SN instructed that the dementia symptoms vary depending on the cause, but common signs and symptoms include: Cognitive changes: Memory loss, difficulty communicating or finding words, difficulty with complex tasks, difficulty with planning and organizing, difficulty with coordination and motor functions, problems with disorientation, such as getting lost. Psychological changes like personality changes, inability to reason, inappropriate behavior, paranoia, agitation, hallucinations. Memantine (Namenda) works by regulating the activity of glutamate. Glutamate is another chemical messenger involved in brain functions, such as learning and memory. A common side effect of memantine is dizziness.