Reversible causes are thought to explain about eight percent of all dementias. Hypothyroidism is one of the most important causes of potentially reversible dementia. Deficits in memory, psychomotor slowing, general intelligence, and visuoperceptual skills are particularly involved and may not fully recover. We review a clinical case of a reversible dementia caused by hypothyroidism, in a patientfollowed in our institution.

Case report using clinical files, and brief literature review using Pubmed database, searching for the keywords “reversible dementia”, “hypothyroidism” and“psychosis”.

We present a case of a 76-year-old female patient admitted in our acute unitwith visual and auditive hallucinations and persecutory delusional ideation for 1 month. There was no previous psychiatric history. The patient was fully oriented in space, time and person, but there were clear memory deficits and sensitivity to antipsychotics. We used the Montreal Cognitive Assessment (MoCA) and the Frontal Assessment Battery (FAB), having the patient scored 17 on the former and 3 on the latter, failing in all tests except for grasping. On the blood tests, fT3 and fT4 levels werenear 0 and TSH was 40 µg/dL. We then discovered that the patient had a thyroidectomy 25 years ago and had been doing replacement treatment since then buthad discontinuated treatment on the previous six months. We also did magnetic resonance imaging that showed frontal microcirculatory changes but without clear atrophy. The patient was treated with aripiprazole 30mg and levothyroxine 0,150mg, being discharged after 1 month, without psychotic symptoms. About 1 year after, we repeated MoCa and FAB, scoring 27 and 16, respectively. The psychotic symptoms didn’t recur even after the antipsychotic discontinuation.

We present a case of hypothyroidism induced dementia with psychotic symptoms, that fully recovered with thyroid replacement treatment, without previous neurological or psychiatric history.