Differential Diagnosis

The patient's presentation of personality changes, inappropriate social behavior, and apathy with relatively intact memory suggests a neurological or psychiatric condition. Here's a categorized differential diagnosis:

• Single most likely diagnosis

  • Frontotemporal dementia (FTD): This condition is characterized by changes in personality, social behavior, and emotional regulation, often with apathy, and can present with relatively preserved memory, especially in the early stages.

• Other Likely diagnoses

  • Alzheimer's disease with prominent frontal lobe involvement: While memory loss is a hallmark of Alzheimer's, some patients may exhibit significant frontal lobe symptoms early in the disease, including personality changes and inappropriate behavior.
  • Vascular dementia: Depending on the areas of the brain affected by vascular disease, patients can exhibit a range of cognitive and behavioral symptoms, including personality changes and apathy.
  • Traumatic brain injury (TBI): A history of TBI, especially if it involved the frontal lobes, could lead to similar symptoms, including changes in personality and social behavior.
  • Huntington's disease: This genetic disorder can cause cognitive decline, psychiatric symptoms, and significant changes in personality and behavior, often with chorea.

• Do Not Miss diagnoses

  • Brain tumor: A tumor in the frontal lobe could cause the described symptoms, and missing this diagnosis could be fatal. Regular neurological exams and imaging studies are crucial.
  • Normal pressure hydrocephalus (NPH): Although more commonly associated with gait disturbance, dementia, and urinary incontinence, NPH can sometimes present with behavioral changes and apathy.
  • Chronic subdural hematoma: Especially in the elderly, even minor head trauma can lead to a chronic subdural hematoma, which can cause a variety of neurological symptoms, including personality changes.
  • Neurosyphilis: This condition can cause a wide range of neurological symptoms, including personality changes, and is important to diagnose due to its treatability with antibiotics.

• Rare diagnoses

  • Creutzfeldt-Jakob disease: A rare, degenerative, fatal brain disorder that can cause dementia, personality changes, and other neurological symptoms, though it typically progresses much more rapidly than the conditions listed above.
  • Wilson's disease: A genetic disorder that leads to copper accumulation in the brain and liver, which can cause neurological symptoms, including personality changes and psychiatric symptoms, though it is more commonly diagnosed in younger individuals.
  • Hashimoto's encephalopathy: A rare condition associated with Hashimoto's thyroiditis, characterized by cognitive decline, seizures, and psychiatric symptoms, which can sometimes present with personality changes and apathy.