What Are the Downsides and Risks of Deep Brain Stimulation?

Deep brain stimulation carries a genuine set of risks that range from the surgical procedure itself to long-term effects on speech, cognition, mood, and daily life with an implanted device. Most people considering DBS already know it works well for certain movement disorders and, increasingly, for psychiatric conditions. What gets less airtime are the trade-offs: bleeding during surgery, hardware that can break or become infected, changes in how you speak or walk, weight gain, restrictions on getting an MRI, and the unsettling possibility that your personality might shift in ways nobody predicted. None of these make DBS a bad treatment, but understanding them is what separates informed consent from hopeful guesswork.

Bleeding and Surgical Complications

Any surgery that involves threading electrodes deep into the brain carries a risk of bleeding. Intracranial hemorrhage is the most feared complication of DBS implantation, and while it is uncommon, it is not rare enough to ignore. One study tracking hemorrhage after DBS for Parkinson’s disease found 13 bleeding events among 11 patients, with male sex and high blood pressure emerging as the strongest risk factors.¹ A separate analysis of 357 lead implantations reported a roughly 3% overall risk of hematoma per lead, with about half of those causing symptoms and the other half found only on imaging.² The risk is not identical across brain targets. In that same series, stimulation aimed at the subthalamic nucleus (the most common Parkinson’s target) had a lower per-lead hemorrhage rate than stimulation aimed at the globus pallidus.

Hemorrhage can range from a small, clinically silent bleed that shows up on a post-operative scan to a larger bleed that causes weakness, confusion, or in rare cases permanent neurological damage. Most surgical teams mitigate this by stopping blood thinners well before surgery, carefully controlling blood pressure, and using imaging guidance to plan electrode paths that avoid blood vessels. Still, no technique eliminates the risk entirely. When DBS is used for obsessive-compulsive disorder, reported hemorrhage rates in some series have been as high as roughly 5 to 8 percent, though most large centers report lower numbers.³

Infection

Infection is the most common hardware-related complication of DBS, and it can happen at any point along the implanted system: around the electrodes in the skull, along the extension wire that runs under the skin of the neck, or at the pulse generator (the battery pack) implanted near the collarbone. A large single-center study found that about 6% of DBS procedures led to an infection over a decade, with most infections appearing within the first three months.⁴ Staphylococcus aureus, a common skin bacterium, was responsible for more than a third of these infections and tended to be more aggressive, often requiring hardware removal.

That last point matters. Treating a DBS infection frequently means taking the device out, clearing the infection with antibiotics, and then going through surgery again to reimplant everything once healing is confirmed. In the study above, hardware removal was necessary in about four out of five infections.⁴ Another center reported similar overall rates, with gram-positive bacteria dominating and roughly 4% of procedures developing an infection within 90 days.⁵ Infection risk also rises when the battery is replaced down the line, a point covered in more detail later.

Hardware Failures

DBS involves implanting a system with multiple physical components: thin leads with electrode contacts at the tips, extension cables connecting those leads to a pulse generator, and the generator itself. All of these can fail. A systematic review pooling data across multiple studies found a hardware-failure rate of about 7 per 100 individuals, with skin erosion and infection being the most common category.⁶

Lead fractures are a particularly frustrating problem. A decade-long case series from a national neurosurgical center found fractures in about 5% of patients, most often in the lead segment below the collarbone.⁷ Nearly all affected patients had a history of physical trauma or vigorous exercise. Two cases involved “Twiddler’s syndrome,” where the patient unconsciously rotates the pulse generator under the skin, twisting and eventually breaking the connected wires. When a lead fractures, stimulation abruptly stops or becomes erratic, and the only fix is surgical replacement.

People with dystonia appear to face higher hardware complication rates than those with other movement disorders. One early series found that all lead fractures and lead-migration events occurred in dystonia patients, at a rate of about 18% of that group, likely because dystonia involves powerful involuntary movements that can stress the implanted hardware over time.⁸

Speech, Gait, and Swallowing Problems

Among the side effects that affect daily quality of life, changes to speech are probably the most widely reported. A long-term retrospective study of patients who received subthalamic nucleus DBS for Parkinson’s disease found that roughly 17% developed speech impairment that was at least possibly related to DBS and either did not reverse or had unknown reversibility.⁹ Gait impairment followed a similar pattern, affecting about 12% of patients in the same study. These are not small numbers, and they represent effects that persisted over the long term, not temporary post-surgical swelling.

The encouraging part is that some speech and gait problems are stimulation-dependent, meaning they improve when settings are adjusted or stimulation is briefly turned off. One retrospective review of 29 patients showed that stimulation-induced gait and speech side effects could be identified within 30 minutes of turning off the device.¹⁰ This means clinicians have a quick way to test whether speech or walking troubles are caused by stimulation rather than by disease progression. However, adjusting settings to fix speech problems sometimes means accepting less tremor or rigidity control, creating an uncomfortable trade-off.

