Differential Diagnosis for a 60-year-old Female with Complex Psychiatric Symptoms

Single Most Likely Diagnosis

• Bipolar Disorder with Psychotic Features: This diagnosis is considered the most likely due to the combination of depressed mood, anxiety, obsessive thoughts, impulsive behavior, hyperactive behavior, homicidal thoughts, and auditory hallucinations. The presence of both depressive and manic symptoms (such as hyperactive behavior) along with psychotic symptoms (auditory hallucinations) strongly suggests a bipolar disorder.

Other Likely Diagnoses

• Schizoaffective Disorder: This condition is characterized by a combination of schizophrenia symptoms (like hallucinations) and mood disorder symptoms (depression or mania), which could fit the patient's presentation. The long duration of symptoms (3 years) and the mix of mood and psychotic symptoms make this a plausible diagnosis.
• Major Depressive Disorder with Psychotic Features: Although the patient exhibits manic symptoms, the primary complaint of depressed mood and the presence of psychotic symptoms could also suggest a severe depressive disorder with psychotic features, especially if the manic symptoms are less prominent or intermittent.
• Anxiety Disorder with Obsessive-Compulsive Symptoms: The presence of anxiety and obsessive thoughts could indicate an anxiety disorder, but the presence of other symptoms like hallucinations and homicidal thoughts makes this less likely as a standalone diagnosis.

Do Not Miss Diagnoses

• Neurocognitive Disorder (e.g., Dementia): In elderly patients, it's crucial not to miss a neurocognitive disorder, which can present with mood changes, psychosis, and behavioral disturbances. Dementia can sometimes manifest with psychiatric symptoms that mimic other disorders.
• Delirium: Although less likely given the chronic nature of the symptoms, delirium can present with a wide range of psychiatric symptoms, including hallucinations and fluctuating mood. It's a medical emergency that requires immediate attention.
• Substance-Induced Psychotic Disorder: Substance use or withdrawal can cause a wide range of psychiatric symptoms, including psychosis and mood disturbances. It's essential to rule out substance use as a cause of the patient's symptoms.

Rare Diagnoses

• Wilson's Disease: A rare genetic disorder that can cause psychiatric symptoms, including mood changes, psychosis, and obsessive-compulsive symptoms, along with neurological symptoms. It's rare but important to consider in younger patients or those with a family history.
• Huntington's Disease: Another genetic disorder that can cause psychiatric symptoms, including depression, anxiety, and psychosis, along with characteristic motor symptoms. It's less likely in a new presentation at 60 without prior symptoms but should be considered if there's a family history.

Medication to Start the Patient On

Given the complexity of the patient's symptoms, a comprehensive treatment plan would likely involve a combination of medications. For a patient with suspected bipolar disorder or schizoaffective disorder, initial treatment might include:

• Mood Stabilizer (e.g., Lithium, Valproate): To address mood symptoms.
• Atypical Antipsychotic (e.g., Olanzapine, Risperidone): For psychotic symptoms and mood stabilization.
• Selective Serotonin Reuptake Inhibitor (SSRI) or Serotonin-Norepinephrine Reuptake Inhibitor (SNRI): For depressive and anxiety symptoms, but with caution and ideally after the patient is stabilized on a mood stabilizer or antipsychotic to avoid inducing mania.

It's crucial to tailor the treatment to the patient's specific symptoms and response, under the guidance of a psychiatric professional.