In the Spirit of Ambrose Bierce’s The Devil’s Dictionary

Promotional dementia, n. A mental disorder occurring when an individual within a company, corporation, or organization receives a promotion—an award that generally increases the person’s responsibility and possibly salary—and causes the individual to develop one or more of the following symptoms: increasing irrationality; mood swings; delusions of grandeur; decreasing use of common sense; memory loss; and alienation from his or her subordinates.
Bob may have promotional dementia because ever since he received that promotion he has ignored his friends at work, yells at anyone who goes into his office after inviting them in, and has forgot about the raise that I asked for.
Note: Promotional dementia may increase exponentially with each promotion.Ambrose Bierce