Essential Tremor: This is the most common movement disorder and can present at any age, including young adulthood. It typically affects the hands, can be unilateral or bilateral, and is often exacerbated by stress, fatigue, or certain medications.

Parkinson's Disease: Although less common in young adults, Parkinson's disease can present with tremor, typically a resting tremor, and is often accompanied by other symptoms such as bradykinesia, rigidity, and postural instability.
Dystonic Tremor: This can occur in isolation or as part of a dystonia syndrome, where there are involuntary, patterned, and often repetitive muscle contractions.
Physiological Tremor: Enhanced physiological tremor can be seen in conditions of stress, anxiety, fatigue, or with certain substances like caffeine or medications.

Wilson's Disease: An inherited disorder of copper metabolism that can lead to neurological symptoms including tremor, ataxia, and dystonia, along with liver disease. It's crucial to diagnose early as treatment can prevent progression.
Multiple Sclerosis: Although tremor is not the most common presenting symptom, it can occur, especially intention tremor, and is associated with other neurological deficits.
Thyroid Dysfunction: Both hyperthyroidism and hypothyroidism can cause tremors, among other systemic symptoms.

Huntington's Disease: An autosomal dominant neurodegenerative disorder characterized by chorea, psychiatric symptoms, and cognitive decline. Tremor can be a part of the presentation, though it's less common.
Spinocerebellar Ataxias: A group of inherited disorders that affect the cerebellum and can present with ataxia, tremor, and other neurological symptoms.
Neurodegeneration with Brain Iron Accumulation (NBIA): A group of rare, inherited disorders characterized by progressive neurological deterioration, often with dystonia, parkinsonism, and other movement disorders.