Weight Loss in Parkinson's Disease: No Evidence for Role of Small Intestinal Bacterial Overgrowth

BACKGROUND AND OBJECTIVE

Weight loss and small intestinal bacterial overgrowth (SIBO) are common in Parkinson's disease (PD). We aimed to study the relationship between weight loss and SIBO in PD.

METHODS

This was a cross-sectional study with a prospective, interventional component. Consecutive patients seen in the PD clinic who agreed to participate underwent extensive history, movement exam, SIBO breath testing and answered questionnaires. A subset of those in the weight loss group were treated with rifaximin for 14 days and returned 3 months later for an assessment of their weight, GI symptoms, quality of life and SIBO status. All analyses were adjusted for age and disease duration.

RESULTS

Fifty-one patients participated in the study; 37 without weight loss and 14 with weight loss. Total energy intake including the distribution of macronutrient intake was similar between groups while physical activity was less in those with weight loss. PD severity scores did not differ between groups; however, PD-specific quality of life scores were significantly worse for the summary index and the subscales of emotional well-being, social support and communication. The prevalence of constipation, dyspepsia and abdominal pain/discomfort was higher in those with weight loss. The prevalence of SIBO was 14% in the weight loss group and was not different between groups. Eight PD patients with weight loss were treated with rifaximin; no significant change in GI symptoms, quality of life or weight was seen 3 months later.

CONCLUSION

Although a number of differences were identified in quality of life and gastrointestinal symptoms between groups with and without weight loss, SIBO was not associated with weight loss in patients with PD. Given the exploratory nature and small number of patients with weight loss, however, further study is suggested.

Personality Changes During the Transition from Cognitive Health to Mild Cognitive Impairment

BACKGROUND/OBJECTIVES

Behavioral problems in individuals with Alzheimer's disease (AD) impose major management challenges. Current prevention strategies are anchored to cognitive outcomes, but behavioral outcomes may provide another, clinically relevant opportunity for preemptive therapy. We sought to determine whether personality changes that predispose to behavioral disorders arise during the transition from preclinical AD to mild cognitive impairment (MCI).

DESIGN

Longitudinal observational cohort study.

SETTING

Academic medical center.

PARTICIPANTS

Members of an apolipoprotein E (APOE) ɛ4 genetically enriched cohort of Maricopa County residents who were neuropsychiatrically healthy at entry (N = 277). Over a mean interval of 7 years, 25 who developed MCI and had the Neuroticism, Extraversion, and Openness Personality Inventory-Revised (NEO-PI-R) before and during the MCI transition epoch were compared with 252 nontransitioners also with serial NEO-PI-R administrations.

INTERVENTION

Longitudinal administration of the NEO-PI-R and neuropsychological test battery.

MEASUREMENTS

Change in NEO-PI-R factor scores (neuroticism, extraversion, openness, agreeableness, conscientiousness) from entry to the epoch of MCI diagnosis or an equivalent follow-up duration in nontransitioners.

RESULTS

NEO-PI-R neuroticism T-scores increased significantly more in MCI transitioners than in nontransitioners (mean 2.9, 95% confidence interval (CI) = 0.9-4.9 vs 0, 95% CI = -0.7-0.7, P = .02), and openness decreased more in MCI transitioners than in nontransitioners (-4.8, 95% CI = -7.3 to -2.4 vs -1.0, 95% CI = -1.6 to -0.4, P < .001). Concurrent subclinical but statistically significant changes in behavioral scores worsened more in MCI transitioners than nontransitioners for measures of depression, somatization, irritability, anxiety, and aggressive attitude.

CONCLUSION

Personality and subclinical behavioral changes begin during the transition from preclinical AD to incident MCI and qualitatively resemble the clinically manifest behavioral disorders that subsequently arise in individuals with frank dementia.

The neuropsychology of normal aging and preclinical Alzheimer's disease

OBJECTIVE

A National Institute on Aging-sponsored work group on preclinical Alzheimer's disease (AD) articulated the need to characterize cognitive differences between normal aging and preclinical AD.

