With a growing global population, prevalence of dementia is increasing world-wide. It is estimated that approximately fifty percent of all residents in long-term care settings have dementia 12 and the resulting heterogeneity in behaviours of residents can challenge the demands on knowledge and skills of carers in residential care homes 345. Knowledge of dementia and Alzheimer’s disease (AD) has been shown to vary among caregivers in residential settings and among informal carers 67. Poor understanding of the impact of dementia on patient behaviour can result in suboptimal care-choices and can increase agitation or anxiety unnecessarily 8910. Reliable assessment of knowledge among carers is therefore paramount for patient well-being and for guiding decisions about training strategies by residential care homes or for development of training programs for informal carers 811.

A popular scale for assessing knowledge and misconceptions of Alzheimer’s disease is the Alzheimer’s Disease Knowledge Scale (ADKS 11). The ADKS consists of 30 ‘true/false’ statements related to seven ‘knowledge domains’: risk factors, symptoms, assessment and diagnosis, course of the disease, treatment and management, caregiving and life impact. So far, the questionnaire has been used to assess knowledge in the general population or among students (UK 12; Norway 13; USA 141516; South Korea17 among health professionals and care staff 18, among psychologists 19 and it has been used as an outcome measure for validation of an online training program for care-workers 20.

One potential limitation of the ADKS is that ‘true/false’ responses in knowledge questionnaires provide only limited information about the reasons why an incorrect response is given 21222324. As suggested by Courtenay and Weidemann 21, true-false statements fail to distinguish between true misconceptions (incorrect responses) and lack of knowledge (‘don’t know’) about a given topic. The aim of the present study is to investigate whether addition of a ‘don’t know’ option would allow a more reliable separation between misconceptions and self-reported knowledge gaps in a sample of the general population and carers of people with dementia (care home carers of elderly residents and informal home carers). This separation is particularly relevant for responses of carers as different answers could be associated with different care choices. For instance, selection of the incorrect answer when ‘don’t know’ is available suggests that the answer is given with confidence and could result in suboptimal caregiving responses, whereas selection of ‘don’t know’ suggests admission of a knowledge gap and is more likely associated with information seeking. In addition, inclusion of the ‘don’t know’ response could provide an index of genuine knowledge that is not inflated by guesses when only ‘true’ and ‘false’ are the available response options.

A total of 228 participants took part in the study, of which 51 were men and 173 were women (4 participants did not disclose their sex). One hundred and eighteen participants were recruited from care homes, 20 participants cared for people with Alzheimer’s disease at home, and an opportunity sample of 80 people were recruited from the general population and university staff and students. Care home workers were recruited from residential care homes for the elderly via a local care trust responsible for 15 care homes in Lincolnshire. Job roles of care home workers were as follows: Caregiving (63.6%), kitchen staff (16.1%) housekeeping (15.3%) and other (5.1%). Informal caregivers were recruited via meetings organized by the Alzheimer’s disease society for patients with Alzheimer’s disease living at home.

The ADKS (Carpenter et al, 2009) assesses knowledge about seven knowledge domains: risk factors (e.g., ‘Genes can only partially account for the development of AD’), symptoms (e.g., ‘Most people with AD remember recent events better than things that happened in the past’), assessment and diagnosis (e.g., ‘AD is one type of dementia’), caregiving (e.g., ‘People with AD do best with simple instructions, given one step at a time’), treatment and management (e.g., ‘AD cannot be cured’), life impact (e.g., ‘It is safe for people with AD to drive, as long as they have a companion in the car at all times’) and course of the disease (e.g., In rare cases, people have recovered from AD’). The original ADKS was modified for the purpose of this study by adding a third response option (‘I don’t know’) to the two original response options (‘True’ or ‘False’) for each statement.

In addition to the ADKS statements, the questionnaire included questions about education and specific dementia training. Education was rated on a 6 point scale: 1=’left school before 15’, 2=GCSE, 3=A-level, 4=Diploma, 5=1^st degree, 6=higher degree. Specific dementia training was categorized as follows: ‘Tertiary training’ (undergraduate or post-graduate course include specific AD course content); ‘Dementia training’ (dementia specific conferences, in-service dementia course or workshop; ‘Other dementia learning’ (self-directed learning (e.g. on-line); ‘No training at all’. Three additional questions were asked about their level of experience with AD: Question 1 (E-Q1): ‘Do you personally know anyone who has had Alzheimer’s disease (or a related disorder’); Question 2 (E-Q2): ‘Are you currently, or have you previously been a caregiver to a family/friend with Alzheimer’s disease (or a related disorder)’; Question 3 (E-Q3): Do you have any experience of working with people who have Alzheimer’s disease (or a related disorder)’. These three questions required either a ‘yes’ or ‘no’ response. Participants were also asked to rate their own knowledge of Alzheimer’s disease on a 10-point Likert scale (where 1= I know nothing at all and 10= I am very knowledgeable).

