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 http://clinicaltrials.gov/ct2/show/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...  Read more

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 http://clinicaltrials.gov/ct2/show/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.

References:

1. Benabid AL, Pollak P, Gervason C, et al. Long-term suppression of tremor by chronic stimulation of the ventral intermediate thalamic nucleus Lancet 1991: 337; 403-406 Abstract

2. Kuhn J, Grundler TO, Lenartz D, et al. Deep brain stimulation for psychiatric disorders Dtsch Arztebl Int 2010: 107; 105-113 Abstract

3. Smith GS, Laxton AW, Tang-Wai DF, et al. Increased Cerebral Metabolism After 1 Year of Deep Brain Stimulation in Alzheimer Disease. Arch Neurol 2012, in press

4. Laxton AW, Tang-Wai DF, McAndrews MP, et al. A phase I trial of deep brain stimulation of memory circuits in Alzheimer's disease Ann Neurol 2010: 68; 521-534 Abstract

5. Freund HJ, Kuhn J, Lenartz D, et al. Cognitive functions in a patient with Parkinson-dementia syndrome undergoing deep brain stimulation Arch Neurol 2009: 66; 781-785 Abstract

6. Barnikol TT, Pawelczyk NB, Barnikol UB, et al. Changes in apraxia after deep brain stimulation of the nucleus basalis Meynert in a patient with Parkinson dementia syndrome Mov Disord 2010: 25; 1519-1520

7. McIntyre CC, Savasta M, Walter BL, et al. How does deep brain stimulation work? Present understanding and future questions J Clin Neurophysiol 2004: 21; 40-50

8. Hardenacke K, Kuhn J, Lenartz D, et al. Stimulate or degenerate - Deep brain stimulation of the Nucleus basalis Meynert in Alzheimer’s dementia. World Neurosurg 2012, submitted.

View all comments by Katja Hardenacke
View all comments by Jens Kuhn