Swallowing safety is a related concern that gets less attention. Research comparing two common DBS targets found that patients who had subthalamic nucleus stimulation showed worsened swallowing safety scores after surgery, while those who had stimulation aimed at the globus pallidus did not.¹¹ Swallowing difficulty in a population that is already aging and dealing with a progressive neurological disease raises the risk of aspiration pneumonia, so this finding is clinically relevant even though it is seldom the first thing discussed in a pre-surgical consultation.

Cognitive Effects

DBS is generally considered cognitively safe in the broad sense: it does not cause dementia or dramatic intellectual decline. But it can chip away at specific cognitive abilities, most consistently verbal fluency. Verbal fluency is the ability to generate words quickly in response to a cue, like naming as many animals as you can in one minute. Multiple studies have found that subthalamic DBS leads to a measurable decline in this skill, especially in the semantic category (generating words within a category rather than starting with a particular letter).¹² That same study found that older age and longer disease duration predicted a steeper decline, suggesting that patients who wait until later in the disease course may be more vulnerable.

Beyond verbal fluency, declines in executive function and working memory have been reported, though less consistently.¹³ In practical terms, this can show up as difficulty multitasking, slowed problem-solving, or trouble holding information in mind while doing something else. For many patients, these changes are subtle enough that the motor benefits of DBS clearly outweigh them. But for someone whose work or daily routine depends heavily on quick verbal recall or mental flexibility, even a modest decline can be significant.

Psychiatric and Behavioral Risks

The psychiatric side of DBS risk gets complicated because the conditions DBS treats are themselves associated with depression, anxiety, apathy, and impulsivity. Teasing apart what the disease does from what the stimulation does from what medication changes do is genuinely difficult. That said, several patterns have been documented.

Suicidal ideation and suicide attempts following DBS have been reported across multiple studies, though the exact cause remains uncertain. Proposed explanations range from changes in the brain’s reward and impulse circuitry to the psychological difficulty of adjusting to a new self after surgery.¹⁴ The risk does not appear to be large in absolute terms, but it has been observed often enough that most DBS centers now include psychiatric screening and follow-up as part of the surgical program.

Impulse control disorders, such as compulsive gambling, hypersexuality, and binge eating, have a complex relationship with DBS. Some patients develop these behaviors after surgery, while others who already had them see improvement. A literature review identified multiple studies and case reports describing impulse control problems emerging after subthalamic DBS.¹⁵ The complicating factor is that DBS often allows patients to reduce their dopaminergic medications, which are themselves a major driver of impulse control problems in Parkinson’s disease. So the net effect depends heavily on how medications are managed after the device is turned on.

When DBS is used for OCD, hypomania is the most frequently reported stimulation-related behavioral side effect, though it typically resolves when settings are adjusted. Other stimulation-related effects in this population include insomnia, fatigue, and increased anxiety.³

Weight Gain

Weight gain after subthalamic DBS is common enough to be considered a recognized side effect, and the mechanism is not well understood. Some patients gain a substantial amount of weight in the year following surgery, and research has found that this is accompanied by significant increases in blood sugar levels.¹⁶ When combined with reduced physical activity, this metabolic shift can increase the long-term risk of developing insulin resistance or diabetes.

Interestingly, a recent study tried to determine whether the exact placement of the stimulating electrode within the subthalamic nucleus influenced weight change and found that it did not. This suggests the weight gain is not simply a matter of accidentally stimulating a nearby appetite center; something more systemic is going on, perhaps related to changes in energy expenditure, dopamine-driven reward circuits, or the reduced movement disorder symptoms themselves allowing patients to eat more comfortably.¹⁷

MRI Restrictions and Living with the Hardware

Once a DBS system is implanted, getting an MRI becomes a serious safety concern. The main risks include heating at the electrode tips (which could damage surrounding brain tissue), electrical currents induced by the MRI’s radiofrequency field, and potential malfunction of the pulse generator.¹⁸ Phantom studies have shown that the electrode tip heating risk is the most serious for modern devices.¹⁹

This does not mean MRI is absolutely prohibited. Newer DBS systems are labeled as MR-conditional, meaning they can be scanned under highly specific conditions: certain field strengths, certain coil types, specific absorption rate limits, and with the stimulator turned off or set to particular parameters. But many common clinical MRI protocols, including full-body scans and higher-field-strength machines, remain off-limits. For someone in their 50s or 60s who may eventually need MRI for joint problems, cancer screening, or stroke evaluation, this restriction can be a practical headache that persists for the rest of their life.

Beyond MRI, the pulse generator’s battery eventually runs out. Non-rechargeable generators typically last three to five years depending on stimulation settings, and each battery-replacement surgery carries its own complication risks. The infection rate after pulse generator replacement is more than three times higher than after the initial DBS surgery, possibly because scar tissue and repeated openings of the same surgical pocket create a more hospitable environment for bacteria.²⁰ Rechargeable generators reduce the frequency of replacement but require regular at-home charging sessions that some patients find burdensome.

