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ORIGINAL ARTICLE
Year : 2022 | Volume
: 28
| Issue : 4 | Page : 275-278
Association between hearing loss and dementia in elderly
Devika Sinha, Rajeshwary Aroor, Vadisha Srinivas Bhat, Marina Saldanha, Srinath DP Kamath, Shashank Kotian
Department of Otorhinolaryngology, KS Hegde Medical Academy, Nitte (Deemed to be) University, Mangalore, Karnataka, India
Correspondence Address:
Dr. Rajeshwary Aroor
Department of Otorhinolaryngology, KS Hegde Medical Academy, Nitte (Deemed to be) University, Mangalore, Karnataka
India
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/indianjotol.indianjotol_68_21
Background: Long standing hearing-loss often leads to the setting in of dementia as hearing-loss. In this study, elderly population were screened for hearing-loss and dementia using Hindi-Mental State Examination. Aims: To know the association between the dementia and Hearing loss Method 206 participants in the age group of 60-80 years (110 were females and 96 were males) were subjected to audiological evaluation and dementia screening using HMSE dementia scoring scale and it was compared with hearing level. Results: Out of 206 subjects, 110 were females and 96 were males. Right ear hearing-loss was seen in 147 cases and left ear in 130 cases. 48 individuals had no hearing-loss, 39 participants had unilateral hearing-loss and 119 participants had bilateral hearing-loss. Most common type of hearing-loss observed was mild hearing-loss 124 participants had no dementia, 82 had dementia. 60 had mild cognitive impairment and 22 had severe cognitive impairment. 49 out of 82 participants with dementia had bilateral hearing-loss. As the hearing handicap percentage increases from 1-100, dementia score decreases. But it was not statistically significant. More number of men were affected with hearing-loss but more number of female participants had dementia. Conclusion: Hearing-loss is more common in men in elderly population but dementia is more commonly seen in females.
Keywords: Dementia, elderly, hearing loss
Normal hearing is required to learn language, communicate, work, and socialize. It helps us to stay connected with outside world and keeps us safe by warning us of potential danger. Hearing loss in the elderly is a matter of concern. It is often neglected and left untreated. Around 5.3% of the world population suffers from hearing loss.[1] The risk of hearing loss increases with age (age-related hearing loss [ARHL]), 40% of the individuals above the age of 65,[2] and 75% individual older than 80 years[3] suffer from hearing loss. ARHL, also known as presbycusis, is a progressive, bilateral and symmetrical hearing loss and is primarily observed in the high-frequency region. Long-standing hearing loss in them leads to social isolation because they are not able to understand the daily conversations and hence isolate themselves from social interactions. This may lead to the setting in of dementia. Dementia is a leading cause of disability in the world affecting 6.5% of the population above 65 years of age.[4],[5] There is disturbance of multiple higher cortical functions, including memory, thinking, orientation, comprehension, calculation, learning capacity, language, and judgment. Consciousness is not clouded. The impairments of cognitive function are commonly accompanied, and occasionally preceded, by deterioration in emotional control, social behavior, or motivation. Dementia and hearing loss are both highly prevalent in older adults, each having considerable impact on quality of life.[6],[7] Therefore, in this study, we tried to study the association between hearing loss and dementia by evaluating the elderly population for hearing loss and screening them for any dementia using Hindi Mental State Examination (HMSE).[8]
MethodsAfter informed consent, 206 participants in the age group of 60–80 years who were willing to participate in the study were subjected to audiological evaluation using AC-40 pure tone audiometer to find the baseline hearing levels of both the ears at 500, 1000, 2000, 4000 Hz. Individuals with preexisting neurological conditions such as Alzheimer's disease, Parkinson's disease, organic cause for dementia altered level of sensorium were excluded from study. Individuals who were not able to follow the commands were also excluded.
An average of all the four frequencies was taken as hearing level of that particular ear. Hearing level of 25 dB and above, in the speech frequency, was considered as hearing loss. Depending on the hearing level of the participants, they were further classified into normal hearing and hearing loss groups. In those with bilateral hearing loss, a hearing handicap percentage was calculated.
