 and 0.6 +/- 0.3, respectively, P<0.05). The total UPDRS-ME scores during practical-off were significantly higher in the DLB than in the PD group (41.2 +/- 12.7 vs 26.6 +/- 15.3, P<0.01). The side-to-side differences of the summed UPDRS extremity subscores were smaller in the DLB than in the PD group (2.2 +/- 2.3 vs 7.4 +/- 3.9, P<0.0001). Our findings suggest that parkinsonism evolves largely symmetrically and progresses more rapidly with more severe loss of striatal dopamine transporter function in DLB compared to PD. Whether these findings are helpful in the differential diagnosis of DLB and PD needs to be examined in further studies.

Beneficial effects of amantadine on L-dopa-induced dyskinesias in Parkinson's disease.

L-Dopa-induced dyskinesias constitute a challenge to the management of advanced Parkinson's disease. According to recent reports, treatment with the NMDA receptor antagonist amantadine may significantly diminish L-dopa-induced dyskinesias. In the present study, the effect of amantadine on L-dopa-induced dykinesias was assessed in a 5-week, double-blind crossover trial. Dyskinesia severity as assessed following oral L-dopa challenges and by self-scoring dyskinesia diaries were reduced approximately 50% after amantadine treatment compared with baseline or placebo phases. Similarly, dyskinesia assessments on the Unified Parkinson's Disease Rating Scale, part IV (items 32 and 33) also revealed significant improvement after treatment with amantadine. The magnitude of the L-dopa motor response to oral challenges was not different after amantadine or placebo treatment, and there was no significant reduction of daily off-time when patients received active treatment. These results confirm previous observations concerning the antidyskinetic potential of amantadine.

Depression in Parkinson's disease: impediments to recognition and treatment options.

By some estimates, nearly half of patients with PD also suffer depression. Because features of PD frequently overlap with typical manifestations of major affective disorder (or mild dysthymia), both diagnosis and treatment of this comorbidity are challenging. Some of these interactive features include cognitive and speech deficits and impairments in emotional expression (e.g., PD-related facial masking) or processing. Parkinsonian depression probably is caused by an independent abnormality rather than as a maladaptive response to disease, in that the degree of depression is not correlated with PD severity. Prognostically, depressive features (e.g., introversion, inflexibility) may represent a subtle premorbid state heralding the onset of PD or an accelerated cognitive decline thereafter. Therapeutic mainstays for parkinsonian depression include psychosocial counseling at the time of PD diagnosis (and during advanced stages of PD) as well as appropriate medication regimens, the relative clinical efficacy of which remain a matter of ongoing clinical inquiry: levodopa, dopamine agonists, selegilene, tricyclic antidepressants, and selective serotonin reuptake inhibitors). This review formulates a rational treatment algorithm to assist in clinical management of parkinsonian depression, an enormously complex clinical entity.

Dopamine D4 receptor polymorphism and idiopathic Parkinson's disease.

Patients with idiopathic Parkinson's disease (IPD) are described as having markedly decreased novelty seeking characteristics. Since recent publications suggest an association between the dopamine D4 receptor polymorphism and novelty seeking, we investigated this polymorphism in a group of 122 patients with IPD and 127 healthy control subjects. We found similar allele and genotype frequencies in both groups and no association with the age of onset of symptoms. Therefore, the dopamine D4 receptor polymorphism does not confer genetic susceptibility to IPD and cannot explain the decreased novelty seeking in IPD patients.