behavioral change in an elderly person

67 yr old female.  No apparent cognitive problems. Can still work puzzles & play sudoku.  Has been walking 4 miles most days.  Type II diabetic well controlled, has atrial fib.  Prior to 2 yrs ago was functioning very well .  Volunteered for social group projects.  Always outgoing.  Now diagnosed with depression.  Can't be left alone anymore. Behaviors seen are pulling out of hair, lying in floor as if throwing a temper tantrum, not wanting to go out in public. Is occasionally angry (frustration probably).  Has had all kinds of tests--no dementia supposedly.  She has lost more than 40 lbs over the past 9-12 mos.  Apparently no metabolic problems.  What are we missing as a clue to what is going on.  I believe it to be frontotemporal dementia as it mentions behavior changes even though she only meets two of those. Any help or guidance will be greatly appreciated.
Thank you

[ggreg]

I do not know if this will help, but if she has been treated for depression with SSRIs for a while, the doctor should review her medications.  I was on Lexapro and had a bad reaction to it, then went off it and threw stuff and became fearful.  I'm fine now.  I was in my late 50s when that happened.