Cognitive dysfunction associated with elemental mercury ingestion and inhalation: a case study.

A 63-year-old man with a history of alcohol dependence ingested elemental mercury as a suicide gesture. Serial abdominal X-rays showed gradual but incomplete clearance of mercury from the colon. Routine chest X-ray showed evidence of punctate radiopaque materials in the lower lobe of the right lung. Blood and urine mercury levels both exceeded thresholds considered to be associated with cognitive dysfunction. Elicited cognitive deficits were most prominent in processing speed, flexibility, and response inhibition. Semantic fluency, visuospatial processing, and recall memory for visual and low-context verbal material were also affected. The deficits may have been attributable primarily to alcohol abuse. Elemental mercury is not readily absorbed from the gastrointestinal tract; however, mercury vapor, which was inhaled inadvertently, readily crosses the blood-brain barrier and is neurotoxic. We argue, therefore, that mercury toxicity is more likely than not to have been a factor contributing to the patient's cognitive dysfunction.

Depression with versus without manic features in rapid-cycling bipolar disorder.

Depression has been identified as a hallmark feature of rapid-cycling bipolar disorder, although less attention has been paid to the presence of manic features accompanying depression in rapid cyclers. To provide greater information about the extent to which depression arises with or without salient manic features in rapid cycling, we conducted a preliminary study of rapid cycling in outpatients seeking treatment at an academic specialty center for bipolar disorder. Forty DSM-IV affectively symptomatic bipolar outpatients with past year DSM-IV rapid cycling underwent systematic evaluation of symptoms and illness characteristics. Manic and depressive symptoms, treatments, and clinical features were rated by standardized scales. Major depression was present in most rapid cyclers (85%), but salient manic features were also evident in half of all depressed rapid cyclers. A lifetime history of suicide attempts was significantly more common in rapid cyclers who presented with major depression plus salient manic features than in those who presented with pure depression or pure mania (p = .033). Antidepressants were being prescribed for approximately one third of depressed rapid cycling patients regardless of the presence of concomitant manic features, whereas mood stabilizers tended to be used less often when manic features accompanied depression. Depression in conjunction with manic symptoms, rather than pure depression alone, may be more common among rapid-cycling bipolar patients who seek treatment. Lifetime suicide risk may be greater among rapid cycling patients whose depression occurs in tandem with manic symptoms. Prescribing habits in the community that favor antidepressants over mood stabilizers may promote further mood destabilization in this population. Further studies with larger sample sizes are needed to affirm these provisional findings.