Depression or Anxiety: These conditions are common in middle-aged women and can cause significant memory issues, even when CT scans appear normal. The symptoms can be subtle and may not be immediately recognized as related to mental health.

Sleep Disorders: Conditions like insomnia, sleep apnea, or restless leg syndrome can significantly impair memory and cognitive function. A normal CT scan does not rule out these diagnoses.
Hypothyroidism: This condition can cause memory problems, fatigue, and other cognitive issues. It's relatively common and can be diagnosed with blood tests.
Vitamin B12 Deficiency: A deficiency in vitamin B12 can lead to neurological symptoms, including memory loss. This is another condition that can be identified through blood tests.
Menopause or Perimenopause: Hormonal changes during this period can affect memory and cognitive function. Given the age of the patient, this could be a contributing factor.

Chronic Traumatic Encephalopathy (CTE): Although less common, if the patient has a history of head trauma (e.g., from sports or domestic violence), CTE could be a cause of memory issues. A normal CT scan does not rule out CTE.
Multiple Sclerosis: This autoimmune disease can cause a wide range of neurological symptoms, including memory problems. It's crucial to consider, especially if there are other neurological symptoms.
Brain Tumors (e.g., Meningioma): Some brain tumors may not be visible on a CT scan, especially if they are small or located in areas difficult to visualize. MRI would be a more sensitive test for these conditions.
Infections (e.g., Lyme Disease, Neurosyphilis): Certain infections can cause neurological symptoms, including memory issues. These would require specific tests for diagnosis.

Frontotemporal Dementia: A rare cause of dementia that can present with memory issues, among other symptoms. It's less likely given the patient's age but should be considered if other diagnoses are ruled out.
Mitochondrial Diseases: These are a group of disorders caused by dysfunctional mitochondria and can lead to a variety of neurological symptoms, including memory loss. They are rare and would require specific testing for diagnosis.
Creutzfeldt-Jakob Disease: A very rare, degenerative, and fatal brain disorder that can cause memory loss and other neurological symptoms. It's essential to consider, although it's extremely uncommon.