All the participants were further subjected to dementia screening using HMSE[8] in their vernacular language. Based on the score obtained, they were categorized as having dementia or no dementia. The score between 24 and 31 is considered normal, 17–23 indicates mild cognitive impairment, and 0–16 is severe cognitive impairment. If a patient was found to have dementia based on the score obtained, he/she was referred to the Department of Psychiatry for further management.
Ethical clearance
Ethical approval for this study (INST.EC/EC/098/2018-19) was provided by the Ethical Committee of KS Hegde Medical academy, Nithyanandanagar, Mangalore, on 22 October 2018.
ResultsOut of 206 subjects, 110 were females and 96 were males. Maximum number of participants in our study were females, and they were in the age group of 60–64 years followed by 65–69 years.
Right ear hearing loss was seen in 147 cases and left ear in 130 cases.
Out of 206 participants, 48 individuals had no hearing loss (hearing level ≤25 dB), 39 participants had unilateral or one-sided hearing loss, and 119 participants had bilateral hearing loss. Most common type of hearing loss observed was mild hearing loss (127 out of 412 ears) in both right and left ear [Table 1].
124 participants (69.9%) had no dementia, 82 had dementia. 60 (19.4%) out of total participants had mild cognitive impairment, and 22 (10.7%) had severe cognitive impairment. Among the participants with dementia, most number of individuals (52) were in the age group of 65–74 years.
49 out of 82 participants with dementia had bilateral hearing loss [Table 2]. As the hearing handicap percentage increases from 1 to 100, HMSE score decreases. However, it was not statistically significant when Mann–Whitney U-test was used. When hearing handicap percentage was compared with HMSE score in individuals with bilateral hearing loss, it was observed that the lowest dementia score (22) was in the category of individuals with maximum hearing handicap % (81–100). Most of the individuals belonged to the category of 1–20 of hearing handicap % [Table 3].
Table 2: Distribution of dementia according to bilateral hearing loss (unilateral hearing loss patients were considered to be normal as hearing handicap percentage calculation is only for bilateral hearing loss)
Table 3: Distribution of hearing handicap percentage and Hindi Mental State Examination scoresMore number of men were affected with hearing loss but more number of female participants had dementia (49) compared to males (33) [Table 4]. The female gender had lower HMSE scores compared to the males in unilateral right-sided hearing loss, bilateral hearing loss, and those with normal hearing.
DiscussionThe advancements in health-care facilities and its accessibility to individuals of all strata of society have led to a gradual increase in life span of human beings. Dementia and age related disorders are common in elderly. Dementia can lead to significant disability, morbidity, mortality, and an increased expenditure on health care. The social and financial burden of dementia and hearing loss is rising rapidly with aging.[9] Early detection of risk factors and identifying causes of dementia can help to reduce the burden of the disease. It has been observed and studied that hearing loss can give rise to dementia. The hearing loss may lead to auditory volume loss in the brain.[10],[11] It can also cause accelerated atrophy in certain areas of the brain.[10] Hence, detecting hearing loss on time and taking preventive and curative measures can help to reduce the occurrence of dementia and cognitive impairment. Majority of elderly people suffer from ARHL. These individuals suffer from social isolation because of not being able to actively participate in the conversations. This social isolation can lead to early occurrence of dementia and other cognitive impairment. Therefore, there is a need to identify this hearing loss on time so that appropriate interventions can be taken up to treat it or prevent it from getting worse and in turn preventing dementia from setting in.
In our study, we tried to find an association between hearing loss and dementia in elderly individuals. Using HMSE, dementia scores of individuals with unilateral and bilateral hearing loss were measured and compared with the normal individuals. The majority of participants in our study were in the age group of 60–69 years, females were more than males in all age groups. Mini–Mental State Examination is the most widely used to screen dementia.[12] HMSE is more convenient to use in Indian scenario as it is simple and does not contain any subtraction or calculation.[8],[13]
In this study, female participants were more compared to males, similar results were observed in other studies.[14] This could be because of the increased life expectancy among the females compared to males.[15] Mild hearing loss was the most prevalent level of hearing loss in elderly.[14],[16] We also found in our study that mild hearing loss was more as compared to other grades of hearing loss. 127 (right 68+ left 59) out of 412 ears had mild hearing loss. Age distribution of our study shows the decline in the number of participants as age advances which corresponds to the age distribution in general population. In majority of the elderly population, hearing loss is taken as granted and considered as part of aging process and often neglected. The elderly population in the age group of 60–70 are usually not dependent on their family members for hospital visits compared to the more advanced age group. This may be the other reason for more number of participants in the age group of 60–64 followed by 65–70.
