The mother of a 6-year-old child expresses concern over the child's frequent temper outbursts. He deals with any frustration by bullying and hitting, and seldom shows any remorse for his actions. The nurse who gathers this data will note that the child's behaviours are most consistent with which DSM-5 diagnosis?

Choice A reason: Dementia is a clinical syndrome characterized by a chronic, global, and usually irreversible decline in cognitive function. It specifically targets higher-order cortical functions including memory, language (aphasia), purposeful movement (apraxia), and executive functioning. The progression is typically slow, spanning several years, which distinguishes it from acute confessional states.

Choice B reason: Depression in older adults (sometimes called pseudodementia) can mimic cognitive impairment. However, the onset of "forgetfulness" in depression is often more rapid, and the patient is typically distressed by their memory loss. In true dementia, the patient may be unaware of or indifferent to their cognitive deficits due to anosognosia.

Choice C reason: Medication toxicity usually presents as an acute change in mental status, often manifesting as delirium. While polypharmacy is a significant concern in geriatrics, the resulting cognitive impairment is typically reversible once the offending pharmacological agent is metabolized or discontinued, rather than being a "gradual and progressive" decline.

Choice D reason: Delirium is defined by its acute onset, fluctuating course, and disturbances in consciousness and attention. While it affects mental processing, it is a temporary physiological consequence of an underlying medical condition (like a urinary tract infection) rather than a permanent, progressive structural decline of brain tissue.

Choice A reason: Frequent induced vomiting, a common compensatory behavior in bulimia nervosa, leads to the excessive loss of gastric hydrochloric acid and potassium. This depletion results in metabolic alkalosis and hypokalemia, which is a critically low serum potassium level that can cause life-threatening cardiac dysrhythmias and muscle weakness.

Choice B reason: While tachycardia can occur secondary to dehydration or electrolyte imbalances, it is a non-specific sign and not the primary metabolic finding expected from chronic emesis. Hypokalemia is a more direct and clinically significant biochemical consequence of losing intracellular and extracellular fluids through the upper gastrointestinal tract.

Choice C reason: Hypercalcemia, or elevated serum calcium, is not a standard finding associated with chronic vomiting. In fact, repetitive emesis is more likely to cause shifts in other electrolytes like chloride and sodium. Calcium levels are generally maintained by parathyroid function unless there is significant renal impairment or specific supplement abuse.

Choice D reason: Hypolipidemia, or abnormally low lipid levels, is not a diagnostic expectation for a patient inducing vomiting. While nutritional deficiencies are common in eating disorders, the acute physiological risk and the hallmark laboratory finding specifically related to the act of purging is the disruption of serum electrolytes, particularly potassium.