While being sad or experiencing a shift in mood can happen to almost anyone occasionally, mood and personality changes may be early indicators of serious health issues. These can include mental health conditions, hormonal changes, or substance abuse problems. When those with dementia experience these symptoms, they can manifest as fear, suspicion, and getting easily upset or becoming irritable over minor things. Not wanting to participate in social activities once enjoyed, like golf or going to church, may be a sign of dementia.