MD Study Guide 2026

Borderline personality disorder is characterized by unstable identity, intense fear of abandonment, chronic emptiness, and impulsive self-destructive behaviors including self-harm.

Psoriasis is characterized by well-demarcated erythematous plaques covered with silvery-white scales caused by accelerated keratinocyte turnover.

Tardive dyskinesia is a late-onset movement disorder associated with prolonged antipsychotic use, characterized by involuntary, repetitive orofacial and limb movements that persist beyond medication cessation.

DSM-5 requires that PTSD symptoms (intrusion, avoidance, negative cognitions/mood, and hyperarousal) persist for more than 1 month following traumatic exposure, distinguishing it from acute stress disorder.

Continuous Positive Airway Pressure (CPAP) therapy is the gold standard and most effective first-line treatment for moderate to severe obstructive sleep apnea. It works by providing a continuous stream of air to keep the airway open during sleep. While mandibular advancement devices, surgery, and lifestyle modifications like weight loss are also treatment options, they are typically considered for mild to moderate OSA or for patients who cannot tolerate CPAP.

Angiotensin-Converting Enzyme (ACE) inhibitors work by blocking the enzyme that converts angiotensin I to angiotensin II. This reduces levels of angiotensin II, a potent vasoconstrictor, leading to vasodilation and lower blood pressure. Additionally, ACE is responsible for breaking down bradykinin, a vasodilator. By inhibiting ACE, these drugs increase bradykinin levels, which further contributes to vasodilation and the overall antihypertensive effect.