METHODS

Seventy-one apolipoprotein E (APOE) ε4 homozygotes, 194 ε3/ε4 heterozygotes, and 356 ε4 noncarriers age 21 to 87 years who were cognitively healthy underwent neuropsychological testing every 2 years. Longitudinal trajectories of test scores were compared between APOE subgroups.

RESULTS

There was a significant effect of age on all cognitive domains in both APOE ε4 carriers and noncarriers. A significant effect of APOE ε4 gene dose was confined to the memory domain and the Dementia Rating Scale. Cross-sectional comparisons did not discriminate the groups.

CONCLUSIONS

Although cognitive aging patterns are similar in APOE ε4 carriers and noncarriers, preclinical AD is characterized by a significant ε4 gene dose effect that impacts memory and is detectable longitudinally. Preclinical neuropsychological testing strategies should emphasize memory-sensitive measures and longitudinal design.

Cerebrovascular risk factors and preclinical memory decline in healthy APOE ε4 homozygotes

OBJECTIVE

To characterize the effects of cerebrovascular (CV) risk factors on preclinical memory decline in cognitively normal individuals at 3 levels of genetic risk for Alzheimer disease (AD) based on APOE genotype.

METHODS

We performed longitudinal neuropsychological testing on an APOE ε4 enriched cohort, ages 21-97. The long-term memory (LTM) score of the Auditory Verbal Learning Test (AVLT) was the primary outcome measure. Any of 4 CV risk factors (CVany), including hypercholesterolemia (CHOL), prior cigarette use (CIG), diabetes mellitus (DM), and hypertension (HTN), was treated as a dichotomized variable. We estimated the longitudinal effect of age using statistical models that simultaneously modeled the cross-sectional and longitudinal effects of age on AVLT LTM by APOE genotype, CVany, and the interaction between the two.

RESULTS

A total of 74 APOE ε4 homozygotes (HMZ), 239 ε4 heterozygotes (HTZ), and 494 ε4 noncarriers were included. APOE ε4 carrier status showed a significant quadratic effect with age-related LTM decline in all models as previously reported. CVany was associated with further longitudinal AVLT LTM decline in APOE ε4 carriers (p=0.02), but had no effect in noncarriers. When ε4 HTZ and HMZ were considered separately, there was a striking effect in HMZ (p<0.001) but not in HTZ. In exploratory analyses, significant deleterious effects were found for CIG (p=0.001), DM (p=0.03), and HTN (p=0.05) in APOE ε4 carriers only that remained significant only for CIG after correction for multiple comparisons.

CONCLUSION

CV risk factors influence age-related memory decline in APOE ε4 HMZ.

Clinical and electrodiagnostic findings in copper deficiency myeloneuropathy

INTRODUCTION

Copper deficiency is an increasingly recognised cause of neurological impairment. This retrospective review highlights clinical and electrodiagnostic findings in patients diagnosed at our institution with copper deficiency.

METHODS

Clinical, radiographic and electrodiagnostic findings were reviewed in patients with evidence of copper deficiency. Patients with other potential causes of myelopathy or neuropathy were excluded.

RESULTS

The predominant clinical feature in all six patients was a sensory ataxia, resulting in marked gait unsteadiness. Nerve conduction studies and needle EMG were performed in all patients and revealed a mild to moderate distal, axonal, sensorimotor peripheral neuropathy. Median and tibial somatosensory evoked potentials were abnormal in all five patients in which it was performed, showing impaired conduction in central or proximal peripheral somatosensory pathways.

CONCLUSIONS

This pattern of electrodiagnostic findings suggests that impairment in somatosensory pathways demonstrated by somatosensory evoked potential testing is the main cause of the sensory ataxia in patients with copper deficiency.

Cognitive domain decline in healthy apolipoprotein E epsilon4 homozygotes before the diagnosis of mild cognitive impairment

BACKGROUND

Memory declines more rapidly with age in apolipoprotein E (APOE) epsilon4 carriers than in APOE epsilon4 noncarriers, and APOE epsilon4 homozygotes' cognitive performances correlate with stressors. These changes could represent presymptomatic disease in some, despite their youth.

OBJECTIVE

To show that presymptomatic APOE epsilon4 homozygotes experience greater psychometric decline at a younger age than APOE epsilon4 heterozygotes and noncarriers before the diagnosis of mild cognitive impairment (MCI) and Alzheimer disease (AD).

