Higher-riskArticle link

Seizures in Lewy Body Dementia: Why They’re Missed and What You Can Do

Seizures are a real but often overlooked symptom in Lewy body dementia (LBD). Because they can look very different from the dramatic convulsions we picture, they’re frequently mistaken for other LBD symptoms like fluctuations in attention, fainting spells, or even just ‘off days.’ This article explains the types of seizures that can occur, why they’re so easy to miss, and gives you concrete steps to track, communicate, and get the right care for your loved one. You are not alone—there are practical things you can try today.

Key points

  • Seizures in Lewy body dementia are often non-convulsive (focal) and easily mistaken for dementia fluctuations, fainting, or just ‘off days.’
  • The most powerful diagnostic tool is a detailed spell log (date, time, what happened, duration, after-effects) and a video of the episode.
  • An ambulatory EEG (home brain wave monitor for 24-72 hours) is much more likely to catch seizures than a routine office EEG.
  • Common seizure triggers in LBD include sleep deprivation, infections (especially UTIs), dehydration, and certain medications.
  • Do not assume a spell is ‘just dementia’—push for a neurological evaluation if episodes are sudden, brief, and stereotyped.
  • Anti-seizure medications can be effective, but must be started at low doses and chosen carefully to avoid worsening LBD symptoms like Parkinsonism or confusion.

Why Seizures Are So Easy to Miss in Lewy Body Dementia

In Lewy body dementia, the brain is undergoing progressive damage due to abnormal clumps of a protein called alpha-synuclein. These clumps, called Lewy bodies, disrupt how brain cells communicate. While we often think of seizures as full-body convulsions, many seizures in LBD are ‘focal’ or ‘non-motor’—they may only cause a brief blank stare, a sudden confusion, or a strange sensation like a rising feeling in the stomach. Because LBD itself causes fluctuating cognition, hallucinations, and sudden drowsiness, a caregiver might easily write off a seizure as just another ‘bad spell’ of the dementia. Research suggests that a significant number of people with LBD have undiagnosed seizure activity, often only caught on an EEG (brain wave test) ordered for another reason. The key is that these episodes are sudden, brief, and often followed by a period of confusion or fatigue that is worse than their usual baseline.

What Seizure Types Can Occur in Lewy Body Dementia?

The most common seizure types in LBD are focal aware seizures (formerly called simple partial seizures) and focal impaired awareness seizures (complex partial seizures). In a focal aware seizure, your loved one might suddenly feel a wave of fear, a strange taste, or a visual disturbance (like seeing flashing lights) without losing consciousness. They may be able to tell you about it afterward. In a focal impaired awareness seizure, they might suddenly stop what they’re doing, stare blankly, and appear ‘absent’ for 30 seconds to two minutes. They may smack their lips, fidget with their clothes, or make random sounds. Afterward, they are often confused, sleepy, or irritable—this is called the postictal state. Generalized tonic-clonic seizures (the classic convulsive seizure) are less common in LBD but can occur, especially if the disease progresses or if there is an additional condition like vascular dementia (mixed dementia). Because LBD also causes ‘syncope’ (fainting) due to blood pressure drops, and ‘REM sleep behavior disorder’ (acting out dreams), seizures can be confused with these other LBD symptoms.

The Role of Mixed Dementia and Other Factors

Many people with LBD also have Alzheimer’s disease pathology or vascular damage in their brain—this is called mixed dementia. When mixed dementia is present, the risk of seizures may be higher because different types of brain damage can create multiple ‘irritation’ zones. Additionally, certain medications used in LBD, like cholinesterase inhibitors (e.g., donepezil, rivastigmine) or antipsychotics (sometimes prescribed for hallucinations), can lower the seizure threshold, making seizures more likely. Sleep deprivation, stress, infections (like a urinary tract infection), and electrolyte imbalances are also common triggers. Because LBD affects the autonomic nervous system (which controls heart rate, blood pressure, and sweating), a seizure might also trigger a dangerous drop in blood pressure or an irregular heart rhythm. This is why it’s critical to work with a neurologist who understands LBD and to never assume a ‘funny spell’ is just part of the dementia.

General caregiving information, not medical advice. Check medications and major care changes with your clinician.