Right ear was more affected than the left ear.[17] Even in our study, right ear hearing loss was more compared to the left ear both in unilateral and bilateral hearing loss cases. Overall involvement of right ear was seen in 147 participants whereas left ear involvement in 130 cases. In unilateral hearing loss, right side was involved in 28 participants whereas left side in only 11. Hearing impairment can cause reduction in the whole brain volume, especially the right temporal region, over a period of 6.4 years.[10]
Unilateral right ear hearing loss was seen more in females compared to bilateral and unilateral left-sided hearing loss. Although females were more in our study, hearing loss was more commonly seen in men. It has been observed that hearing loss was more in men compared to women.[18] According to Pearson et al.,[19] hearing impairment occurs at a faster rate in men when compared to women at all ages and frequencies. This could be the possible explanation of males more affected with hearing loss in our study population, even though we had more number of females in our sample. Men when compared to women are more exposed to environmental sounds owing to their nature of profession, such as driving, working in factories, and military.
A total of 82 individuals in this study showed dementia (mild and severe) while 124 of them had normal cognitive functioning. 49 out of those 82 had bilateral hearing loss (P = 0.638), whereas 33 did not have bilateral hearing loss (either normal hearing or unilateral hearing loss). Unilateral hearing loss individuals were considered as normal as it does not give rise to major disability. The hearing loss individuals are more prone to all-cause dementia (dementia secondary to any cause).[20] Over the age of 65 years, the mean time for developing dementia was 10.3 years in those with hearing loss at baseline versus 11.9 years for counterparts with normal hearing.[21] People with mild, moderate, severe hearing loss were found to have twice, thrice and 5 times the risk of developing dementia, respectively.[20],[22]
The median dementia score of both bilateral and unilateral hearing loss groups is 26 and P = 0.921. Even in bilateral hearing loss individuals when compared with the normal hearing individuals, there is no significant difference in dementia score (P = 0.702). There is no significant difference between the dementia score of right-sided hearing loss compared to the left-sided hearing loss.
Female gender was more prone to develop dementia, even we have observed the same.[23],[24] When dementia scores of men were compared with that of women, no significant differences were observed in both unilateral, bilateral hearing losses, and normal hearing participants. We feel that the reason for no difference in dementia scores among these groups is probably due to majority of our study population being in mild hearing loss category which does not give rise to major disability.
We have observed that as the hearing handicap % increases, dementia score decreases. Majority of mild and severe dementia cases were in the age group of 65–74 years. Younger individuals with hearing loss are more prone to develop dementia.[25] Liu and Lee in their study found that lower age group participants were at a higher risk of developing dementia.[26] The median dementia score of participants with hearing handicap grading from one to 20 was 26, whereas for 81–100 it was 22, in this study. In our study population, maximum number of participants were in the minimum hearing handicap group (one to 20), compared to the severe hearing handicap group. This is probably due to majority of our study population were in 60–64 age group and majority of them had mild hearing loss. Difficulty in communicating with the severely handicapped participants may be the other cause for less number of participants in severely handicapped group, as these individuals were excluded from the study.
We also observed that even though a greater number of male participants had hearing loss compared to females, higher number of female participants had dementia. Su et al.[23] and Mick et al.[24] who studied the association of social isolation with hearing loss also concluded that female gender was more prone to develop dementia.
ConclusionHearing loss is more common in men compared to females in elderly population, but dementia is more commonly seen in females. Majority of them suffer from mild hearing loss. We would like to conclude that hearing loss is a risk factor for dementia in elderly population, as the hearing handicap percentage increases, dementia score (HMSE score) decreases though statistical significance could not be established. Early detection of hearing loss and intervention may prevent the cognitive impairment in the elderly and improve the quality of life. A larger series in future followed up on a long-term basis may give us more accurate results.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References
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