What Happens When Stimulation Stops Suddenly

DBS is not a treatment you can simply walk away from. If stimulation stops abruptly, whether from a dead battery, a lead fracture, or a device malfunction, patients can deteriorate rapidly. In Parkinson’s disease, this can escalate to a condition sometimes called “DBS withdrawal syndrome,” which resembles neuroleptic malignant syndrome: high fever, severe rigidity, altered consciousness, and in extreme cases, death.

A case report and review of similar cases found that patients who develop this syndrome tend to have had Parkinson’s for many years and been on DBS for a long time, with averages around 19 years of disease and nearly 8 years of stimulation. These patients often did not respond to increased doses of oral dopaminergic medication; only restoration of DBS stimulation itself resolved the crisis.²¹ The implication is that the brain may become physiologically dependent on the stimulation over time, and the usual Parkinson’s medications cannot fully substitute for it during an emergency.

Loss of Benefit Over Time

For essential tremor, a common concern is that DBS seems to lose effectiveness over the years. Patients and clinicians have used the word “tolerance” to describe this, drawing an analogy to drug tolerance. A study analyzing long-term outcomes found evidence of DBS tolerance in hand function and activities of daily living, with higher stimulation frequencies and worse pre-operative scores predicting poorer long-term results.²²

However, the picture is muddier than it first appears. A separate investigation argued that tolerance may be over-reported and that much of the apparent loss of benefit is actually disease progression: the tremor gets worse over the years regardless of DBS, and the stimulation settings that once controlled it are no longer sufficient for the worsened tremor. That study recommended a careful work-up including checking electrode positions on imaging and evaluating off-stimulation tremor scores before concluding that tolerance is to blame.²³ Whether the cause is true tolerance or advancing disease, the result for the patient is the same: benefits that diminish over time, sometimes necessitating reprogramming, additional procedures, or acceptance of residual symptoms.

Personality and Relationship Changes

This is the risk category that clinical discussions tend to handle most awkwardly, because it does not fit neatly into a complication rate. Some DBS patients, and their partners, notice changes in personality after stimulation begins. A qualitative study of Parkinson’s patients and their families found that participants described both positive and negative personality shifts, with some attributing the changes to stimulation and others uncertain of the cause.²⁴ The study emphasized that these shifts need to be understood in context, since Parkinson’s disease itself and its medications also alter personality.

In people receiving DBS for treatment-resistant depression, a prospective qualitative study found that even when depression improved, the adjustment process created new friction. Patients became more assertive and independent, which sometimes led to conflict as caregivers had to give up roles they had occupied for years. New qualities like irritability and anger emerged in some patients, which were interpreted variously as reactions to the difficulties of re-entering social life, frustration at perceived lack of effect, or direct stimulation side effects at certain settings.²⁵ Patients also reported a persistent gap between who they wanted to be and who they felt they actually were after surgery. The device helped, but it did not deliver the complete transformation some had hoped for, and managing that disappointment is its own psychological challenge.

Adaptive DBS and Efforts to Reduce Side Effects

Standard DBS delivers continuous stimulation at fixed settings, regardless of what the brain is doing at any given moment. This one-size-fits-all approach is part of why side effects occur: settings that control tremor well during the worst moments may be excessive during calmer periods, and that excess stimulation is what produces speech difficulties, gait problems, or mood changes. Adaptive DBS, sometimes called closed-loop stimulation, aims to fix this by adjusting stimulation in real time based on brain signals.

A blinded randomized feasibility trial in four Parkinson’s patients found that adaptive DBS improved motor symptoms and quality of life compared to conventional continuous stimulation, while delivering less total energy to the brain.²⁶ Broader clinical evidence also supports the idea that adaptive stimulation could treat motor symptoms of both Parkinson’s and essential tremor with considerable energy savings.²⁷ Less total stimulation energy, delivered more precisely, should in theory reduce the side effects caused by overstimulation. The technology is still in early stages, with small trial sizes and limited long-term data, but it represents the most promising engineering response to many of the risks outlined above.

Considerations in Children

DBS is increasingly used in children with severe dystonia and other movement disorders that do not respond to medications. The evidence base in pediatric populations is much thinner than in adults, and most of what is known comes from small case series rather than large trials. A comprehensive review noted that adverse effects associated with DBS in pediatric populations are rare based on existing data but emphasized that further investigation is needed to define safety profiles accurately.²⁸ Children face additional considerations that adults do not: growing skulls that may shift electrode positions over time, the long duration of device dependence ahead of them (with multiple battery replacements), and the difficulty of detecting subtle cognitive or behavioral side effects in a developing brain. The higher rate of hardware complications in dystonia patients, already noted in adult studies, is also relevant here since dystonia is the most common pediatric indication for DBS.