Frequent shoulder shrugging may be caused by the following conditions: First, it may be a problem of personal habits. Second, it may be caused by nerve cells in the brain or tumors that compress the brain tissue, resulting in abnormal discharge of brain cells and involuntary twitching of the shoulder and neck muscles, resulting in frequent shrugging of the shoulders. Third, it may be caused by muscle strain in the neck or cervical spondylosis. Muscle strain in the neck causes discomfort in the shoulder and often requires shrugging to relieve muscle spasm and discomfort, which leads to this symptom. If it is cervical spondylosis, it may compress the nerve roots in the shoulder and stimulate the shoulder muscles to develop neurological abnormalities in sensation, which may also cause this symptom.