The present study used a modified version of the ADKS to assess knowledge about AD among carers and in a sample of the general population. Inclusion of the ‘don’t know’ option (selected ~23% of the time) reduced both correct responses (-10%) and incorrect responses (-11%) in the sample from the general population compared to percentages reported in our previous study 12 suggesting that percentage correct responses may be a better index of true knowledge about AD when the ‘don’t know’ option is included. Furthermore, consistent with findings of previous studies using true/false/don’t statements to investigate knowledge about effects of ageing on memory 2122 the ‘don’t know’ option distinguished between real knowledge, misconceptions and self-reported knowledge gaps. Care home carers, informal carers and other professionals with dementia-experience at work all obtained a higher percentage correct response compared to those who had no experience with dementia, whereas only care home carers selected the incorrect answer more often than the other two groups for the knowledge domain ‘course of the disease’. Conversely, only care home carers selected ‘don’t know’ significantly less often for this knowledge domain compared to group four. Combined, these results seem to suggest that the carers who work in care homes had a relatively high level of misconceptions about the course of Alzheimer’s disease. One possible explanation that may require consideration for the interpretation of this result is that responses of carers may have been influenced by a systematic responses bias 25. Specifically, care home carers may have felt that they should know the answers to all ADKS items given their profession and as a result may have avoided the ‘don’t know’ option. Whilst not implausible, the anonymous completion and treatment of all questionnaires should have eliminated any potential external pressures that could have resulted in avoidance of don’t know response. Moreover, if care home carers adopted this general strategy, then higher percentages of don’t know responses for care home carers would be expected compared to all other groups, not just compared to group 4. Nevertheless, future studies will be required to address potential influences of response biases in care home carers, for example by allowing further elaboration on individual answers in focus groups following completion of the ADKS.

The tendency of care home carers to select the wrong answer instead of don’t know was particularly pronounced for four ADKS items associated with relatively low accuracy overall. Two of these items concerned statements about the course of the disease (Q17“Eventually a person with Alzheimer’s disease will need 24 hour supervision” and Q14: “A person with Alzheimer’s disease becomes increasingly likely to fall down as the disease gets worse”), one question concerned knowledge of symptoms (Q22: Trouble handling money or paying bills is a common early symptom of Alzheimer’s disease) and one question was related to treatment and management (Q7: If a person with Alzheimer’s disease becomes alert and agitated at night, a good strategy is to try to make sure that the person gets plenty of physical activity during the day). The fact that care home workers selected the incorrect response for these questions is surprising as they describe situations that carers could be assumed to be familiar with. Whilst these results indicate true misconceptions, a few alternative possible explanations should be considered. One such explanation is unintended incorrect interpretation of some of the items. For example, even when living under supervision in residential care 24 hours per day, patients with AD may not need ‘eyes-on’ supervision at all times of the day. Alternatively, responders may have relied too heavily on their observations at work for some of the items. For example, although statements 14, 17 and 22 may be familiar to those who have followed the progression of the disease closely (such as informal carers), care home carers are more likely to meet their residents when dementia has already progressed to later stages of the disease. Care home carers may therefore not necessarily have observed the gradual increase in falls or the first few times that residents experienced difficulties with handling money. Whilst speculative, this interpretation seems to be supported by the high percentage of correct responses for these four questions by informal carers. It will require further research with a larger sample, particularly of informal carers, to investigate the potential influence of item interpretation and the type of experience professionals have with dementia on their ADKS answers.

Consistent with our previous findings 12, knowledge about risk factors related to life-style (hypertension, cholesterol) were only answered correctly by a very small percentage of participants (~20%) and were associated with a high percentage of incorrect responses (~38%). Frequency distributions were comparable for the four groups suggesting that misconceptions about this topic were similar for carers and non-carers alike. These findings seem to suggest that scientific advances on the relationship between cholesterol, hypertension and AD 26, including new insights into the potential positive effect of statins in treatment plans 2728 are not effectively communicated to informal carers, care home workers and the general population. Given that both our studies were conducted in the UK implies little awareness about these factors in the British population, despite ongoing national dementia awareness campaigns 2930.

A few results were consistent with previous findings 189 (Smyth et al, 2013; Robinson et al, 2014). Specialist dementia training was associated with higher total percentages of correct ADKS responses, confirming existing evidence for the beneficial effects of specialist training on knowledge of dementia 31. Higher ADKS responses were also associated with those who rated their own knowledge higher, replicating our previous findings and those obtained from Australian health professionals 1218. Conversely, a few correlations may have been unique to the sample used in the current study and require further consideration. Table 3 shows that age of the participant correlated positively with ADKS score, negatively with education and positively with self-reported knowledge. This pattern of correlations is likely due to differences between groups in terms of age (reducing from Group 1 to 4) and level of education (increasing from Group 1 to 4) (see Table 1), which could be explained by the relatively high proportion of university students in this group (N=26) compared Group 3 (N=6) and Groups 1 or 2 (none). Although multivariate regression analysis would have been informative for exploring the predictive value of group membership (Group 1-4), age, education and self-reported knowledge, multicollinearity can be problematic for interpretation of regression models 32. Future studies investigating knowledge of AD in carers may consider matching the control group more carefully with the carers in terms of age and education.

The present study demonstrates that inclusion of the ‘don’t know option in the ADKS provides valuable insight into the reasons why respondents select incorrect responses (misconceptions versus knowledge gaps). The study revealed that care-home carers were more likely to select the incorrect response with confidence for several items, suggesting a higher level of misconceptions than for informal carers. Possible item-specific explanations were considered, highlighting training needs for improving knowledge of care home workers about the impact of AD on behaviour at earlier stages of the disease.