Depression with Cognitive Impairment: Differentiating Pseudodementia from Dementia
Mrs. L is a 78-year-old woman brought by her son because of progressive memory problems over 6 months. She reports feeling sad, has lost interest in activities, and has poor appetite with 10-lb weight loss. She often says 'I don't know' to questions and gives up easily on cognitive tasks. Her MMSE is 22/30, with deficits in recall and attention. She scores 18 on the Geriatric Depression Scale (GDS). She has a history of hypertension and hypothyroidism, well controlled. Labs including TSH, B12, and CBC are normal. She lives alone and has become more withdrawn. The son wonders if she has Alzheimer's disease.
1. How would you differentiate between major depression with cognitive impairment (pseudodementia) and dementia with comorbid depression?
Read the worked answer
Differentiating pseudodementia from dementia can be challenging. Key features favoring pseudodementia: acute or subacute onset, prominent mood symptoms, complaints of memory loss with emphasis on disability, 'don't know' answers, variability in performance, and improvement with encouragement. In contrast, dementia typically has insidious onset, patients may minimize deficits, and they often confabulate or make near-miss answers. Neuropsychological testing can help: in depression, performance is often impaired but improves with cues, and there is a pattern of reduced effort. In dementia, encoding and storage deficits are prominent. Also, depression can be a prodrome of dementia. In this case, the patient has significant depressive symptoms and cognitive complaints. It is reasonable to treat depression first and reassess cognition after remission. If cognitive impairment persists, further evaluation for dementia is warranted.
2. What is your treatment plan for this patient? Include medication choice and monitoring.
Read the worked answer
Initiate treatment for major depression. Given her age and comorbidities, an SSRI is first-line. Sertraline or escitalopram are good choices due to favorable side effect profiles. Start at a low dose (e.g., sertraline 25 mg daily) and titrate slowly. Avoid paroxetine due to anticholinergic effects. Monitor for hyponatremia (check sodium in 2-4 weeks), GI side effects, and falls. Also, screen for suicidal ideation. Psychotherapy, such as cognitive-behavioral therapy or problem-solving therapy, can be effective. Reassess cognitive function after 8-12 weeks of treatment. If cognition improves, pseudodementia is likely. If not, refer for neuropsychological testing and consider neuroimaging. Also, address social isolation: encourage activities and caregiver support. Educate the son about the possibility of dementia and the need for follow-up.