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Smith GS, Laxton AW, Tang-Wai DF, McAndrews MP, Diaconescu AO, Workman CI, Lozano AM. Increased Cerebral Metabolism After 1 Year of Deep Brain Stimulation in Alzheimer Disease. Arch Neurol. 2012 May 7; PubMed.
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Baylor College of Medicine
Dr. Lozano’s study demonstrating increased cerebral glucose metabolism one year following deep-brain stimulation for Alzheimer’s disease is an exciting advancement in the development of a treatment for the cognitive and neuropsychiatric symptoms of AD. The findings of a relationship between improvements in outcome (although minor) and increased metabolism strengthens the researchers' argument that a larger study is needed to further evaluate the efficacy of this intervention. It should be noted that in this very small sample, the patients were younger and less cognitively impaired than the majority of AD patients seen in clinical populations. However, as a proof-of-concept and tolerability study, these findings provide the impetus needed for further investigation. This avenue of research will require a large, well-controlled, and thoroughly described investigation with both short- and long-term safety and efficacy outcomes in a sample that can be generalized to a wider AD population prior to it being offered as a therapeutic intervention.
University of Cologne
Since the end of the 1980s, deep-brain stimulation (DBS) has substantially expanded the therapeutically possibilities of treating Parkinson’s disease (1). DBS refers to a complex neuromodulative procedure, which implies the stereotactical implantation of two electrodes into defined target structures of the brain. The success story told by DBS in the field of movement disorders, the minimally invasive surgery and the rare and usually very minor side effects, suggest that the ambitions of applying DBS to other neurological and psychiatric indications will be more quickly fulfilled in the future (2). And indeed, in the last three years two groups (3-6) (see also NCT01094145) employed DBS has been used with the aim of improving cognitive abilities in patients with dementia.
Despite many years of experience with DBS, the therapeutic mechanisms are not yet completely understood. There are various actions being discussed, since, on the neuronal level, excitatory and inhibitory mechanisms are assumed to play a part (7). In the case of applying DBS to Alzheimer’s dementia there is hope that the cognitive abilities of the patients can be stabilized and ideally neuroprotective effects promoted—for example through the induction of NGF-synthesis (8) or changes in cerebral blood supply. This recent investigation by Smith and colleagues seems to support those hypothesis concerning the working mechanism of DBS. Patients with mild to moderate AD were treated with DBS in the fornix and demonstrated, after one year of stimulation, increased cerebral metabolism in cortical-subcortical and cortical-hippocampal regions. The increased metabolism correlated positively with global cognition, memory functioning, and quality of life. The published results encourage further research into this field to evaluate the efficacy of DBS in patients with AD.
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Smith GS, Laxton AW, Tang-Wai DF, McAndrews MP, Diaconescu AO, Workman CI, Lozano AM. Increased Cerebral Metabolism After 1 Year of Deep Brain Stimulation in Alzheimer Disease. Arch Neurol. 2012 May 7; PubMed.
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McIntyre CC, Savasta M, Walter BL, Vitek JL. How does deep brain stimulation work? Present understanding and future questions. J Clin Neurophysiol. 2004 Jan-Feb;21(1):40-50. PubMed.
Hardenacke K, Kuhn J, Lenartz D, Maarouf M, Mai JK, Bartsch C, Freund HJ, Sturm V. Stimulate or Degenerate: Deep Brain Stimulation of the Nucleus Basalis Meynert in Alzheimer Dementia. World Neurosurg. 2012 Dec 12; PubMed.
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