Step-by-step

  1. Start a 'Spell Log' recording every unusual episode (blank stare, sudden confusion, fall, strange movement, odd smell or feeling). Include date, time, preceding event, exact behavior, duration (use phone timer), post-episode state, and possible triggers (poor sleep, infection, dehydration, stress).

  2. Record a video of the episode if safe. Capture the whole body and calmly narrate what you see (e.g., 'She stopped talking, eyes fixed left, right hand twitching'). If unsafe to record alone, ask another person to help.

  3. Schedule an appointment with a neurologist specializing in dementia or epilepsy. Bring the spell log and videos. Say: 'I am worried these episodes might be seizures because they are sudden, brief, and followed by confusion.' Request an ambulatory EEG (24–72 hour home monitor), as routine office EEGs are often normal.

  4. Review all current medications with the neurologist or pharmacist. Some drugs (e.g., bupropion, quetiapine, olanzapine, high-dose donepezil) lower the seizure threshold. Ask: 'Could any of these make seizures more likely, and is there a safer alternative?'

  5. Create a seizure safety plan: stay calm, time the seizure, never put anything in their mouth, clear sharp objects, pad their head if on floor, guide away from hazards. Call 911 if seizure lasts >5 minutes, breathing difficulty, or second seizure before regaining awareness. Afterward, place them in recovery position and stay until fully alert.

  6. If seizures are confirmed, discuss anti-seizure medication (e.g., levetiracetam, lamotrigine) with the neurologist. Ask about side effects, interactions with dementia meds, how to monitor effectiveness, and expect a low starting dose with slow increases.

What not to do

  • Do not assume every blank stare or confusion spell is dementia progression. LBD fluctuations wax/wane over hours/days; seizures are sudden, brief (seconds–2 minutes), and followed by distinct postictal sleepiness, confusion, or headache. If episodes are brief and stereotyped, push for seizure evaluation.

  • Do not restrain or hold your loved one during a seizure. Do not try to stop twitching movements. Gently guide them from hazards and let the seizure run its course while speaking calmly.

  • Do not offer food or drink during or immediately after a seizure—they may choke. Wait until fully alert and able to swallow safely, then offer a small sip of water.

  • Do not stop or change anti-seizure medication without explicit doctor instructions. Abrupt cessation can trigger status epilepticus. If side effects occur, call the neurologist—do not skip doses.

  • Do not overlook other causes of 'spells' (syncope from low blood pressure, TIA, cardiac arrhythmias). Additional testing (echocardiogram, tilt-table test) may be needed; your spell log helps differentiate these from seizures.

Practical tools

  • The 'Spell Log' Template

    A table with columns: Date/Time, Preceding Event, Observed Behavior (movements, sounds, awareness), Duration (use stopwatch), Post-Episode State (confused, tired, normal), Triggers (missed sleep, infection, dehydration, stress). Bring to every appointment.

  • Video Recording

    When an episode starts and is safe, record steadily, capture whole body, and narrate observations (e.g., 'Left arm jerking, not responding to name'). Ask for help if needed; never compromise safety for recording.

  • Ambulatory EEG

    A portable device worn at home for 24–72 hours recording brain activity during daily life. More likely to capture subtle LBD seizures than a routine office EEG. Requires a neurologist's prescription.

Discuss with your clinician

Ask your neurologist: ‘Could my loved one’s spells be focal seizures? Should we do an ambulatory EEG to find out?’

Ask: ‘Is it safe to start an anti-seizure medication like levetiracetam given their LBD and other medications? What are the specific side effects I should watch for?’

Ask: ‘Could any of their current medications (especially antidepressants or antipsychotics) be lowering their seizure threshold? Is there a safer alternative?’

If a seizure lasts more than 5 minutes, or if they have trouble breathing, or if they have multiple seizures without waking up, call 911 immediately. This is a medical emergency (status epilepticus).

Ask: ‘Should we see a cardiologist to rule out fainting (syncope) from blood pressure drops, which can look like seizures in LBD?’

Ask: ‘Are there any dietary changes (like a ketogenic diet) or supplements that might help reduce seizure frequency in LBD? I will not start anything without your approval.’

Related guides

Sources