[Cognitive dysfuctions associated with essential tremor and Parkinson's disease].

Abstract

To explore the incidence of cognitive dysfunction and associated factors in 62 essential tremor (ET) cases, 60 normal controls and 61 Parkinson's disease (PD) cases. A total of 62 ET and 61 PD patients from September 2009 to September 2013 were recruited from our outpatient clinic. ET patients received the Tremor Rating Scale for Tremor-motor examination (items 1-15 of rating scale) while 61 PD patients were examined with the Unified Parkinson's Disease Rating Scale (UPDRS)-motor examination and a modified Hoehn and Yahr scale for staging disorder severity. All participants completed Montreal Cognitive Assessment (MoCA) Beijing version for measuring cognitive functions. And depression was evaluated by the Hamilton Depression Scale (HAMD). The serum levels of uric acid were tested. A MoCA score <26 (at least mildly cognitive) was observed in 14 (23.3%) normal controls, compared to 24 (38.7%) ET cases and 27 (44.3%) PD cases (P = 0.045 when comparing all 3 groups, and P = 0.532 when comparing ET and PD). The factor scores of visual space/execution were 4.1 ± 1.0, 3.8 ± 1.1 and 3.2 ± 1.6 in normal controls, ET and PD patients, the factor scores of naming 2.9 ± 0.4, 2.8 ± 0.6 and 2.3 ± 0.8 in control, ET and PD patients, the factor scores of delay memory 3.9 ± 0.9, 2.7 ± 1.3 and 2.5 ± 1.7 in control, ET and PD patients. Statistical differences existed in visual space/execution, naming and delay memory (P < 0.05) among 3 groups. Yet there were no statistical differences in attention, language, abstract and directional among 3 groups. Statistical differences existed in visual space/execution and naming between ET and PD patients (P < 0.05). PD cases had the lowest visual space/execution score, followed by ET (intermediate) and highest scores in controls (P < 0.05). In ET patients, cognitive scores were correlated with serum levels of uric acid, education, tremor Rating Scale for Tremor-motor subscale score and depression levels (r = 0.589, P = 0.000; r = 0.449, P = 0.010; r = 0.452, P = 0.009; r = 0.466, P = 0.025). In PD patients, cognitive scores correlated with serum levels of uric acid, education, score of UPDRS-III and depression levels (r = 0.694, P = 0.000; r = 0.614, P = 0.000; r = 0.604, P = 0.000; r = 0.376, P = 0.000). The incidence of cognition is higher in ET and PD. There were no significant inter-group differences for cognition frequency. The most frequently endorsed symptoms were poor visual spatial ability, execution disturbance and delayed recall disorders. Some connition scores in ET were intermediate between those of PD cases and normal controls. Thus a mild form of connition dysregulation may be present in ET. The degree of cognition symptoms is correlated with serum levels of uric acid, education and serious motor.