GBA mutations in Parkinson disease: earlier death but similar neuropathological features

BACKGROUND AND PURPOSE

Mutations in the glucocerebrosidase (GBA) gene are known to be a risk factor for Parkinson's disease (PD). Data on clinicopathological correlation are limited. The purpose of this study was to determine the clinicopathological findings that might distinguish PD cases with and without mutations in the GBA gene.

METHODS

Data from the Arizona Study of Aging and Neurodegenerative Disorders were used to identify autopsied PD cases that did or did not have a GBA gene mutation. Clinical and neuropathological data were compared.

RESULTS

Twelve PD cases had a GBA mutation and 102 did not. The GBA mutation cases died younger (76 vs. 81 years of age) but there was no difference in disease duration or clinical examination findings. No neuropathological differences were found in total or regional semi-quantitative scores for Lewy-type synucleinopathy, senile plaques, neurofibrillary tangles, white matter rarefaction or cerebral amyloid angiopathy scores.

CONCLUSIONS

In longitudinally assessed, autopsied PD cases, those with GBA mutations had a younger age at death but there was no evidence for clinical or neuropathological differences compared to cases without GBA mutations. Due to the small GBA group size, small differences cannot be excluded.

Medication dose reductions after pallidal versus subthalamic stimulation in patients with Parkinson's disease

OBJECTIVE

To compare the medication dose reduction between deep brain stimulation (DBS) of the globus pallidus interna (GPi) vs subthalamic nucleus (STN) in matched patients with Parkinson's disease (PD).

MATERIALS AND METHODS

Records of 12 patients with PD who underwent GPi-DBS at our institution from 2002 to 2008 were matched by pre-operative PD medication doses and pre-operative motor Unified Parkinson's Disease Rating Scale (UPDRS) scores to 12 cases of STN-DBS. PD medication doses were converted to levodopa equivalent doses (LEDs).

RESULTS

GPi and STN groups had similar mean pre-operative LEDs and motor UPDRS scores. At 6 months post-DBS, there was no significant difference in percent reduction in LEDs between the GPi (47.95%) and STN (37.47%) groups (P = 0.52). The mean post-operative 'medication off/stimulation on' motor UPDRS scores did not differ significantly between GPi (15.33) and STN (16.25) groups (P = 0.74). The mean percent reduction in motor UPDRS scores was also similar between GPi (58.44%) and STN (58.98%) patients (P = 0.94).

CONCLUSIONS

We conclude that in disease-matched patients with PD undergoing DBS, both GPi and STN may result in similar reduction in PD medication doses.

Quantitative EEG as a predictive biomarker for Parkinson disease dementia

OBJECTIVE

We evaluated quantitative EEG (QEEG) measures as predictive biomarkers for the development of dementia in Parkinson disease (PD). Preliminary work shows that QEEG measures correlate with current PD cognitive state. A reliable predictive QEEG biomarker for PD dementia (PD-D) incidence would be valuable for studying PD-D, including treatment trials aimed at preventing cognitive decline in PD.

METHODS

A cohort of subjects with PD in our brain donation program utilizes annual premortem longitudinal movement and cognitive evaluation. These subjects also undergo biennial EEG recording. EEG from subjects with PD without dementia with follow-up cognitive evaluation was analyzed for QEEG measures of background rhythm frequency and relative power in δ, , α, and β bands. The relationship between the time to onset of dementia and QEEG and other possible predictors was assessed by using Cox regression.

RESULTS

The hazard of developing dementia was 13 times higher for those with low background rhythm frequency (lower than the grand median of 8.5 Hz) than for those with high background rhythm frequency (p < 0.001). Hazard ratios (HRs) were also significant for > median bandpower (HR = 3.0; p = 0.004) compared to below, and for certain neuropsychological measures. The HRs for δ, α, and β bandpower as well as baseline demographic and clinical characteristics were not significant.

CONCLUSION

The QEEG measures of background rhythm frequency and relative power in the band are potential predictive biomarkers for dementia incidence in PD. These QEEG biomarkers may be useful in complementing neuropsychological testing for studying PD-D incidence.

Functional ability correlates with cognitive impairment in Parkinson's disease and Alzheimer's disease

BACKGROUND/AIMS

Previously we have shown that functional declines in Parkinson's disease (PD) and Alzheimer's disease (AD) correlate to global measures of cognitive decline. We now determine if the correlation between cognitive impairment and functional ability in PD is similar to that in AD using individual cognitive measures.

METHODS

93 PD subjects and 124 AD/MCI subjects underwent the Functional Assessment Staging (FAST), the Global Deterioration Scale (GDS), and a neuropsychological battery.

RESULTS

In PD subjects, the FAST and GDS correlated significantly with Rey Auditory Verbal Learning Test (AVLT), Controlled Oral Word Association (COWA), Animal Fluency, and Stroop but not with Clock Draw or Judgment Line Orientation (JLO). In AD/MCI subjects, FAST and GDS correlated with all neuropsychological components except Stroop. In the AD/MCI group, the UPDRS significantly correlated with the FAST, GDS, MMSE, and all neuropsychological parameters except the Stroop. In the PD group, the motor UPDRS significantly correlated significantly with FAST, GDS, MMSE and all neuropsychological parameters except Digit Span, Stroop, Clock Draw and JLO.

CONCLUSIONS

Similar to AD, functional decline in PD correlates with multiple measures of cognitive impairment. Some differences between PD and AD may be explained by the influence of motor disability and declines in visuospatial function in PD.

Both early and late cognitive dysfunction affects the electroencephalogram in Parkinson's disease

We sought to define quantitative electroencephalographic (EEG) measures as biomarkers of both early and late cognitive decline in Parkinson's disease (PD). PD subjects classified as cognitively normal (PD-CogNL), mild cognitive impairment (PD-MCI), and dementia (PD-D) were studied. Cognitive status and neuropsychological testing was correlated with background rhythm and frequency band EEG power across five frequency bands. We conclude that global EEG measures have potential use as biomarkers in the study of both early and late cognitive deterioration in PD, including for evaluating its treatment. PD-MCI has mean quantitative EEG characteristics that represent an intermediate electrophysiological state between PD-CogNL and PD-D.