DESIGN

Prospective observational study

SETTING

Academic medical center.

PARTICIPANTS

A total of 43 APOE epsilon4 homozygotes, 59 APOE epsilon4 heterozygotes, and 112 APOE epsilon4 noncarriers aged 50 to 69 years were cognitively healthy and matched at entry according to age, educational level, and sex.

INTERVENTION

Neuropsychological battery given every 2 years.

MAIN OUTCOME MEASURES

Predefined test and cognitive domain decline criteria applied to consecutive epochs.

RESULTS

Of 214 participants, 48 showed no decline on any test, 126 showed decline on only 1 test in 1 or more domains, and 40 showed decline on 2 or more tests in 1 or more domains. Cognitive domain decline occurred in 4 of 10 APOE epsilon4 homozygotes 60 years and older at entry (40.0%) compared with 5 of 66 APOE epsilon4 heterozygotes and noncarriers (7.6%) (P = .02) and was more predictive of subsequent decline than nondomain decline (17 of 24 [70.8%] vs 29 of 70 [41.4%]; P = .01). Decline on any memory test was predictive of further decline (P < .001), as was memory domain decline (P = .006) in all genetic subgroups. Seven participants developed MCI (in 6) or AD (in 1), of whom 5 were APOE epsilon4 homozygotes (P = .008). Retrospective comparison showed that those who experienced multidomain, memory, and language domain decline had lower spatial and memory scores at entry than those who experienced no decline.

CONCLUSIONS

APOE epsilon4 homozygotes in their 60s have higher rates of cognitive domain decline than APOE epsilon4 heterozygotes or noncarriers before the diagnosis of MCI and AD, thus confirming and characterizing the existence of a pre-MCI state in this genetic subset.

Value of the oral glucose tolerance test in the evaluation of chronic idiopathic axonal polyneuropathy

BACKGROUND

An underlying cause is found in only 7% to 30% of patients with chronic idiopathic axonal polyneuropathy (CIAP). Diabetes mellitus, inherited disorders, toxin exposure, and primary amyloidosis are the most common identified causes of sensory neuropathies affecting both large and small myelinated fibers. Undiagnosed impaired fasting glucose metabolism has been associated with CIAP at a higher frequency rate than in the general population. This increased prevalence rate was identified using the 2-hour oral glucose tolerance test (2h-OGTT) and a previous version of the American Diabetes Association (ADA) guidelines.

OBJECTIVES

To determine the prevalence of abnormal fasting glucose metabolism in patients with CIAP and to compare the value of determining fasting plasma glucose levels using revised (2003) ADA criteria with the 2h-OGTT for predicting abnormal fasting glucose metabolism.

PATIENTS

In this 24-month retrospective study, 100 consecutive patients were identified with no known cause for CIAP, including diabetes mellitus, between January 2003 and January 2005. All had both a fasting plasma glucose test and a 2h-OGTT in addition to a complete neurological examination. Neurophysiological studies, computer-assisted sensory examination, and quantitative sudomotor axonal reflex testing were used to classify CIAP into subtypes according to nerve fiber involvement.

RESULTS

The prevalence of undiagnosed abnormal fasting glucose metabolism was found to be nearly 2-fold higher (62%) in patients with CIAP than in similar age-matched general population groups (33%). Using the 2003 revised ADA criteria, 39 patients (39%) had abnormal fasting plasma glucose metabolism (36 with impaired fasting glucose, 3 with diabetes mellitus), while the 2h-OGTT provided an even higher diagnostic rate of 62% (62 patients; P<.001) of impaired fasting glucose metabolism (38 with impaired glucose tolerance, 24 with diabetes mellitus). The abnormal glucose metabolism rates were found to be similar across the 3 subtypes (sensorimotor, pure sensory, and small-fiber neuropathy) of CIAP (P = .60, .72, and .61).

CONCLUSIONS

This study adds to emerging evidence that abnormal glucose metabolism may be a risk factor for CIAP. Even with revised (2003) ADA criteria, the 2h-OGTT provides additional diagnostic information to the health care professional in the evaluation of CIAP. Subtypes of CIAP are equally likely to have abnormal glucose metabolism.