DEPRESSION
-Apathy
-Inability to Feel Pleasure
-Guilt
-Hopelessness
-Sadness
-Excess Sleepiness
-Social Isolation
ADHD
-Repetition of Words
-Forgetfulness
-Difficulty Focusing
-Boredom
-Short Attention
-Poor Organization
-Poor Listening
ANXIETY
-Hypervigilance
-Sweating
-Excessive Worry
-Unwanted Thoughts
-Nausea
-Racing Thoughts
-Depression
-Loss of Appetite
-Mood Swings
-Aggression
-Fatigue
-Gain of Appetite
-Restlessness
-Impending Doom
-Fidgeting
-Procrastination
Impulsivity
-Anxiety
-Agitation
-Irritability
-Poor Conc
-Anger
-Fear
Relationship of Mental Illnesses
As you can see, these different, but connected, mental illnesses share many of the same symptoms. These seem to compound and increase each other's effects, and make it harder to determine the origin of these emotions.
This diagram shows that, while these three illnesses are very similar, they are irrevocably different. Each holds their own, individual symptoms that mix with the others to form a complicated mental storm.