Background
Dizziness is a common disabling symptom among elderly adults [
1,
2]. It is defined as a subjective feeling of the illusion of movement, a disorientation of the body in space or postural instability [
3,
4]. Some population-based studies have reported that the prevalence of dizziness in elderly people ranges from 11% to 39% and significantly increases with age [
1,
3,
5]. Data from the National Health and Nutrition examination Survey Study (NHAES) with US adults aged 40 years and older showed that the prevalence of vestibular dysfunction was 49.4%, 68.7% and 84.8% at ages 60–69, 70–79 and 80 and over, respectively [
6].
Clinical and social conditions associated with dizziness are heterogeneous, making the identification of underlying causes sometimes ineffective [
4,
7,
8]. In about 40% of dizzy patients after one year of follow-up, family doctors were still unable to specify a diagnosis, treating the complaint of dizziness or vertigo as a diagnosis [
9].
Dizziness is a strong predictor of falls, recurring falls [
6,
10] and disability in elderly adults [
1,
2]. Several health, psychological and social characteristics were observed in association with a report of dizziness in elderly adults living in the community, such as age [
3,
6], female gender [
3,
5,
6], low educational level [
6], anxiety [
11] and depression or depressive symptoms [
3,
5,
11], past myocardial infarction, postural hypotension [
11] and cardiovascular disease [
3], diabetes [
6], poor hearing and vision [
5,
11], using a large number of medications [
3,
11], having three or more diseases [
3], poor self-health rate [
3] and balance and gait disorders [
3,
11]. Among patients that visited their family physicians due to dizziness it was found that living alone, having little education and presenting cardiovascular disease and hypertension increased the chances of reporting dizziness [
9].
Due to its unspecific and complex manifestation in elderly people, dizziness has been considered either a geriatric syndrome [
11‐
13] or a geriatric condition [
14], both of them characterized as a multifactorial health condition not related to a specific disease. Despite its similarity, a geriatric syndrome distinguishes from a geriatric condition in its conceptual framework. If dizziness is to be considered a geriatric syndrome it is expected to be age-dependent, to have multiple risk factors and might be correlated with other syndromes, such as falls, frailty and disability. Health care practitioners are faced with the challenge of looking for its underlying causes and, mainly, identifying treatable dizziness-related conditions. A profile of dizziness in elderly adults is still uncertain [
15]. We conducted this study to explore the interrelations between dizziness and a broad range of health and geriatric conditions, diseases, geriatric syndromes and demographic characteristics in a representative sample of community-dwelling elderly people.
Discussion
This study can be considered one of the first ones to investigate dizziness in a representative sample of elderly adults living in the community in a developing country. We observed a higher prevalence of dizziness when compared with other population-based studies [
4,
5,
11]. It is suspected that this prevalence difference is due to the heterogeneity on the scope of the questions used to identify participants with dizziness in population-based studies [
3,
29]. Elderly adults with depressive symptoms, perceived fatigue, excessive sleepiness and recurring falls were more likely to report dizziness in the past year. Among the outcomes in the final model, the presence of five or more depressive symptoms was the main contributor for reporting dizziness, followed by falls and fatigue. Our findings suggest that dizziness in community-dwelling elderly adults might be considered a complex geriatric condition, rather than a geriatric syndrome which co-occurs and interacts with other common conditions in elderly adults, exposing them to adverse health events, such as recurring falls.
Unexpectedly, we observed a lack of association between advancing age and dizziness. However, other important studies have come across with this same outcome [
5,
11,
13]. We noticed a slight but not significant increase in the prevalence of dizziness among the young old, but after the age of 75 the occurrence of dizziness decreased and this trend was mainly detected for women. Also in our sample the oldest participants were quite healthy. Only 5.6% of then reported to have a poor or very poor health, which could in part explain this lack of association. It also has been discussed that dizziness might be age-concomitant rather than age-dependent [
30].
Curiously, dizziness interacted with fatigue, sleepiness and depressive symptoms that are clinically heterogeneous geriatric conditions, which are likely to share some etiological factors and pathological pathways [
11‐
13]. Fatigue can be considered a symptomatic manifestation of several subclinical diseases and is related, in the elderly, to an increased state of chronic inflammation, physiological dysregulation or an increased workload to maintain homeostasis [
31], suggesting that it represents a general state of physiological change, and, ultimately, may be a marker of declined functional reserve in the aging [
32] .It has been reported that fatigue can be a secondary problem among patients with vestibular pathology, together with muscular pain and increased muscle tension and chronic anxiety [
33]. Hardy and Studenski studied five qualities of fatigue among older adults with chronic conditions and identified that a substantial prevalence of participants (70%) reported any type of fatigue. Additionally, the majority of participants complaining of fatigue reported multiple qualities (emotional, cognitive, sleepiness, low energy, weakness and tiredness) despite the present chronic disease [
34]. We suggest that dizziness and fatigue co-occur and may be expressed in different combinations of symptoms, becoming complex geriatric conditions with a common underlying process, such as increased inflammation or disordered homeostasis [
34] rather than a discrete condition.
