Article continues below advertisementMany psychologists remain certain Donald Trump is exhibiting a clear cognitive decline.Amid ongoing concerns about the president of the United States' health, Dr. John Gartner appeared for an interview on "The Daily Beast" podcast, where he claimed Trump has been displaying a "massive increase" in "clinical signs of dementia."The mental health professional argued that Trump's symptoms have only made his alleged "malignant narcissism" worse.Article continues below advertisementSource: MEGAThe president has been accused of having dementia.Dr.