Differential Diagnosis for the Presented Case

The patient's symptoms of decreased need for sleep, increased goal-directed activity, rapid and pressured speech, and impaired work performance due to excessive involvement in work projects suggest a bipolar disorder. Here's the differential diagnosis categorized for clarity:

• Single Most Likely Diagnosis

  • Hypomania: This condition is characterized by a distinct period of abnormally and persistently elevated, expansive, or irritable mood and lasting at least 4 consecutive days. The symptoms include inflated self-esteem or grandiosity, decreased need for sleep, more talkative than usual or pressure to keep talking, flight of ideas, distractibility, increase in goal-directed activity, and excessive involvement in activities that have a high potential for painful consequences. The patient's presentation of sleeping only 4 hours per night, increased goal-directed activity, rapid and pressured speech, and starting several new projects with grand plans aligns closely with hypomania, especially since his work performance has been impaired but he can still carry out daily activities.

• Other Likely Diagnoses

  • Mania: While mania shares many symptoms with hypomania, such as elevated mood, increased activity, and reduced need for sleep, it is distinguished by its severity and the presence of psychotic symptoms or the need for hospitalization to prevent harm to self or others. The patient's symptoms, although significant, do not seem to have reached the severity required for a diagnosis of mania, as there's no mention of psychotic symptoms or severe impairment in social or occupational functioning that necessitates hospitalization.
  • Mixed Episode: A mixed episode involves symptoms of both mania/hypomania and depression occurring nearly every day for at least 1 week. While the patient shows clear signs of hypomania, there's no indication of depressive symptoms such as sadness, loss of interest, or significant weight loss/gain, making this diagnosis less likely.

• Do Not Miss Diagnoses

  • Substance-Induced Mood Disorder: It's crucial to rule out substance use (e.g., cocaine, amphetamines, or other stimulants) that could induce manic or hypomanic symptoms. The patient's recent change in behavior and mood could potentially be substance-induced, which would require a different treatment approach.
  • Medical Conditions Causing Manic Symptoms: Certain medical conditions (e.g., hyperthyroidism, brain tumors) can cause manic or hypomanic symptoms. Although less common, these conditions must be considered and ruled out through appropriate medical evaluation.

• Rare Diagnoses

  • Cyclothymic Disorder: Characterized by periods of hypomanic symptoms alternating with periods of depressive symptoms that last at least 2 years; however, the symptoms do not meet diagnostic requirements for a hypomanic episode and a depressive episode. Given the patient's acute presentation, this chronic condition seems less likely.
  • Schizoaffective Disorder: Involves a period of at least 2 weeks where there are psychotic symptoms (hallucinations or delusions) in the absence of a major depressive or manic episode. The patient's presentation lacks mention of psychotic symptoms, making this diagnosis unlikely based on the provided information.