Essential tremor (ET) is a neurological condition causing involuntary, rhythmic shaking. While known for its motor symptoms, growing evidence suggests ET is not purely a movement disorder. Research has uncovered a connection between the condition and subtle changes in cognitive abilities, prompting a deeper look into how ET affects the brain beyond physical tremors.
The Cognitive Side of Essential Tremor
Not every person with ET will experience cognitive changes, but a pattern of subtle difficulties has been identified. These are not severe memory lapses but are more nuanced issues related to executive functions—the mental skills for planning, organizing, and managing time. An individual might find it harder to multitask or switch between activities smoothly.
Other changes involve verbal abilities, such as difficulties with verbal fluency—the ease of finding the right words during conversation. This is not an issue with language comprehension but a slight delay in retrieving specific words. There can also be mild challenges with learning and recalling new verbal information. These cognitive symptoms are mild and their presence suggests ET’s impact extends beyond motor control.
Studies show that individuals with ET, particularly those with a later age of onset, have a higher likelihood of developing mild cognitive impairment (MCI). Research indicates the prevalence of MCI in people with ET is approximately double that of the general population. The rate of conversion from normal cognition to MCI is also elevated for those with the condition.
Uncovering the Neurological Connection
The link between ET’s motor and cognitive symptoms originates in the cerebellum. For years, this brain region was understood to only coordinate movement, posture, and balance. Neuroscience has since revealed the cerebellum’s broader responsibilities, including involvement in higher-order mental processes.
Neuroimaging studies show the cerebellum is active during tasks related to language, working memory, and planning. It communicates with the cerebral cortex through extensive neural circuits. The same disruptions within these circuits that cause tremors are likely responsible for the associated cognitive difficulties.
The tremor and cognitive symptoms are two outcomes of the same underlying neurological issue. The cerebellar pathways that fine-tune motor activity are intertwined with those that modulate thought processes. When these circuits are affected in ET, the disruption can manifest as both physical shaking and subtle cognitive impairments.
Distinguishing from Other Neurological Conditions
A concern for those with ET is whether cognitive changes signal another condition, like Alzheimer’s or Parkinson’s disease. While there is overlap, the cognitive profiles are distinct. The memory problems in Alzheimer’s are more severe, affecting short-term memory and the ability to learn new information, which is less characteristic of ET.
The distinction from Parkinson’s disease involves motor and non-motor symptoms. ET is characterized by an action tremor (occurring during voluntary muscle use), whereas Parkinson’s involves a resting tremor. Cognitively, while both can affect executive functions, Parkinson’s is more associated with visuospatial difficulties. The rate of progression to dementia in ET, while elevated, stems from different underlying pathology than Parkinson’s.
Diagnostic misclassification can be a challenge, as kinetic tremor can be an early sign of Parkinson’s. However, specific tools and a clinical assessment help differentiate the conditions. For instance, a DaTscan measures dopamine uptake in the brain and can distinguish ET from parkinsonian syndromes, as dopamine levels are normal in ET. An accurate diagnosis is necessary for understanding the prognosis and management approach.
Managing Symptoms and Seeking Evaluation
Anyone with ET who notices changes in memory or thinking should consult a neurologist. A physician may recommend a formal evaluation to understand the nature and extent of any cognitive changes.
This evaluation involves neuropsychological testing, using standardized tests to assess memory, attention, and executive skills. Testing establishes a baseline and helps determine if the difficulties align with ET’s known cognitive profile or suggest another issue. Motor-free tests are often used to get an accurate assessment without interference from the tremor.
There are no specific treatments to reverse the cognitive symptoms of ET, but strategies can help manage them. Regular physical exercise, a balanced diet, and mentally stimulating activities like puzzles or social events are beneficial. These lifestyle measures support cognitive function and help individuals cope with the mild challenges of ET. A medical evaluation remains the best course for an accurate diagnosis and a personalized plan.