Untreated depressive symptoms significantly worsen quality of life in old age and may lead to the misdiagnosis of dementia: a cross-sectional study

In our aging society, not only the maintenance of health of old people, but also the restoration of their Quality of Life (QoL) has become an important goal. Therefore, many studies aimed to detect factors influencing QoL, as those may have preventive and therapeutic significance. Several studies have demonstrated the role of depressive disorders and cognitive impairment in the background of elevated mortality and decreasing QoL in old age [1‐4].

The close correlation between depression and dementia is well-known, however the link between them is still unclear, and a subject of intensive research. According to a recent meta-analysis, depression in old age can be an important risk factor for several types of dementia [5]. Furthermore, it was suggested that the same risk factors may be present in the background of dementia and depression in elderly, or even the same pathophysiological impairments may lead to both conditions [6‐8]. Based on these findings, depression may be an early marker of mild cognitive impairment and incipient dementia [9]. Furthermore, depression and cognitive impairments are also stressed as important risk factors for suicide in older adults [10].

Based on the above, we investigated depressive symptoms, cognitive functions and QoL of older people, and we also assessed the occurrence of the diagnosed and treated mental disorders and psychotropic medications. The primary goal of our study was to assess depressive and cognitive symptoms among older people in order to determine if those are recognized and effectively treated or not. We also aimed to better elucidate the association between depressive and cognitive symptoms and to investigate their impact on QoL. Based on the literature, our hypothesis was that in many cases cognitive decline and mood disorders are not recognized and treated, and these both negatively affect the QoL of older persons [11, 12].

In the framework of the ICT4Life project, self-administered questionnaires and clinical screening tools were used to assess QoL, depressive symptoms and cognitive functions of 60 older persons (47 females and l3 males) over the age of 65, who live independently in their own apartments and participate in the daily care facility programme for older people of the Integrated Social Institution in Pecs, Hungary [13]. Participation was voluntary and anonymous following the signature of the informed consent form (ICF). The study was conducted in 2017–2018, the data collection and medical record review lasted for 6 months. The questionnaires were administered by trained clinical psychologists, the clinical assessments and the medical record review were completed by psychiatrists. The study was approved by the local Ethics Committee.

Two tests were used to assess QoL of the participants, the abbreviated version of the Older People Quality of Life (OPQOL-Brief) and the Quality of Life in Alzheimer's Disease (QOL-AD) questionnaires. The former is a 13-item short version of the well-known QoL scale (OPQOL-35), which has beneficial psychometric properties [14]. The QOL-AD questionnaire was specifically developed to assess the QoL of people with dementia, especially Alzheimer’s disease. It is based on a semi-structured interview, in which 13 items regarding QoL are covered. Evaluation of the questions is based on a four-grade Likert scale ranging from bad to excellent [15]. The Mini-Mental State Examiner (MMSE) was used to evaluate the cognitive levels of the subjects. The total score is 30 points with a 24 points of cut-off score for dementia [16]. Depressive symptoms and the severity of depression was measured by the 15-item Geriatric Depression Scale (GDS) [17]. The short version of the GDS can be easily applied to patients even with mild or moderate cognitive decline as well; and is considered to be a useful tool to differentiate depressed older persons from the non-depressed ones [18].

We also assessed the socio-demographic characteristics, the physical and mental disorders, and medication usage with semi-structured interviews. The review of medical records was also completed in order to control data captured during the semi-structured interviews.

The data were analysed by using SPSS 20.0. We performed descriptive statistical analyses, χ²-probe and Mantel–Haenszel test were used to identify group differences, and ANOVA for comparison of mean values. The level of significance was set at p < 0.05.

About half of the subjects took some psychotropic medications, and the same proportion had cognitive impairment reaching the level of dementia (mainly mild, according to the MMSE), and a little less (but more than 40%) found to be depressed by the GDS depression screening tool (Table 1). Although it was somewhat more common to take antidepressant medications, there was a greater proportion of current depressive symptoms among males. No other major differences were found between genders.

Among the participants, out of the 11 patients taking antidepressants 6 patients were without current depressive symptoms, which may indicate the efficacy of the antidepressant treatment in old age (Table 2). 26 participants had current depressive symptoms, but only 9 of them contacted a psychiatrist, and 7 of them had a clinical diagnosis of depression. Furthermore, only 5 of them received antidepressant medication (which also means that 21 older adults were found to have depressive symptoms, but their depression was not treated), but still they had some depressive symptoms. On the other hand, these patients with current depressive symptoms were more likely to receive antipsychotic medications. This may indicate that only certain symptoms of the depressive disorder (sleep disturbance, anxiety, agitation) have been recognized and treated (with antipsychotics), while the underlying mood disorder was not considered, and therefore an adequate antidepressant treatment was lacking. Theoretically, antipsychotics, especially first-generation ones may be associated with the occurrence of depressive symptoms, but all the patients in the study population were treated with second-generation antipsychotics, which rarely induce depressive symptoms. Moreover, as it is known from the literature and clinical practice, some second-generation antipsychotics may improve depressive symptoms or can even work as antidepressants [19]. So, these antipsychotics might be prescribed to treat depression in older persons. Although for many patients there was only partial response to these antipsychotic or antidepressant medications, as—at least some of them—depressive symptoms were still present.

Based on our analysis, among older adults with current depression (according to the GDS) cognitive decline (assessed with the MMSE) was significantly more frequent and more pronounced, but this was not recognized and treated. In line with previous literature data, the results of this study showed that depressed (according to the GDS) older persons had lower cognitive levels and their QoL was also significantly poorer than that of the non-depressed. Our results also confirm close correlation between depression and cognitive impairment, as well as the key role of depression in the background of QoL decline [3, 20, 21]. On the other hand, it is well-known that reversible depression-related cognitive decline (also known as depressive pseudo-dementia) is often considered as true dementia and these patients do not receive adequate treatment for their mood disorder [22]. However, the depressive pseudo-dementia in old age seems to be a long-term predictor of true dementia [5, 23].

The common depressive symptoms in older adults contributes to poorer QoL and may also lead to the misdiagnosis of dementia. Our research also refers to the problems of recognition and effective treatment of depression in old age, which can be further complicated by the also common symptoms of cognitive impairment among depressive patients (depressive pseudo-dementia) [7, 24]. As depressive symptoms may be the first signs of dementia [6], early recognition of depression is important not only to treat the mood disorder, but also for the early detection and treatment of cognitive impairment [5]. The preventive significance of our results is evidenced by the fact that the screening, treatment and follow-up of depressed older patients is of high importance not only to adequately treat the mood disorder and avoid the misdiagnosis of depressive-pseudodementia as true dementia, but also to improve the QoL of the older persons. Furthermore, it may be beneficial to prevent further cognitive decline [9, 22] and other complications, such as increased cardiovascular morbidity/mortality and suicide [10, 25].