Substance Use Disorders in Late Life: The Next Silver Tsunami

Over the next few decades the percentage of population of individuals 65 years and older in the United States is projected to increase from 13% to 25% of the total population [1]. These older adults are thought to be an at-risk population for psychoactive drug use [2]. Available evidence indicates that approximately one in four older adults has used a psychoactive medication with an abuse potential and it is postulated that by 2020 there will be approximately 2 million older adults with substance use disorders [3,4].


Introduction
Over the next few decades the percentage of population of individuals 65 years and older in the United States is projected to increase from 13% to 25% of the total population [1]. These older adults are thought to be an at-risk population for psychoactive drug use [2]. Available evidence indicates that approximately one in four older adults has used a psychoactive medication with an abuse potential and it is postulated that by 2020 there will be approximately 2 million older adults with substance use disorders [3,4].

Epidemiology
It is estimated that between one-quarter to one-half of individuals ≥ 65 years in age currently drink alcohol [5]. One national survey found that approximately 13% of older men and 8% of older women reported at-risk use of alcohol [6]. A recent national survey indicates that 14.1% individuals who are ≥65 years in age use tobacco [7]. Another national survey showed that 0.7% of adults aged ≥65 years used marijuana and 0.04% used cocaine within the past year whereas the numbers of older adults using inhalants, hallucinogens, methamphetamine and heroin was <0.2% [8]. It is noted that 3.3% of women and 0.8% of men aged ≥65 years who live in the community meet the DSM-IV criteria for past-year benzodiazepine dependence [9]. There is emerging evidence for the increase in non-medical use of opioids among older adults with a current prevalence rate of approximately 1.4% [10].

Risk factors and Outcomes
Risk factors for substance use among older adults include a previous history of substance abuse, comorbid psychiatric illness and the presence of cognitive impairment [11]. The mitigating factors include being currently married and having a religious affiliation.
The presence of substance use disorders in older adults is associated with worse medical outcomes and greater economic burden for care [3]. Long term use of psychoactive substances results in central nervous system adverse effects, the development of physiological dependence and the development of withdrawal symptoms when these drugs are discontinued abruptly. It can also result in the development of medical disorders including cardiac, hepatic and renal disease at rates greater than what are identified in younger individuals [12]. In addition, these individuals have greater rates of psychiatric disorders including depression, rates of suicides and dementia [13]. The overall cost to healthcare from substance use disorders in the United States is estimated to be over $100 billion per year with the associated cost for the care of older adults with substance use disorders being significantly higher due to the greater rates of comorbidities among these individuals [14].

Assessment
Unfortunately, substance use disorders among older individuals are poorly diagnosed [14]. Common barriers to the under-diagnosis include insufficient knowledge of these disorders, denial of the condition, stigma and/or the shame of using substances with abuse potential. In addition, reluctance to seek professional help, a lack of financial resources, lack of social support, the presence of comorbid conditions, limited time spent with primary care physicians and ageist attitudes towards mental health issues among older adults contributes to the inaccurate diagnosis these disorders. Furthermore, commonly used diagnostic criteria like the DSM-IV text revision (TR), tend to underestimate the prevalence of substance use disorders among older adults [15].

Treatments
Although available data indicates that older adults respond to substance use treatments as well as younger adults there is a dearth of controlled data for the management of substance use disorders in older adults [16]. However, it is recommends that brief intervention strategies and motivational counseling should be the initial step in the treatment of older individuals with substance use disorders [14]. Specialized treatment programs are reserved for cases where less intensive stratégies do produce the desired benefit. These treatments modalities should be non-confrontational and supportive with strategies that address age-specific psychological, social and health concerns having a greater chance of success among these individuals [2]. Although acamprosate, buprenorphine, bupropion, disulfiram, methadone, naltrexone, nicotine and varencline are US Food and Drug Administration (FDA)-approved medications to treat substance use disorders in younger individuals there are no drugs that are currently approved for use in older adults with substance use disorders [17].

Future Plans
If we are to improve the care of older adults with substance use disorders then there is an urgent need to refine the current diagnostic criteria to include provision for making age-appropriate diagnoses of substance use disorders. Additionally, screening instruments that are specific to the assessment of different types of substance use disorders in older individuals, such as the SMAST-G and AUDIT-5 should be used more frequently in clinical practice [18]. Furthermore, new interventions or medication trials specific to older adults will enable the development of evidence-based management protocols to optimize the care of these individuals. Multicomponent management strategies that have shown success in the care of older at-risk alcohol users should be extended to the care of older adults who use other psychoactive substances [19]. Majority of older adults with substance use disorders are evaluated by primary physicians. Hence the assessment of these individuals should begin in the primary care physician's office [20]. In addition, these individuals should receive close follow-up with frequent telephone contact from the clinic staff to motivate them to reduce their use of substances [21]. Furthermore, studies that evaluate means to improve access to healthcare will motivate older adults with substance use disorders to see treatment who might otherwise not seek treatment due to various psychosocial issues [22].

Conclusions
The population of older adults in the United States is growing at an appreciable rate and this phenomenon has been dubbed the 'Silver Tsunami. ' Associated with the growth of the aging population is the evidence for the significant growth of older adults who are using psychoactive substances. This substantial growth in the number of older adults who are using substances can be termed the 'Second Silver Tsunami. ' Current evidence indicates that the care of these individuals is limited, with poor healthcare outcomes and staggering cost of care. If we need to improve the care of these individuals, there is a urgent need to refine current diagnostic criteria, initiate new treatment trials and provide greater access to care for these individuals. By adapting a proactive strategy for the care of older adults with substance use disorders, we may not to prevent the 'Second Silver Tsunami' but at least we can mitigate its aftermath.