Complex sentence: This does not necessarily imply that a happy person is delusional or deny that some depressed individuals may be unrealistically negative (e.g. Pacini, Muir and Epstein, 1998).
Split into simpler sentences: This does not necessarily imply that a happy person is delusional. Also, depressed individuals can be unrealistically negative (e.g. Pacini, Muir and Epstein, 1998).