ABSTRACT The objective of this study is to investigate the clinical significance of a specific behavior of misplacing items in a refrigerator (i.e., placing extremely unusual things such as

remote control and/or cellular phone in a refrigerator) as a symptom of cognitive dysfunction. Patients with memory complaints were asked whether they ever experienced misplacing items in a

refrigerator, such as placing a remote control, a cellular phone, or other extremely unusual things inside a refrigerator (referred to as the ‘fridge sign’). Among the 2172 individuals with

memory complaints, 55 (2.5%) experienced symptoms of the ‘fridge sign’. We investigated the cognitive profiles of ‘fridge sign’-positive patients and performed follow-up evaluations with

the follow-up period. We compared the cognitive profiles and the clinical progression of 20 ‘fridge sign’-positive MCI patients and 40 ‘fridge sign’-negative MCI patients. ‘Fridge

sign’-positive MCI patients had worse scores on the Stroop test color reading and had higher scores on the geriatric depression scale than ‘fridge sign’-negative MCI patients, which

indicates that the ‘fridge sign’ could be indicative of selective attention deficit in patients with depression rather than indicative of cognitive decline related to dementia. SIMILAR

CONTENT BEING VIEWED BY OTHERS A HOUSEHOLD SURVEY OF THE PREVALENCE OF SUBJECTIVE COGNITIVE DECLINE AND MILD COGNITIVE IMPAIRMENT AMONG URBAN COMMUNITY-DWELLING ADULTS AGED 30 TO 65 Article

Open access 02 April 2024 FORGETTING IS COMPARABLE BETWEEN HEALTHY YOUNG AND OLD PEOPLE Article Open access 28 December 2024 SEQUENCE OF EPISODIC MEMORY-RELATED BEHAVIORAL AND BRAIN-IMAGING

ABNORMALITIES IN TYPE 2 DIABETES Article Open access 01 February 2025 INTRODUCTION As the prevalence of dementia increases in an aging society, there have been growing concerns about

dementia. When people visit memory clinics, clinicians interpret the severity of symptoms based on detailed history taking and cognitive function tests. People who visit the clinic with

concerns about memory impairment have some degree of experience with misbehavior or mistakes due to memory impairment. These symptoms include placing inappropriate things such as remote

controls and/or cellular phones in a refrigerator. Such a scenario has been portrayed in the media—TV drama and movies—as a symbolic behavior of Alzheimer’s disease or dementia. Even many

clinicians consider such behavior a ‘red flag sign’ associated with severe cognitive impairment. The fundamental question is whether these behaviors are truly a sign of dementia or of a

pre-dementia stage of a neurodegenerative disease. For example, memory decline and attention deficit are often not easy to distinguish and frequently coexist because maintaining appropriate

attention is a precondition for storing long-term information1,2. Attention deficit may make it difficult to perform memory tasks. In this study, we investigated the clinical significance of

the behavior of misplacing items in a refrigerator (i.e., placing a remote control, a cellular phone, or other extremely unusual things in a refrigerator, henceforth referred to as the

‘fridge sign’) as a symptom of cognitive dysfunction since many people who have had this experience are afraid that they may have dementia. RESULTS Among the 2172 subjects who visited our

clinic for the first time with memory complaints, 55 (2.5%) experienced symptoms of the ‘fridge sign’. The demographic findings of ‘fridge sign’-positive patients are shown in Table 1. The

‘fridge sign’-positive patients were composed of 33 with subjective cognitive decline (SCD, 60%), 20 with mild cognitive impairment (MCI, 36.4%) and 2 with dementia due to Alzheimer’s

disease (ADD, 3.5%). Among the subjects who never experienced symptoms of the ‘fridge sign’, 557 had SCD, 825 had MCI, 474 had ADD, and the remaining 261 had dementia of other etiologies

(vascular dementia, frontotemporal dementia, dementia of Lewy body, etc.). The proportions of SCD and MCI were significantly higher among the ‘fridge sign’-positive patients than among the

