Understanding the connection between tremors and dementia
Movement disorders, including tremors, are often not the first or most obvious symptom people think of when they hear the word 'dementia.' Yet, for certain neurodegenerative diseases, hand shaking is a significant part of the clinical picture. It is crucial for families and caregivers to recognize that while shaking hands is not a typical symptom of Alzheimer's disease, its presence does not rule out a dementia diagnosis. Instead, it points toward a more specific condition within the dementia spectrum that involves both cognitive and motor decline.
How are tremors classified?
To understand how they relate to dementia, it is helpful to know how doctors classify tremors. Tremors can be categorized primarily based on when they occur.
- Resting Tremor: This shaking happens when the body part is relaxed and not in use, such as when hands are resting in one's lap. The tremor lessens or disappears during voluntary movement. This is a classic symptom of Parkinson's disease, which is a key component of Dementia with Lewy Bodies.
- Action Tremor: This occurs during voluntary movement or when maintaining a posture against gravity. Action tremors are further broken down into postural (when holding a limb outstretched) and intention or kinetic (during a target-directed movement, like reaching for a cup). The most common type of action tremor is essential tremor.
- Task-Specific Tremor: This type of tremor only appears when performing certain activities, such as writing or playing an instrument.
Which types of dementia involve tremors?
Not all forms of dementia include tremors, but some do. Recognizing the specific type of dementia is essential for proper management and treatment planning.
- Dementia with Lewy Bodies (DLB): This is one of the most common causes of dementia and frequently involves motor symptoms that are very similar to those seen in Parkinson's disease. Symptoms include fluctuating cognition, visual hallucinations, and parkinsonism (tremors, stiffness, and slowed movement). Tremors can be an early sign, sometimes appearing before cognitive problems become prominent.
- Parkinson's Disease Dementia (PDD): PDD occurs when cognitive decline and dementia symptoms appear more than a year after the motor symptoms of Parkinson's disease (such as a resting tremor) have become established. Given that DLB and PDD share similar underlying pathology, they are often considered part of a spectrum known as Lewy Body Dementias.
- Vascular Dementia: In some cases, damage from strokes or small vessel disease can affect areas of the brain that control movement, potentially leading to tremors or gait problems.
Distinguishing between dementia-related tremors and other causes
It can be difficult to tell the difference between different types of tremors, especially in older adults, and requires a medical professional's evaluation. Here's a comparison to help understand the distinctions:
| Feature | Dementia with Lewy Bodies/PD | Essential Tremor (ET) | Other Causes |
|---|---|---|---|
| Cognitive Decline | A primary feature, often including hallucinations and fluctuating awareness. | Cognitive decline is not a primary feature, but some people with ET can experience mild cognitive issues. | Depends on the underlying cause (e.g., medication side effects, thyroid issues). |
| Tremor Timing | Typically a resting tremor (at rest, less prominent with movement). | Typically an action tremor (present during movement or posture). | Varies widely based on the cause. |
| Tremor Location | Often starts on one side of the body before becoming more widespread. | Usually affects both hands equally and can also affect the head and voice. | Can affect various parts of the body. |
| Associated Symptoms | Stiffness (rigidity), slow movement (bradykinesia), balance problems, and visual hallucinations. | Primarily the tremor itself, without other major motor symptoms. | Includes fatigue, anxiety, and other symptoms specific to the underlying issue. |
Beyond dementia: Other causes of hand tremors
It is important to remember that shaking hands is not always a sign of dementia. Other conditions can cause tremors, and some may coexist with dementia.
- Essential Tremor: This is the most common cause of tremors and is a distinct neurological condition that is not a form of dementia. It is characterized by an action tremor and tends to run in families.
- Medication Side Effects: Many medications can cause tremors, especially in older adults. These include certain antidepressants, anti-seizure drugs, and some asthma medications. In many cases, these tremors can be managed by adjusting the dosage or switching medication.
- Other Medical Conditions: Issues like an overactive thyroid, vitamin deficiencies (e.g., B12), and excessive caffeine intake can also cause or worsen tremors. Stroke or brain injuries can also lead to tremor.
- Anxiety and Stress: High levels of anxiety or stress can temporarily trigger or amplify physiological tremors.
What to do if you notice a tremor
If you or a loved one notices shaking hands or other involuntary movements, the first and most important step is to consult a healthcare provider. A doctor will conduct a thorough physical and neurological exam to help determine the cause. Keeping a detailed log of when the tremor occurs and any other symptoms can be very helpful for the diagnostic process.
Conclusion
While shaking hands is not a universal symptom of dementia, it is a key feature of specific forms like Dementia with Lewy Bodies and Parkinson's Disease Dementia. The nature of the tremor, whether it occurs at rest or during activity, and the presence of other symptoms can help differentiate it from other conditions like essential tremor. Accurate diagnosis is critical, not only for confirming the cause but also for developing an effective care plan. Caregivers should closely observe symptoms and seek professional medical advice to ensure the best possible care. For more information on managing dementia and finding support, the Alzheimer's Association is an excellent resource.
