Here are some more reasons why your parents might be complaining too much:
Infections can be Devastating to an Elder
A bladder infection (UTI) can cause havoc with their personalities and other issues, even when there is no obvious physical sign that there is an infection present.
Pain Makes Nearly Everyone Crabby
If your elder was doing quite well, but suddenly changes into an irritable complainer, make sure the elder sees a doctor to check for painful changes in his or her health. Many elders "don't want to complain," so they don't go to a doctor. Yet they unknowingly complain to their families all day long. Which brings me to the next reason for complaints.Some people feel that age gives them a right to complain
When people are in the workforce or have more outside activity, they may feel they have to rein in their negative side. Once they are retired and/or are just around the house with less responsibility, they may feel they've "earned" the right to say exactly what they feel. And much of what they feel could be negative if they are bored or feeling unneeded. If your elder has this attitude, he or she may actually be able to understand what this switch of attitude is doing to the family. There may be hope that they can be changed.
Some People may be Developing Dementia
Memory issues are generally what people look for when they think of dementia, and of course memory issues will be part of dementia. However, some people are so good at covering up their memory problems – or have a spouse that covers for them – that memory problems can go unnoticed by family members until the issue is quite severe.
However the frustration the elder feels over memory problems, coupled with getting lost or not being able to recognize familiar objects, can cause startling personality changes. Alzheimer's disease, Pick's disease and other dementias often bring about personality changes. These people need to see a doctor as soon as possible.
Some People were Always Controlling and Abusive
Unfortunately, a significant number of adults grew up in dysfunctional families where they were abused, physically and/or emotionally, all of their lives. Just because their parents grow old doesn't mean there will be any positive changes in the dynamics. Unless the abusers got counseling or other help along the way, they will likely be just as abusive to their adult children as they were to these same children when they were small.