‘fridge sign’-negative patients. Forty-three of 55 ‘fridge sign’-positive patients underwent detailed neuropsychological tests. Thirty-three patients (76.74%) had high depression scores

according to the 30-item geriatric depression scale (GDepS) score (the cut-off value for a high depression score is > 10). There were no significant differences in demographic profiles

between the normal group and the group with high depression scores except age (Table 1). Among the 33 patients with high depression scores, 8 patients were on selective serotonin reuptake

inhibitors at initial presentation and 15 patients were not on medication. Of the patients with a positive fridge sign, 18 successfully completed the follow-up evaluation regarding their

cognitive status, including the neuropsychological test. The mean interval between the initial and follow-up tests was 20 months (range from 8 to 36 months). The patients who were

followed-up until the final evaluation were 6 SCD subjects, 11 MCI patients, and one ADD patient (Fig. 1). There was no case showing cognitive decline at the final follow-up evaluation

according to the detailed neuropsychological test. Four patients who were initially diagnosed with MCI were ultimately diagnosed with SCD since the final detailed neuropsychological test

showed an improvement in cognitive function. The diagnoses of the other 14 patients were not changed. One patient who was diagnosed with ADD with depression showed no disease progression

because the Mini-Mental Status Examination (MMSE) score changed from 19 to 20 in 1 year. Eighteen patients showed an improvement in the mean MMSE score, from 25.94 to 27.4. The clinical

dementia rating-sum of box (CDR-SOB) improved in three of 18 patients, while it remained the same in 15 patients (Fig. 2a). The mean GDepS score improved from 20.78 points to 14.8 points. Of

the 25 subjects who did not undergo the follow-up neuropsychological test, 16 subjects (64%) responded to the telephone interview. Twelve subjects (9 SCD subjects and 3 MCI patients) showed

no change in their cognitive function. Three subjects (one SCD subject and two MCI patients) showed improvement in their cognitive function. Only one subject initially diagnosed with SCD

showed cognitive decline after the initial evaluation. The mean Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) score of all patients was 3.02. We compared the ‘fridge

sign’-positive MCI patients (n = 20) with age-, sex- and education level-matched ‘fridge sign’-negative MCI patients (n = 40) (Table 2). The score of depression (_P_ < 0.001) and Stroop

test color reading (_P_ = 0.018) were significantly different between the two groups. ‘Fridge sign’-positive MCI patients had a worse score on the Stroop test color reading and had a higher

GDepS score (i.e., more depressive) than ‘fridge sign’-negative MCI patients. The distribution of the MMSE and GDepS scores between ‘fridge sign’-positive and ‘fridge sign’-negative MCI

patients is presented in Fig. 2b. There were no differences in the MMSE, CDR-SOB, or other detailed neuropsychological test results, including digit span, Boston Naming Test (BNT),

Rey–Osterrieth complex figure test (RCFT)-copy, phonemic controlled oral word association test (COWAT), verbal learning test (VLT) and trail making tests. Although statistically

insignificant, there were tendencies for the ‘fridge sign’-positive MCI patients to have worse scores in digit span forward/backward and VLT recognition scores. Among the included MCI

patients, 16 ‘fridge sign’-positive patients and 40 ‘fridge sign’-negative patients were undergoing follow-up evaluation either by detailed neuropsychological tests or structured telephone

interviews (Table 3). Seven patients among the ‘fridge sign’-negative patients progressed to dementia; in contrast, none of the ‘fridge sign’-positive patients showed progression of

cognitive decline. DISCUSSION People often think of the ‘fridge sign’ as a symptom of dementia and memory impairment, and even some physicians consider the symptom a representative red flag

for dementia. Contrary to common stereotypes, the ‘fridge sign’ is a relatively rare condition among individuals with memory complaints. In particular, the ‘fridge sign’ is mostly found in

individuals diagnosed with SCD or MCI and is relatively rare in dementia states. A conspicuous aspect of patients who visited our memory clinic with the ‘fridge sign’ was that they were more

depressive and inattentive subjects with or without cognitive impairment. According to the detailed neuropsychological test, there was a significant difference in the Stroop color reading

test score between the ‘fridge sign’-positive and ‘fridge sign’-negative patients. Depression scores were also significantly different between the two groups. Therefore, we can assume that

the ‘fridge sign’ is one of the signs indicating attention deficit due to depressive symptoms, whilst its presence does not exclude the presence of a pre-dementia or dementia syndrome. Over

the past decade, many studies have demonstrated a decrease in cognitive function in depressed patients3,4,5. To date, the affected cognitive domains in patients with depression have been