Regarding, the association between excessive sleepiness and dizziness the rationale is much more unclear. Literature is relatively uncertain about the true clinical meaning of excessive sleepiness among the elderly. It is often seen as a non-specific complaint and closely related to depression [
35]. In a prospective cohort study excessive day time sleepiness predicted the incidence of depression, appearing as a vulnerability factor for acute and chronic depressive episodes. However, a recent, case controlled study which followed patients in tertiary outpatient otoneurology clinic found that there was a significant association between idiopathic dizziness, excessive sleepiness and sleep apnoea. Nearly 39% of the patients with excessive sleepiness, identified through the
Epworth Sleepiness Scale (>10 points), had idiopathic dizziness compared to 14.7% in the control group [
36]. In another study in which the impact of excessive daytime sleepiness on the functionality of elderly persons was analyzed the authors suggested that disability resulting from sleepiness was not primarily linked to depression or dementia, as these elderly persons were carefully excluded from the sample, together with those with any other clinical conditions that could possibly hamper functionality [
37]. There seems to be an independent relation between dizziness, drowsiness and fatigue, however the aetiology of these relations remains obscure. It is worth noticing that the use of specific medications may have some effect on the association between dizziness, fatigue and drowsiness. In a recent cross-sectional study it was identified that dizziness and fatigue were among the clinical complaints or reasons for elderly adults’ hospitalization, possibly associated with inappropriate use of medications [
38]. However, in a large epidemiology study in Sweden, the use of number of medications in addition to the use of specific medications and diseases was associated with dizziness and faintness [
29].
It was observed that depression measured by the presence of depressive symptoms was strongly associated with dizziness in our study and was the main contributing factor in our final model. There is a well-known association between vestibular dysfunction and depression [
3,
5,
11,
39]. Elderly people with more depressive symptoms are more likely to have dizziness when compared to those with fewer symptoms [
3,
11] Elderly people with dizziness tend to have some consequences such as decreased functional performance in daily activities, anxiety and insecurity, which can, in time, change their mood, increasing the chances of depression. Additionally, the relationship between dizziness and depression is complex and can also be partly explained by the adverse effect of antidepressant medications.
We observed that participants with dizziness were twice as likely to report recurring falls in the previous year compared with those who had a single fall or no fall at all. Dizziness was identified as a strong predictor of recurring falls in the elderly [
10,
40,
41] and its underlying mechanism is likely to be a consequence of a cumulative decrease in the physiological systems related to balance and postural control, mainly in the vestibular system, which, ultimately, can be affected by age itself, as well as by a variety of vestibular disorders. It has been suggested that the effect of age on postural instability may be, in part, mediated by vestibular dysfunction [
6].
Pre-frail and non-frail elderly adults were more likely to report dizziness, but this association was no longer observed when other outcomes entered in the final model. Curiously, the association with dizziness was not observed in the frail participants, supposedly the most vulnerable group. Recently, Dros et al. [
15] conducted an analysis of the main components to establish a classification of diagnostic profiles of dizziness based on empirical data and identified six components and frailty accounted for the biggest total variance, followed by the psychological and cardiovascular ones. However the authors highlighted that most patients were classified in more than one profile, signalizing the co-occurrence of many dizziness related-factors. We used the Fried phenotype, which is based on large physical components and is not expected to cover all possible manifestations of frailty in elderly adults [
42]. Some studies have shown a strong evidence that disability is independently associated with dizziness [
1,
2] but we did not observe this in our study. We suspect that the instrument that we used was not capable of capturing those elderly adults with a less severe disability status, since the Katz instrument measures the need for assistance to perform basic daily activities. Aggarwal et al. [
1] have also found a higher association between dizziness and disability in the Rosow-Breslau and Nagi measures, but not in the Katz ADL Scale.
As for disease, we did not observe any association between hypertension or cardiovascular disease and dizziness. This association has been more commonly identified among patients seeking medical assistance [
9,
13] than in elderly adults living in the community [
6].
We tried to identify if some outcomes of health inequality were associated with dizziness, since this is one of the first studies to explore this health condition in a developing country; however, no significant differences in social-demographic variables were identified between those who reported dizziness and those who did not. There is some discrepancy in the literature concerning the association between dizziness and demographic outcomes. Some studies have identified the association between age and gender[
1,
3,
9] with dizziness, but not others [
2,
5] and a relationship between dizziness and the educational level [
6] has also been observed, but none with wealth [
5].
Our study has a cross-sectional design limitation, preventing the establishment of relationships between causality and estimation of risk and we did not investigate the type of medications the participants were taking profoundly, either. Furthermore, there could possibly be a memory bias, since participants were asked to report dizziness at any time in the previous year. The identification of fatigue based on questions from an instrument developed to identify depression may also have increased the chances of association with dizziness. Nevertheless, these two questions of the CED-S have been systematically used in the literature to measure fatigue/exhaustion in elderly adults [
43,
44]. The strength of this study lies on the fact that it was a population-based study that investigated the complaint of dizziness in a representative sample of community-dwelling elderly persons using a comprehensive range of outcomes and explored the several symptoms related to dizziness.
Due to its interaction with other complex complaints and health conditions we suggest that dizziness in elderly adults is a multifactorial geriatric health condition and health care practitioners should conduct a comprehensive assessment in other to identify its associated conditions, together with strategies to investigate the underlying cause-related specific diseases.
Competing interests
The authors declare no conflicts of interest.
Authors’ contributions
SAM, WJSS, EF and MRP were responsible for data acquisition and data analysis and interpretation, drafting the article and final approval of the manuscript. MRP and EF were local coordinators of the multicentre study and also responsible for general supervision of the research group. EF was one of the coordinators for the FIBRA Study nationally and responsible for the acquisition of funding. All authors read and approved the final manuscript.