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A 58-year-old woman developed severe progressive dementia. Markedly impaired memory, apraxia and abnormal behaviour with psychotic components suggested Alzheimer's syndrome. But there were atypical signs, namely abnormal coordination, occasional tremors and dysarthria. A search for a possible toxic cause was at first unsuccessful, but by chance a "gastric power" containing 0.1 g of bismuth gallate per gram of powder, was found in her night-table. The patient had taken it regularly over years, at a dosage of up to 1.5 g daily, to combat gastric acidity. Six days after stopping the drug the blood bismuth level was 70 micrograms/l, which within 1-2 months fell to 9 micrograms/l. After 4 1/2 months in hospital the patient was discharged in a good general condition and with normal intellectual function.

Typical clinical signs and symptoms of bismuth intoxication are illustrated in a cases of a 45-year-old woman. Initially psychasthenia appears followed by acute delirium with ataxia, myoclonic jerks and occasionally coma. If patients survive the acute phase they recover only gradually following discontinuation of bismuth medication. In cases of extreme intoxication, permanent memory deficits may occur. Etiology, pathogenesis, laboratory findings, differential diagnosis and therapy of this rare iatrogenic encephalopathy are discussed.

The central metabolism of dopamine, serotonin, cyclic AMP and cyclic GMP was studied by use of the probenecid test in three patients with bismuth encephalopathy and in one patient with mercury encephalopathy. The accumulation of HVA and of cGMP in the cerebrospinal fluid was depressed during the acute phase of bismuth encephalopathy with severe hyposomnia, while it was increased in a patient with regression of clinical symptoms and normal in a patient with more advanced recovery. The patient with chronic mercury poisoning showing a severe cerebellar ataxia and rigidity had an almost complete suppression of HVA accumulation and an increase of cGMP accumulation. No pronounced differences of 5-HIAA and cAMP behavior were found. It is concluded that the central metabolism of dopamine and of cGMP is severely affected in bismuth and mercury encephalopathies.