India, with a population exceeding 1.3 billion, is witnessing a significant demographic shift towards an aging society. As of now, Indian adults aged 60 years and older number over 138 million, a figure that is expected to surge, making up 20% of the country’s population by 2050. This shift is largely attributed to longer life expectancy and advancements in healthcare, which, while contributing to a higher number of older adults, also brings to the forefront the prevalence of age-associated diseases and conditions, including dementia, a major public health concern globally and especially pronounced in low and middle-income countries.
Dementia, characterized by a decline in memory, thinking, behavior, and the ability to perform everyday activities, has become a focal point of research and public health planning. The complexity of diagnosing dementia has led to the development of various approaches in population-based studies, ranging from resource-intensive clinical adjudication to the creation of algorithms based on a priori criteria. Notably, algorithms incorporating neuropsychological testing with robust norms have demonstrated greater stability over time and are associated with a lower rate of false-positive classifications.
Historically, estimates of dementia prevalence in India have varied. The use of the 10/66 algorithmic criteria, which sets cutoffs on standardized cognitive testing and evaluations of everyday functioning, indicated a prevalence ranging from 7.5% in urban areas to 10.6% in rural regions. However, these figures contrast with other studies reporting a prevalence between 2.2% to 14.9%, often based on convenience samples or those with geographic limitations.
A groundbreaking study by Lee and colleagues, utilizing a nationally representative sample, estimated the dementia prevalence at 7.4% through a prediction algorithm informed by the Clinical Dementia Rating (CDR). This highlights the significance of employing a recognized clinical diagnostic authority like the Diagnostic and Statistical Manual of Mental Disorders (DSM, 5th ed), which offers a comprehensive framework for diagnosing neurocognitive disorders by documenting cognitive decline, assessing independence in everyday activities, and ruling out other conditions.
The transition from DSM-IV to DSM-5 criteria marks a significant shift in the diagnostic approach to dementia. Unlike DSM-IV, which required impairment in memory and another cognitive domain, DSM-5 adopts a more inclusive criterion, recognizing cognitive impairment in any domain. Moreover, DSM-5 emphasizes the impact of cognitive deficits on independence in everyday activities, a change from the previous requirement of a significant decline from a prior level, a criterion that proved challenging to assess in older Indian adults.
The present study endeavors to elucidate the prevalence of mild and major neurocognitive disorders in India, employing a diagnostic algorithm based on DSM-5 criteria. Through a comprehensive analysis, the study reports on overall dementia prevalence rates, investigates the relationship between self-reported memory issues and the risk of diagnosis, and compares DSM-5 classifications with clinically adjudicated CDR scores in a subset of participants. This research not only contributes to a deeper understanding of dementia’s impact in India but also underscores the importance of adapting diagnostic criteria to better suit the population’s unique characteristics, thereby paving the way for more effective public health strategies and interventions in the face of an aging population.
Table summarizing the key information from the provided text:
|Longitudinal Aging Study in India-Diagnostic Assessment of Dementia (LASI-DAD)
|Population Age Range
|60 to 104 years
|– 43% of women reported no formal education – Majority residing in urban settings
|– 12% reported severe loss in at least one Activity of Daily Living (ADL) – 8.5% reported impairment in any Instrumental Activity of Daily Living (IADL)
|– Higher mean cognitive scores observed in younger, educated, literate, and urban residents – Substantial overlap in cognitive scores across the sample – Younger-generation informants more likely to report discrepancies in IADL and ADL difficulties
|Prevalence of Neurocognitive Disorders
|– Unweighted prevalence: Major neurocognitive disorder: 8.5%, Mild neurocognitive disorder: 17.4% – Adjusted for sampling weights: Major neurocognitive disorder: 7.2%, Mild neurocognitive disorder: 17.6% – Prevalence increases with age and decreases with higher education
|Relationship with Self-reported Memory Decline
|Participants reporting worsened memory had significantly higher odds of being diagnosed with mild or major neurocognitive disorders
|Comparison of DSM-5 and CDR
|– High concordance between DSM-5 classifications and Clinical Dementia Rating (CDR) scores – Specificity: 0.93, Sensitivity: 0.66 – Some cases identified through CDR were not classified as major neurocognitive disorder by DSM-5 criteria
|Challenges in Diagnosis
|– Discrepancies between CDR ratings and DSM-5 classifications noted – Discordance in subscale scores among clinician raters – Potential for misclassification, especially among older and rural populations
|– Highlighted demographic, educational, and gender disparities – Identified diagnostic challenges – Laid groundwork for targeted public health strategies and interventions aimed at mitigating the impact of neurocognitive disorders among India’s aging population
This table organizes the information provided in the text into clear categories, allowing for easy reference and understanding of the LASI-DAD study’s key findings and implications.
