Hypothyroidism Cognitive Decline — MRCPsych Paper B MCQ

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EasyOld Age PsychiatryHypothyroidism Cognitive DeclineMRCPsych Paper B

A 60-year-old woman presents with progressive cognitive decline, depression and constipation. She previously underwent thyroidectomy and has stopped taking her prescribed levothyroxine. Blood tests show a TSH concentration of 85 mU/L with undetectable free T4. Which reversible cause of cognitive decline is present?

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Correct answer: A — Hypothyroidism

The correct answer is A, hypothyroidism. Previous thyroidectomy, cessation of levothyroxine, a markedly raised TSH and undetectable free T4 establish severe overt primary hypothyroidism. Hypothyroidism can cause slowed thinking or memory impairment alongside depression and constipation, and is a potentially treatable cause considered during assessment of cognitive decline. Levothyroxine replacement would be expected to improve symptoms attributable to thyroid-hormone deficiency, although coexisting cognitive pathology should be reconsidered if impairment persists after euthyroidism is restored. Alzheimer's disease is not a reversible cause and does not explain the thyroid results. Normal pressure hydrocephalus would be suggested by gait impairment and urinary symptoms. No haematological, neurological or exposure findings suggest vitamin B12 deficiency or neurosyphilis.

Reference: NICE, Indicator IND118: Dementia—investigations for reversible or modifying causes, current indicator page. https://www.nice.org.uk/indicators/ind118-dementia-target-organ-damage-all-patients/chapter/indicator