Isolation
For those who have grown up relying on hearing for communication, learning and social contact, losing hearing results in social isolation.
Adults with untreated hearing loss tend to withdraw from engaging with family and friends.
Adults aged 50 and over are more likely to report depression, anxiety, anger frustration, emotional instability and paranoia, and are less likely to participate in social activities than those who wear hearing aids.
https://vestibular.org/news/09-13-2012/link-between-untreated-hearing-loss-mental-health
Depression
Untreated hearing loss gives rise to poorer quality of life, isolation and reduced social activity, leading to depression.
Cognitive Decline
Adults with untreated hearing loss are more likely to develop problems thinking and remembering, than adults whose hearing is normal.
Degraded hearing may force the brain to devote too much of its energy to processing sound.
Those with untreated hearing loss experience a 30-40% greater decline in thinking abilities compared to those without hearing loss
Adults with untreated hearing loss develop a significant impairment in their cognitive abilities 3.2 years earlier than those with normal hearing.
Lin F et al, 2013, Hearing loss and cognitive decline in older adults. JAMA Intern Med.173,4; 293-299.