A phase I trial of deep brain stimulation of memory circuits in Alzheimer's disease.

OBJECTIVE: Alzheimer disease (AD) is characterized by functional impairment in the neural elements and circuits underlying cognitive and memory functions. We hypothesized that fornix/hypothalamus deep brain stimulation (DBS) could modulate neurophysiological activity in these pathological circuits and possibly produce clinical benefits. METHODS: We conducted a phase I trial in 6 patients with mild AD receiving ongoing medication treatment. Patients received continuous stimulation for 12 months. Three main lines of investigation were pursued including: (1) mapping the brain areas whose physiological function was modulated by stimulation using standardized low-resolution electromagnetic tomography, (2) assessing whether DBS could correct the regional alterations in cerebral glucose metabolism in AD using positron emission tomography (PET), and 3) measuring the effects of DBS on cognitive function over time using clinical scales and instruments. RESULTS: DBS drove neural activity in the memory circuit, including the entorhinal, and hippocampal areas and activated the brain's default mode network. PET scans showed an early and striking reversal of the impaired glucose utilization in the temporal and parietal lobes that was maintained after 12 months of continuous stimulation. Evaluation of the Alzheimer's Disease Assessment Scale cognitive subscale and the Mini Mental State Examination suggested possible improvements and/or slowing in the rate of cognitive decline at 6 and 12 months in some patients. There were no serious adverse events. INTERPRETATION: There is an urgent need for novel therapeutic approaches for AD. Modulating pathological brain activity in this illness with DBS merits further investigation.

An exploration of cognitive subgroups in Alzheimer's disease.

Heterogeneity is observed in the patterns of cognition in Alzheimer's disease (AD). Such heterogeneity might suggest the involvement of different etiological pathways or different host responses to pathology. A total of 627 subjects with mild/moderate AD underwent cognitive assessment with the Mini-Mental State Examination (MMSE) and the Dementia Rating Scale-2 (DRS-2). Latent class analysis (LCA) was performed on cognition subscale data to identify and characterize cognitive subgroups. Clinical, demographic, and genetic factors were explored for association with class membership. LCA suggested the existence of four subgroups; one group with mild and another with severe global impairment across the cognitive domains, one group with primary impairments in attention and construction, and another group with primary deficits in memory and orientation. Education, disease duration, age, Apolipoprotein E-epsilon4 (APOE epsilon4) status, gender, presence of grasp reflex, white matter changes, and early or prominent visuospatial impairment were all associated with class membership. Our results support the existence of heterogeneity in patterns of cognitive impairment in AD. Our observation of classes characterized by predominant deficits in attention/construction and memory respectively deserves further exploration as does the association between membership in the attention/construction class and APOE epsilon4 negative status.

Candidate single-nucleotide polymorphisms from a genomewide association study of Alzheimer disease.

OBJECTIVE: To identify single-nucleotide polymorphisms (SNPs) associated with risk and age at onset of Alzheimer disease (AD) in a genomewide association study of 469 438 SNPs. DESIGN: Case-control study with replication. SETTING: Memory referral clinics in Canada and the United Kingdom. PARTICIPANTS: The hypothesis-generating data set consisted of 753 individuals with AD by National Institute of Neurological and Communicative Diseases and Stroke/Alzheimer's Disease and Related Disorders Association criteria recruited from 9 memory referral clinics in Canada and 736 ethnically matched control subjects; control subjects were recruited from nonbiological relatives, friends, or spouses of the patients and did not exhibit cognitive impairment by history or cognitive testing. The follow-up data set consisted of 418 AD cases and 249 nondemented control cases from the United Kingdom Medical Research Council Genetic Resource for Late-Onset AD recruited from clinics at Cardiff University, Cardiff, Wales, and King's College London, London, England. MAIN OUTCOME MEASURES: Odds ratios and 95% confidence intervals for association of SNPs with AD by logistic regression adjusted for age, sex, education, study site, and French Canadian ancestry (for the Canadian data set). Hazard ratios and 95% confidence intervals from Cox proportional hazards regression for age at onset with similar covariate adjustments. RESULTS: Unadjusted, SNP RS4420638 within APOC1 was strongly associated with AD due entirely to linkage disequilibrium with APOE. In the multivariable adjusted analyses, 3 SNPs within the top 120 by P value in the logistic analysis and 1 in the Cox analysis of the Canadian data set provided additional evidence for association at P< .05 within the United Kingdom Medical Research Council data set: RS7019241 (GOLPH2), RS10868366 (GOLPH2), RS9886784 (chromosome 9), and RS10519262 (intergenic between ATP8B4 and SLC27A2). CONCLUSIONS: Our genomewide association analysis again identified the APOE linkage disequilibrium region as the strongest genetic risk factor for AD. This could be a consequence of the coevolution of more than 1 susceptibility allele, such as APOC1, in this region. We also provide new evidence for additional candidate genetic risk factors for AD that can be tested in further studies.

Simulation of brain death from fulminant de-efferentation.

BACKGROUND: Guillain-Barré syndrome (GBS) classically presents with a subacutely evolving areflexic paralysis, with typical laboratory findings of elevated cerebrospinal fluid protein and abnormal nerve conduction studies. There is now an increasing recognition of GBS variants that differ in clinical presentation, prognosis, electrophysiology and presumed pathogenesis. Fulminant cases of GBS have been reported in which a rapid deterioration evolves to a clinical state resembling "brain death". METHODS: A retrospective analysis of two such cases of fulminant neuropathy are described, that includes the clinical course, electrophysiology and neuropathology where available. RESULTS: We describe two patients that presented with a rapid course of neurological deterioration, lapsing into what resembled a "clinically brain-dead" state that was subsequently ascribed to a fulminant polyneuropathy. Investigations (electrophysiological, pathological) and the clinical course suggested an axonal neuropathy. CONCLUSIONS: A fulminant neuropathy can result in a clinical state resembling "brain death" through diffuse de-efferentation. Although generally attributed to aggressive demyelination with secondary axonal degeneration, a primary axonopathy can also lead to a similar clinical presentation.

J. Clifford Richardson and 50 years of progressive supranuclear palsy.

OBJECTIVE: To trace the historical events leading to Richardson's clinical description of progressive supranuclear palsy (PSP) in the context of subsequent observations of its clinical heterogeneity and pathologic overlap with other tauopathies. BACKGROUND: Fifty years ago, Canadian neurologist J. Clifford Richardson identified patients in Toronto with a syndrome of supranuclear vertical gaze palsy, pseudobulbar palsy, axial rigidity-in-extension, and cognitive impairment. In his seminal description, Richardson predicted that further clinicopathologic observations would broaden the clinical syndrome and that this was unlikely to be a disorder restricted to the Toronto region. METHODS: The recollections of two of Richardson's contemporaries and archival material from his time were used as primary materials. Publications that follow the evolution of his observations were examined. RESULTS: Recent factor analysis of pathologically verified PSP cases has confirmed the accuracy and uniformity of the original classic clinical description of PSP and vindicated Richardson's prediction of clinical variants. Most notably, a presentation with Parkinson syndrome and absent gaze palsy has been identified, with less severe PSP-tau pathology. CONCLUSIONS: In recognition of his seminal observations, we propose that the classic clinical presentation of PSP-tau pathology be renamed Richardson's disease, and that the commonest clinical variant be termed PSP-parkinsonism.