extensively identified as psychomotor speed6, short-term and explicit long-term memory7,8, and executive function, including attention9,10. The change in attention in depression is worth

noting because it is consistently confirmed to be reduced in depressed patients, acting as a gatekeeper of general cognitive function1. The Stroop test measures selective attention11,12,13

and depressed patients perform poorly on Stroop tests3,14. Overall, we can assume that patients with the ‘fridge sign’ may have decreased selective attention due to depression. There was no

statistically significant difference, but patients with the ‘fridge sign’ showed poor performance on the digit span forward and backward tests. These results also indicate that the

characteristic cognitive profile of patients with the ‘fridge sign’ is a decrease in selective attention. The symptom of putting inappropriate items inside the refrigerator may be

interpreted as a goal neglect response from interference in conflict situations, which is a symbolic expression of attention deficit associated with depressive mood, not with dementia or

other specific cognitive dysfunction, as it has been commonly misunderstood by the general public and some clinicians. The ‘fridge sign’ in depressive patients with attention deficit seems

to be explained as an automatic or habitual action, instead of purposeful work. According to our observations throughout the follow-up period of 2 years, patients with the ‘fridge sign’ did

not show progressive cognitive decline, according to the neuropsychological test or telephone interview; rather, they showed an improvement in both cognitive and functional status,

especially in patients with reduced depression scores after anti-depressant treatment. In a comparison of ‘fridge sign’-positive and ‘fridge sign’-negative MCI patients, 18.9% of the ‘fridge

sign’-negative patients progressed to dementia, while none of the ‘fridge sign’-positive patients progressed to dementia. Therefore, it can be said that the ‘fridge sign’ has little

relation to the progressive degenerative cognitive impairment. This study has potential limitations. First, this investigation was a single-center study, and a very small number of people

with memory complaints presented the ‘fridge sign’. Due to the low occurrence of the ‘fridge sign’, only a small number of subjects were included in subsequent analysis. In addition, the

‘fridge sign’ could only be measured by asking the subjects or their caregivers about their experience. So, there was a possibility of overrepresentation of SCD subjects reporting the

‘fridge sign’, whilst the patients with dementia could not report such symptoms due to their memory deficits, even though the investigation included the reports from caregivers or families.

Therefore, the results of this study are preliminary and need further investigation to validate the clinical significance of the ‘fridge sign’. Second, more than half of the patients with

the ‘fridge sign’ did not undergo the follow-up neuropsychological test. We conducted telephone interviews with a structured questionnaire to address this shortcoming. However, detailed

neuropsychological tests are essential to accurately understand the cognitive changes in patients with the ‘fridge sign’. Third, we defined and analyzed only the specific symptoms of putting

inappropriate items in the refrigerator, referring to the phenomenon of putting things in a very inappropriate place. Since women are more familiar with the refrigerator and other kitchen

equipment than men are, only female patients showed the ‘fridge sign’ in our study. For a better understanding of the phenomenon of the ‘fridge sign’ in both men and women, a different

definition of the ‘fridge sign’ will be needed. The fridge sign is a rare behavior among people who complain of cognitive decline, though it has a large impact on patients, caregivers, and

sometimes physicians. Through our study, we found that the ‘fridge sign’ is not a key feature of degenerative cognitive disease but rather a goal neglect response due to the selective

attention deficit influenced by depressive mood. If a person complains of the ‘fridge sign’ with cognitive decline, evaluating the patient’s attention function and measuring the degree of

depression would be important steps for the accurate diagnosis and treatment of cognitive dysfunction. METHODS PARTICIPANTS We collected data from subjects who visited the Neurocognitive

Behavior Center of Seoul National University Bundang Hospital with memory complaints between January 2011 and July 2017. At the initial visit, we asked all subjects and their caregivers

whether they ever experienced misplacing items in a refrigerator, such as placing a remote control, a cellular phone, or other extremely unusual things in a refrigerator. Detailed

neuropsychological tests were performed to identify the cognitive profiles. The diagnoses of the included subjects were determined by expert neurologists. The diagnosis of SCD was based on

the criteria proposed by Jessen et al.15, and the diagnosis of MCI was based on the criteria proposed by Peterson et al.16. ADD was diagnosed by the criteria proposed by the National

Institute on Aging and Alzheimer’s Association17. Moreover, we compared patients with ‘fridge sign’-positive MCI and those with ‘fridge sign’-negative MCI. ‘Fridge sign’-negative MCI

patients were defined as those who were matched in age, sex, and education level with the ‘fridge sign’-positive MCI patients who visited our clinic with memory complaints during the same

period and were diagnosed with MCI but without experience of the ‘fridge sign’. We excluded the data of people on medication with the anticholinergic effects and on benzodiazepines. The

protocol for the study was approved by the Institutional Review Board (IRB) of the Seoul National University Bundang Hospital and conformed to the provisions of the Declaration of Helsinki.

