The beginning of the COVID-19 pandemic marked a radical change in people’s lives, becoming a real threat to public health worldwide.

Many of the preventive measures adopted in different countries had among their main priorities protecting older people due to the severity of the manifestation of the disease and the high morbidity and mortality rates in this population ^[1][2][3][1,2,3]. This situation can be expressed in the mortality rate increase among the population over 60 years of age, which was described to be up to 5 times higher than in other age groups [4].

Inevitably the pandemic and its containment measures had a relevant impact on the sociocultural, economic, and psychological spheres ^{[5][6][7][8][9]}[5,6,7,8,9]. The prevention and mitigation of the disease itself have been the main focus of attention. Despite this, the minimisation of the negative consequences of isolation at the psychosocial level has often been in the background. In many countries, the public health policies adopted different measures, such as home lockdowns and closures of social gathering places [10]. In older people, social isolation is especially relevant due to the possible decrease in different functional aspects of the person and an increase in the difficulty in carrying out daily activities [11]. The consequences on mental health have been widely studied by many authors, who have described how the context of COVID-19 can affect the geriatric population’s mental state with disorders such as depression, anxiety, stress or insomnia ^{[5][6][12][13][14][15][16]}[5,6,12,13,14,15,16]. According to previous research, the prevalence of depression in older adults showed a significant increase from 7.2% to 19.8% since the beginning of the pandemic [17] and psychogeriatric admissions increased by more than 21% [18]. The factors associated with different psychological conditions during the pandemic were investigated in a meta-analysis by Wang et al. [6], which focused predominantly on the general population and reported that female gender, being aged <35, lower socio-economic status, higher risk of COVID-19 infection and longer media exposure were associated with psychological distress. The risk and protective factors of depression in older adults were described in a recent systematic review, which more homogeneously identified impairment, sleep disorders and chronic diseases as main risk factors, and physical activity as a protective factor; however, this review was not focused on the period of the COVID-19 pandemic, as the included studies were published between January 2000 and March 2020 [19]. To the best of our knowledge, no systematic reviews have been published to analyse the factors associated with depression and anxiety in the aged population during COVID-19. The identification and understanding of these factors represent a relevant aspect of minimising the impact on the psychosocial sphere of the adverse effects that the preventive and containment measures adopted during the pandemic may produce.

Regarding age, despite being the group of individuals most at risk of suffering from a severe form of the disease ^[1][4][1,4], and in contrast to our initial hypothesis, the results found in this review indicate that being older is a protective factor for depression or anxiety ^[20][21][21,23]. It is important to note that, among the studies that analysed age as a predictor, three recruited their sample directly from older people ^[20][21][25][21,23,30], one selected long-term care home residents with a mean age of 81.4 (±11.5) years ^[23][28], and in one most of the participants were in the age range of 70–79 years (mean age 72.3 ± 10.9) ^[22][27]. Consequently, it must be considered that the comparisons between ages when calculating the OR were made within a relatively similar range. This may have led to obtaining less significant odds than comparing age groups with a greater difference. The results of a review carried out in the general population during the period of COVID-19 were in line with our data, and reported that younger ages presented a higher OR for both depression and anxiety [6].

By comparison, pre-pandemic studies analysing the relationship between age and mental health outcomes associate the presence of depression and anxiety with the advance in age, with a prevalence among the older population ranging between 3% and 15% for anxiety and up to 42% for depression ^[28][33][35,40]. A possible explanation for this difference may be that, in the context of COVID-19, multiple control measures involved social restrictions and reduction of working activity in many areas. Younger people may have been more affected by such a radical lifestyle change. They may experience greater fear regarding their occupational and economic future than a population already retired or close to the retirement age and whose daily routine may have been affected in a minor way.

Different physical conditions presented a greater number of significant associations with anxiety, suggesting that flu symptoms ^[34][24], severe physical illnesses ^[35][26] and having more than 14 days with COVID-19 symptoms ^[20][21] may represent possible risk factors. Mental health factors have several significant associations. However, whether these factors are associated with positive or negative outcomes may change according to the study: three studies identified the presence of current cognitive disorders as risk factors for depression and anxiety ^[20][34][26][21,24,31], whereas two others reported that the presence of different psychiatric diagnoses represented protective factors for depression ^[35][23][26,28] and comorbid depression and anxiety ^[35][26]. It is interesting to note that the data collected in most of these studies was self-reported through surveys, although it was not clearly stated how the presence/absence of pathology was defined, and data was not collected via a clinical examination by a professional; these factors may lead to differences in the results. The factors in the health sphere that were more consistently associated with both depression and anxiety among the studies were those related to the presence of low quality of sleep ^[36][21][35][22,23,26], and psychophysical comorbidity was among the most prevalent of the COVID-19 era ^[37][41].

Living or feeling alone are associated with both depression and anxiety ^[21][34][23,24]. Indeed, people’s social sphere has been one of the most affected by COVID-19 [9]. Containment measures, together with public health policies, resulted in a drastic reduction in social life, which could nearly be eradicated in the case of a home lockdown. It may be expected that in a context where a large degree of the development of social relationships occurs within the household, living alone, without a partner or with bad relationships with partners may predispose individuals to the development of depressive symptoms or anxiety. However, these considerations about social relationships may not extend to contacts via technology. One study included in our review shows that levels of social media contacts did not significantly alter the risk of reporting worsening depression and that their relationship with anxiety was unclear ^[21][23].

Exercising may represent a protective factor against it ^[36][22]. Previous research associated depression with aspects related to a lower motor function, such as less grip strength ^[38][43] or a slower gait speed ^[39][44]. The relationship of poorer function, disability and depression is often described as bidirectional, with the possibility that both factors influence each other ^[39][44].