A 62-year-old woman comes to the office due to difficulty remembering important dates and appointments. She also describes poor concentration, daytime sleepiness, and easy fatigability. She is concerned about her forgetfulness because her mother suffered from recurrent strokes and had severe memory loss. Her father died of chronic leukemia. Her daughter’s recent job loss has caused her a lot of stress. She does not use alcohol or tobacco. Her appetite is decreased but she has gained 2 kg (4.4 lbs) over the last 3 months. She recently visited an otolaryngologist for hoarseness. She takes occasional aspirin for joint pain and has been taking over-the-counter laxatives for constipation. She denies any other medication use. Which of the following is the most likely diagnosis in this patient?
Although this patient comes in due to memory problems, several features of her presentation suggest she most likely has hypothyroidism. In addition to memory changes, she has several manifestations of hypothyroidism, including:
Confirming hypothyroidism as an etiology of her presentation is important because administration of levothyroxine will quickly reverse her symptoms. Hypothyroidism presenting as memory problems can sometimes be difficult to distinguish from pseudodementia, a presentation of major depression in the elderly. Although this patient has several features of depression (eg, poor concentration, decreased energy, sleep disturbances, weight gain), she does not clearly have depressed mood or anhedonia; furthermore, depression would not explain her hoarseness and constipation (Choice H).
(Choices A and B) Alzheimer disease presents with early problems in visuospatial abilities (eg, getting lost in their neighborhood) and anterograde memory formation. Old memories tend to be preserved. Personality and behavioral changes (eg, hypersexuality, agitation) may occur as the disease progresses. Hallucinations and changes in alertness are late findings. Unlike Alzheimer disease, dementia with Lewy bodies presents with alterations in alertness, visual hallucinations, and extrapyramidal symptoms. Memory deficits occur later in the course of disease than in Alzheimer disease.
(Choice C) Multiinfarct dementia classically causes a stepwise deterioration as damage from multiple strokes slowly adds up. It is characterized by risk factors for vascular disease, history of cerebrovascular disease, and imaging evidence of strokes. Psychiatric disturbances such as depression and agitation are common.
(Choice E) Normal pressure hydrocephalus is characterized by dementia, abnormal gait, and urinary incontinence. The gait is broad-based and shuffling and patients tend to be bradykinetic.
(Choice F) Huntington disease is an autosomal dominant neurodegenerative disease affecting the caudate and putamen. The mean age of onset is between age 35-44. Symptoms include choreathetoid movements, behavioral disturbances, and dementia.
(Choice G) Chronic subdural hematomas are more common in elderly patients and those with alcohol use disorder due to their decreased brain volume and propensity for falls. They present insidiously with headache, decreased consciousness, cognitive and memory deficits, balance problems, aphasia, or motor deficits. This patient does not have headache or other symptoms most consistent with chronic subdural hematomas.
(Choice I) Vitamin B12 deficiency typically presents as dementia with megaloblastic anemia and posterior spinal column deficits. The most common cause is pernicious anemia.
(Choice J) Thiamine deficiency can lead to Wernicke-Korsakoff syndrome, which presents as ataxia, ophthalmoplegia, and confusion (Wernicke) in addition to confabulation and amnesia (Korsakoff). It is particularly common in patients with alcohol use disorder.
(Choice K) Aspirin and laxatives are not classically associated with dementia and would not explain the patient's other features (eg, constipation, hoarseness).
Educational objective:
Hypothyroidism is an important cause of reversible changes in memory and mentation. It will be accompanied by systemic changes such as weight gain, fatigue, and constipation.