The patient's acute onset of psychotic symptoms (hallucinations, disorganized speech) lasting for 2 weeks in the context of a significant psychosocial stressor is characteristic of brief psychotic disorder. By definition, the symptoms last from one day to one month, with an eventual full return to premorbid functioning.

• Schizophrenia and schizophreniform disorder are incorrect due to the short duration of symptoms (less than 6 months and 1 month, respectively).
• Acute stress disorder involves intrusive symptoms, avoidance, and hyperarousal following a traumatic event, but does not typically include prominent psychotic symptoms like hallucinations and disorganized speech.

This patient's presentation is classic for delusional disorder. The key features are one or more non-bizarre delusions (in this case, jealous type) that persist for at least one month, without the other psychotic symptoms seen in schizophrenia (e.g., hallucinations, disorganized speech). Crucially, functioning outside the impact of the delusion is not markedly impaired.

• Schizophrenia is incorrect because the patient lacks other Criterion A symptoms and his overall functioning is not significantly impaired.
• Paranoid personality disorder involves a pervasive distrust and suspiciousness of others, but not a fixed, false belief of this magnitude.
• Schizoaffective disorder is incorrect as there are no mood episodes or other psychotic symptoms.

Schizoaffective disorder is diagnosed when a patient meets the criteria for a major mood episode (depressive or manic) that occurs concurrently with the active-phase symptoms of schizophrenia. The key diagnostic feature is the presence of delusions or hallucinations for at least 2 weeks in the absence of a major mood episode during the lifetime duration of the illness. This patient has persistent psychosis with a superimposed major depressive episode, fitting the criteria for schizoaffective disorder.

• Major depressive disorder with psychotic features is incorrect because the psychosis persists even when the mood episode resolves.
• Bipolar I disorder with psychotic features is incorrect for the same reason, and there is no evidence of a manic episode.
• Schizophrenia is incorrect because the mood symptoms are prominent and meet the criteria for a full major depressive episode.

This clinical picture is classic for methamphetamine-induced psychosis. Key features include paranoia, agitation, sympathetic hyperactivity (tachycardia, hypertension, mydriasis, diaphoresis), and tactile hallucinations (formication, or the sensation of bugs crawling on the skin). The skin excoriations from picking at these perceived bugs and the poor dental hygiene ('meth mouth') are also highly suggestive.

• Alcohol intoxication typically causes sedation, while withdrawal can cause hallucinations, but the overall picture is less consistent.
• Heroin (an opioid) causes miosis (constricted pupils) and CNS depression.
• Cannabis can induce psychosis, but it is less likely to cause such profound sympathetic stimulation and formication.

For any patient presenting with a first episode of psychosis, it is crucial to rule out medical and substance-induced causes. A standard initial workup includes a complete physical and neurologic exam, basic laboratory tests (e.g., CBC, electrolytes, BUN, creatinine, LFTs, TSH), and a urine toxicology screen to rule out substance-induced psychotic disorder. This ensures that a treatable underlying condition is not missed before diagnosing a primary psychotic disorder.

• An EEG or lumbar puncture would be indicated if there were specific signs suggesting a seizure disorder or CNS infection, which are not present here.
• Genetic testing is not part of the routine clinical workup for schizophrenia.

For patients with schizophrenia who have a history of nonadherence to oral medication, long-acting injectable (LAI) antipsychotics are the most effective strategy for improving adherence and reducing relapse rates. An LAI, such as paliperidone palmitate or aripiprazole lauroxil, is administered every few weeks to months, bypassing the need for daily oral dosing.

• Switching to oral clozapine is indicated for treatment-resistant schizophrenia, not nonadherence.
• Adding a benzodiazepine does not address the core issue of antipsychotic nonadherence.
• Group therapy can be a useful adjunct, but it is less effective than an LAI for solving the specific problem of medication nonadherence.

While antipsychotic medications are effective for the positive symptoms of schizophrenia, they have limited efficacy for negative symptoms (avolition, anhedonia, flat affect, etc.). Evidence-based psychosocial interventions, such as social skills training, supported employment, and cognitive-behavioral therapy for psychosis, are the most effective treatments for improving functional outcomes and addressing persistent negative symptoms.

• Increasing the risperidone dose is unlikely to help with negative symptoms and may worsen them or cause side effects.
• Adding benztropine would only be indicated for extrapyramidal symptoms, not primary negative symptoms.
• Switching to a first-generation antipsychotic is generally associated with worse negative symptoms compared to second-generation agents.

The patient is experiencing an acute dystonic reaction, a type of extrapyramidal side effect (EPS) common with high-potency first-generation antipsychotics like haloperidol. The symptoms include oculogyric crisis (upward eye deviation) and torticollis (neck twisting). The treatment of choice is an intramuscular injection of an anticholinergic agent like benztropine or an antihistamine with anticholinergic properties like diphenhydramine, which provides rapid relief.

• Lorazepam can help with associated anxiety but is not the primary treatment.
• Propranolol is used to treat akathisia, another form of EPS.
• Discontinuing haloperidol is a long-term consideration, but the acute, painful reaction requires immediate pharmacologic intervention.

The patient is exhibiting signs of drug-induced parkinsonism, a common extrapyramidal side effect of antipsychotics with potent D2 receptor blockade, like risperidone. The symptoms include bradykinesia, rigidity, and tremor. The most appropriate management options are to lower the dose of the antipsychotic, switch to an agent with a lower risk of EPS (e.g., quetiapine), or add an anticholinergic medication like benztropine or amantadine. Adding benztropine is a common and effective initial strategy.

• Levodopa/carbidopa is used for Parkinson's disease and can worsen psychosis.
• Increasing the risperidone dose would worsen the parkinsonian symptoms.
• A brain MRI is not indicated as the clinical picture is highly suggestive of a medication side effect, not a new neurologic event.

This patient is presenting with classic signs of tardive dyskinesia (TD), a potentially irreversible movement disorder caused by long-term exposure to dopamine-blocking agents. Management involves discontinuing the offending agent if possible and switching to an antipsychotic with lower TD risk (like clozapine). If symptoms persist or the antipsychotic cannot be stopped, the treatment of choice is a vesicular monoamine transporter 2 (VMAT2) inhibitor, such as valbenazine or deutetrabenazine.

• Increasing the antipsychotic dose can temporarily mask TD but ultimately worsens the underlying pathology.
• Adding benztropine or other anticholinergics can worsen TD.
• Reassurance is inappropriate as TD can be disfiguring, distressing, and is not always self-limiting.