When wondering if your senior loved might be suffering from dementia, the reality is another condition often mimics dementia including depression. There are some key differences to help determine whether your loved one is suffering from dementia or depression. Although dementia and depression both include a decline in mental functioning, dementia is gradual and depression is rapid. They both include memory difficulties but dementia is difficulty with short-term memory while depression is actually just a concentration problem. Another difference is awareness on date, time and environment. Dementia patients can have confusion on the date, time and environment while depression does not.