All subjects’ anonymity was preserved. Informed consent was waived for this retrospective study which was approved by the IRB of the Seoul National University Bundang Hospital.

NEUROPSYCHOLOGICAL ASSESSMENT We evaluated attention, language function, visuospatial function, verbal and visual memory, and frontal/executive function using a series of standardized

detailed neuropsychological tests. We collected the results of digit span test(forward and backward)18, Boston Naming Test (BNT)19, Rey–Osterrieth complex figure test (RCFT, copy)20, verbal

learning test (VLT)21 composed of free recall trials of 12 words, 20-min delayed recall task, recognition task, phonemic controlled oral word association test (COWAT)22, Stroop test23 (word

and color reading of 112 items within 2 min), and Trail making test part A and B24. The depression score was measured according to the self-reported 30-item geriatric depression scale

(GDepS)25. FOLLOW-UP EVALUATION We collected follow-up neuropsychological data from the included subjects. For individuals who had not undergone the follow-up neuropsychological test, we

conducted telephone interviews to assess changes in cognitive function. Cognitive changes were evaluated using the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE)26,27.

We used the cut-off value of ≥ 3.44 as the cognitive decline and below 3.00 as improvement of cognitive function after the initial IQCODE evaluation28. STATISTICAL ANALYSES The data were

analyzed using SPSS 20.0. The Mann–Whitney U test was used to compare age, education level, mini-mental state examination (MMSE)29, clinical dementia rating (CDR)30, CDR—sum of box

(CDR-SOB), GDepS, and all scores of neuropsychological tests between the ‘fridge sign’-positive and ‘fridge sign’-negative MCI groups. DATA AVAILABILITY The data supporting the findings of

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140, 566–572 (1982). Article  CAS  Google Scholar  Download references AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * Department of Neurology, Seoul National University Bundang Hospital, 82,

Gumi-ro 173, Beon-gil, Bundang-gu, Seongnam-si, Gyeonggi-do, 13620, Republic of Korea Jeewon Suh, So Young Park, Young Ho Park, Jung-Min Pyun, Na-young Ryoo, Min Ju Kang & SangYun Kim *

College of Medicine, Seoul National University, Seoul, Republic of Korea Jeewon Suh, Young Ho Park, Jung-Min Pyun & SangYun Kim Authors * Jeewon Suh View author publications You can also

search for this author inPubMed Google Scholar * So Young Park View author publications You can also search for this author inPubMed Google Scholar * Young Ho Park View author publications

You can also search for this author inPubMed Google Scholar * Jung-Min Pyun View author publications You can also search for this author inPubMed Google Scholar * Na-young Ryoo View author

publications You can also search for this author inPubMed Google Scholar * Min Ju Kang View author publications You can also search for this author inPubMed Google Scholar * SangYun Kim View

author publications You can also search for this author inPubMed Google Scholar CONTRIBUTIONS SY.K. conceived of the presented idea, developed the study design and provided scientific

guidance. J.S., S.Y.P, M.J.K and Y.H.P performed data collection. JM.P and N.R performed structural telephone interviews. J.S. performed data analysis and interpretation. J.S and S.Y.P wrote

the manuscript. All authors commented on the manuscript. CORRESPONDING AUTHOR Correspondence to SangYun Kim. ETHICS DECLARATIONS COMPETING INTERESTS The authors declare no competing

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Park, S.Y., Park, Y.H. _et al._ Misplacement of something inside the refrigerator is not a sign of dementia, but a probable symptom of attention deficit due to depression. _Sci Rep_ 11, 4978

(2021). https://doi.org/10.1038/s41598-021-84676-x Download citation * Received: 29 September 2020 * Accepted: 19 February 2021 * Published: 02 March 2021 * DOI:

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