Hello and Happy New Year

I am here because I am really really confuse by my mother situation. It started with depression about 3 years ago, it got so sever that had to be admitted to psch unite for electronic shock a year ago and medications. Although she has improved but my biggest confusion is that she has selective talking, if there is food on the table she eats them all without any control. At the table she is the 1st one who finishes food very fast, when we ask do you want more she says no. But after some time she tries to eat of my brothers dish. Also, she wants to sleep alot or go to bed alot. Her MRI is negative. She used to be most talkative in our family, happy, brings energy and light to home. Since she has been sick, our home is very very dark. I am very confuse. Is this more than depression, if it what could it be? Could be picks? is it Alzheimer? How can I rule out?

Thanks for your support in advance.
Sara