Understanding Dementia Prevalence in India: Insights from the LASI-DAD Study
The Longitudinal Aging Study in India-Diagnostic Assessment of Dementia (LASI-DAD) provides a comprehensive overview of the prevalence and characteristics of dementia in the Indian elderly population, which ranges in age from 60 to 104 years. This pivotal study casts light on the demographic makeup, cognitive health status, and the stark reality of neurocognitive disorders among India’s aging population. With a significant portion of the sample aged between 60 and 79 years and a mean age of 69 years, the LASI-DAD sample underscores the urgency in addressing cognitive impairments within this demographic.
Key findings from the study reveal that 51% of the weighted sample comprises women, 43% of whom report no formal education, with a majority residing in urban settings. This demographic detail is crucial as it highlights the gender and educational disparities that could potentially influence the prevalence and management of dementia. Notably, 12% of the sample reported severe loss in at least one Activity of Daily Living (ADL), and 8.5% reported impairment in any Instrumental Activity of Daily Living (IADL), indicating a significant portion of the elderly population is already experiencing considerable functional decline.
The study utilized a robust normative sample of 2,513 participants, which was more likely to comprise younger, educated, literate, and urban residents. This subgroup displayed higher mean cognitive scores than those not included, although there was substantial overlap in cognitive scores across the sample. Interestingly, the study found that younger-generation informants were more likely to report discrepancies in IADL and ADL difficulties, suggesting generational differences in the perception of cognitive and functional impairments.
In terms of overall prevalence, the study reported an unweighted prevalence of DSM-5 major and mild neurocognitive disorder at 8.5% and 17.4%, respectively. When adjusted for the sampling weights, these figures translate to a population prevalence of 7.2% for major neurocognitive disorder and 17.6% for mild neurocognitive disorder. These findings are significant, as they offer a granular view of the cognitive health landscape among India’s elderly, providing a baseline for public health interventions.
The prevalence of major neurocognitive disorder increases with age and decreases with higher levels of education. For instance, prevalence rates ranged from 3.8% among those aged 60–64 years to 15.2% among those aged 80 years and older. Additionally, the prevalence was higher among those with no formal education (10.8%) compared to those with tertiary or higher education (3.5%). This trend was consistent for both major and mild neurocognitive disorders, suggesting that age and education are significant predictors of cognitive decline.
The study also explored the relationship between self-reported memory decline and neurocognitive disorder prevalence. Participants reporting worsened memory had significantly higher odds of being diagnosed with mild or major neurocognitive disorders, highlighting the importance of subjective cognitive complaints as potential early indicators of neurocognitive decline.
A critical aspect of the LASI-DAD study was the comparison of DSM-5 classifications with Clinical Dementia Rating (CDR) scores. The analysis showed a high degree of concordance between DSM-5 classifications and CDR scores, with a specificity of 0.93, indicating few false positives. However, the sensitivity was 0.66, suggesting that some cases of dementia identified through CDR were not classified as major neurocognitive disorder by DSM-5 criteria.
The study’s detailed analysis of discrepancies between CDR ratings and DSM-5 classifications sheds light on the challenges in diagnosing dementia accurately. For participants unimpaired according to CDR but diagnosed with major neurocognitive disorder by DSM-5, there were notable disagreements among clinician raters on subscale scores. This discordance underscores the complexity of dementia diagnosis and the potential for misclassification, particularly among older and rural populations.
The LASI-DAD study’s findings are a crucial step forward in understanding the prevalence and characteristics of dementia in India’s elderly population. By highlighting the demographic, educational, and gender disparities, along with the diagnostic challenges, this study lays the groundwork for targeted public health strategies and interventions aimed at mitigating the impact of neurocognitive disorders among India’s aging population.
reference link : https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0297220