Amnesia,Memory loss

Introduction

• Memory loss (amnesia) refers to the partial or complete inability to recall past events (retrograde) or form new memories (anterograde).

• It is a symptom, not a disease, but may arise from multiple causes — neurological, psychiatric, systemic, or drug-related.

• Some causes are reversible (e.g., vitamin B12 deficiency, hypothyroidism, depression), while others are progressive and irreversible (e.g., Alzheimer’s disease).

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Types of Memory Loss

1. Retrograde amnesia – loss of pre-existing memories.

2. Anterograde amnesia – inability to form new memories.

3. Transient global amnesia (TGA): sudden, temporary memory loss (resolves within 24 h).

4. Dissociative (psychogenic) amnesia: due to psychological trauma.

5. Progressive memory loss: dementia syndromes.

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Causes of Memory Loss

1. Neurological Causes

• Alzheimer’s disease (most common dementia).

• Vascular dementia (strokes, mini-strokes).

• Parkinson’s disease and Lewy body dementia.

• Frontotemporal dementia.

• Stroke or transient ischemic attack (TIA).

• Head trauma (concussion, TBI).

• Brain tumors.

• Infections: meningitis, encephalitis, HIV, syphilis.

• Epilepsy (temporal lobe seizures).

2. Nutritional / Metabolic

• Vitamin B1 (thiamine) deficiency → Wernicke-Korsakoff syndrome.

• Vitamin B12 deficiency.

• Hypothyroidism.

• Hypoglycemia.

• Chronic kidney or liver disease.

3. Psychiatric

• Depression (“pseudodementia”).

• Anxiety, PTSD.

• Dissociative disorders.

4. Substance-Related

• Alcohol intoxication / chronic alcoholism.

• Drug abuse (benzodiazepines, opioids, cannabis).

• Medications: sedatives, anticholinergics, some antihypertensives, chemotherapy.

5. Other Causes

• Aging-related mild cognitive impairment.

• Sleep disorders (apnea, insomnia).

• Toxic exposure (CO poisoning, heavy metals).

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Clinical Features

• Short-term memory loss: forgetting recent conversations, misplacing items.

• Long-term memory loss: forgetting personal history.

• Difficulty learning new information.

• Disorientation in time/place.

• Associated symptoms:

  • Language difficulty (aphasia).

  • Personality/behavioral changes.

  • Motor symptoms (Parkinsonism, weakness).

  • Seizures, headaches (neurological disease).

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Diagnostic Approach

1. History

• Onset: sudden (stroke, trauma) vs gradual (dementia).

• Progression: stable, improving, or worsening.

• Medications, alcohol, drug history.

• Family history of dementia.

• Psychosocial stressors.

2. Examination

• Neurological exam: cranial nerves, reflexes, gait, coordination.

• Mental state exam: orientation, mood, thought process.

• Cognitive screening: Mini-Mental State Exam (MMSE), MoCA.

3. Investigations

• Blood tests: CBC, electrolytes, thyroid function, B12, folate, LFT, RFT, glucose, HIV, syphilis.

• Brain imaging: MRI/CT for stroke, tumor, trauma, atrophy.

• EEG: seizures.

• Lumbar puncture: CNS infection.

• Neuropsychological testing: detailed memory and cognition assessment.

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Management and Treatment

Treatment depends on cause:

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A. General Measures

• Treat underlying cause whenever possible.

• Cognitive rehabilitation and memory training.

• Occupational therapy for daily functioning.

• Education and support for family/caregivers.

• Healthy lifestyle: regular exercise, balanced diet, adequate sleep, avoid alcohol.

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B. Pharmacological Treatment

1. Alzheimer’s Disease / Dementia

• Cholinesterase inhibitors:

  • Donepezil 5–10 mg orally at bedtime.

  • Rivastigmine 1.5–6 mg orally twice daily.

  • Galantamine 8–12 mg orally twice daily.

• NMDA receptor antagonist:

  • Memantine 5 mg orally once daily, titrate to 20 mg daily.

2. Vascular Dementia

• Control risk factors:

  • Aspirin 75–150 mg daily.

  • Atorvastatin 20–40 mg daily.

  • Antihypertensives: Enalapril 5–20 mg daily, Amlodipine 5–10 mg daily.

3. Wernicke-Korsakoff Syndrome

• Thiamine 100 mg IV/IM daily, followed by oral thiamine 100 mg daily.

• Abstain from alcohol.

4. Vitamin B12 Deficiency

• Hydroxocobalamin 1 mg IM every 2–3 months (maintenance).

5. Hypothyroidism

• Levothyroxine 50–100 mcg orally daily, titrate by TSH.

6. Depression-Related Memory Loss

• SSRIs: Sertraline 50–200 mg daily, Fluoxetine 20–40 mg daily.

7. Epilepsy-Related

• Sodium valproate 500–1000 mg/day orally in divided doses.

• Levetiracetam 500–1500 mg orally twice daily.

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C. Psychiatric / Behavioral Interventions

• Cognitive Behavioral Therapy (CBT) for depression/anxiety.

• Psychotherapy for trauma-related or dissociative amnesia.

• Support groups for patients and caregivers.

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D. Emergency Management

• Sudden memory loss + neurological deficits (stroke): urgent thrombolysis if within window.

• Hypoglycemia-induced amnesia: IV dextrose 50% bolus.

• Head trauma: stabilize, neuroimaging, neurosurgical care if needed.

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Complications

• Progressive dementia leading to dependence.

• Accidents, getting lost, unsafe driving.

• Depression, anxiety.

• Caregiver burden.

• Missed serious disease (tumor, stroke, infection).

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Prognosis

• Reversible causes (B12 deficiency, hypothyroidism, depression, alcohol): good prognosis with treatment.

• Progressive neurodegenerative diseases: gradual decline, supportive care.

• Stroke-related: depends on severity and rehabilitation.

• Transient global amnesia: usually complete recovery within 24 hours.

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Patient Education

• Not all memory loss means dementia — many causes are reversible.

• Keep a diary/calendar for reminders.

• Engage in mental exercises (reading, puzzles).

• Stay socially active and physically fit.

• Avoid excessive alcohol and sedatives.

• Seek medical care if memory loss is sudden, progressive, or associated with confusion, weakness, speech difficulty, or personality change.