Lethologica in aging: An analytical study

PC Girija; N P Fathima Shahal; Nayana Narayanan

doi:10.4103/jiag.jiag_32_21

ORIGINAL ARTICLE

Year : 2022 | Volume : 18 | Issue : 1 | Page : 9-14

Lethologica in aging: An analytical study

PC Girija, N P Fathima Shahal, Nayana Narayanan
Department of Audiology and Speech Language Pathology, AWH Special College, Kozhikode, Kerala, India

Date of Submission	30-Nov-2021
Date of Decision	14-Dec-2021
Date of Acceptance	23-Feb-2022
Date of Web Publication	21-Apr-2022

Correspondence Address:
Dr. P C Girija
AWH Special College, Kerala University of Health Sciences, Kozhikode - 673 003, Kerala
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jiag.jiag_32_21

Abstract

Introduction: Lethologica is a phenomenon that is an early sign of aging. Lethologica refers to the inability to retrieve a specific word as a response to a visual, auditory, or tactile presentation. Need: Even though it is known that aging has a strong impact on cognitive language functions, it is not yet clear which aspect is most affected. Since naming is an important element of language functions, analysis of this aspect would aid in understanding the nature of deterioration of cognitive‒linguistic functions with age. Aim: The aim is to analyze the impact of aging on naming abilities in neurotypical individuals. Methods: One hundred and fifty neurotypical individuals of 30 individuals from each group between 30 and 80 years of age, i.e., 31–40 years, 41–50 years, 51–60 years, 61–70 years, and 71–80 years participated in the study. A tool was developed in Malayalam language to assess confrontation naming, responsive naming, generative naming, and contextual naming. A score of 1 was given for each correct response. Results: As age advances, all the naming abilities deteriorated. The effect was most prominent in the generative naming task as it demands the most cognitive involvement. The neuronal areas governing these cognitive aspects mainly include the prefrontal cortical regions which are highly susceptible to the aging process. Responsive naming and contextual naming were least affected as it gained the advantage of crystallized intelligence. The age-related decline is more prominent after the age of 60 years. Conclusion: Naming skills, even though being a language element also have strong foundations within the cognitive domain. Hence, any age-related neurobiological alterations can impact naming functions.

Keywords: Aging, cognition, lethologica, naming

How to cite this article:
Girija P C, Shahal N P, Narayanan N. Lethologica in aging: An analytical study. J Indian Acad Geriatr 2022;18:9-14

How to cite this URL:
Girija P C, Shahal N P, Narayanan N. Lethologica in aging: An analytical study. J Indian Acad Geriatr [serial online] 2022 [cited 2023 Mar 21];18:9-14. Available from: http://www.jiag.com/text.asp?2022/18/1/9/343683

Introduction

The term “lethologica” refers to the inability to remember a particular word or name. Naming is an aspect of everyday taxonomy as people distinguish the objects of their experience, together with their similarities and differences. It is one of the most important abilities in linguistic processing. The task requires retrieval of phonological and semantic information, which is organized in a memory system and assessed depending on the specificities of a given stimulus. Naming involves lexical and nonlexical processing. The former refers to the storage and retrieval of semantic information and abstract representations connected with a particular word, whereas the latter involves the detection and perception of the visual stimuli that trigger the lexical process. Naming is a skill that is learned early and refined throughout adulthood and this skill is variously referred to as word finding, word retrieval, lexical retrieval, etc.,^[1] word-finding difficulty or naming difficulty interrupts the flow of conversation and can discourage the desire to communicate.

There are different types of naming such as confrontation naming, generative naming, responsive naming, and contextual naming.

Naming is mainly associated with left prefrontal,^[2],[3],[4] left precentral area, left Broca's area,^[5] inferior parietal, and left middle inferior temporal regions,^{[5],[6],[7],[8],[9]} apart from this, many authors have reported the influence of subcortical structures in the naming process.^[10],[11]

The naming process involves the activation of multiple processes involving speech, language, and cognition. It is well known that the rudimentary processes involved in naming can be summarized into “recognition, access, and retrieval.” Many models have explained these processes in various forms. According to Race and Hillis,^[12] naming can be simplified as two broad processes, namely conceptual and word form processing. Conceptual stage entails the semantic representation of the stimulus, whereas word processing links semantic representation to phonological representation without any modality influence. During name generation, there is an active involvement of motor speech musculature for the execution of the target utterance. Most of these models have failed to explain the neuronal basis of activation during naming. Recently, Duffau et al.^[13] have designed a hodotopical model of picture naming using brain stimulation mapping in which they identified the neural substrates for the naming process. According to this model, the initial process involved is visual word recognition evidenced by activation in the visual cortex as well as the parieto-inferior temporal areas for visual word form recognition. The activation proceeds to temporal pole and orbitofrontal areas for naming without conceptualization, whereas there is an active involvement of the dorsolateral prefrontal cortex, frontal operculum, supramarginal, and angular gyrus for syntactic and semantic processing during naming. Furthermore, activation was noted in the caudate nucleus for executive functions. Thereafter, activation proceeds to the primary and secondary motor cortices for the execution of motor commands involved during naming.

Older individuals frequently have alteration in their naming ability. The names, very well learned and frequently used at a younger age, are more difficult to retrieve as one grows older. Older subjects were significantly slower than younger individuals in producing the name of an object. This can be noted if the stimulus is either a picture of the object or a verbal description of it. Older individuals are also less accurate than younger subjects in naming an object when it has been described. Word finding difficulties in healthy aging may result either from a deterioration of frontal neural substrates that underlie the ability to access and retrieve appropriate lexical word forms or from a deterioration of the semantic stores that represent meaning, thought to reside, at least in part, in the inferior temporal lobe.^[14] Maylor^[15] suggested word retrieval performance in confrontation naming tasks is better even in older individuals because certain types of memory abilities such as vocabulary remain intact with increasing age. Tsang and Lee^[16] reported that younger people performed much better than older people on the confrontation naming test in terms of accuracy as well as response latency. According to Goulet et al.,^[17] declines in general cognitive ability seen in older individuals can lead to poor performance on confrontation naming. Age-related increases were also found in the use of indefinite terms, vague references, and circumlocutions when participants were naming a picture.^[18] Evrard^[19] has indicated that retrieval of proper names (people or places) is disproportionately affected by advanced age compared to common names (objects).

One of the significant challenges faced by older individuals is their inability to name objects, persons, places, etc., with the demands of the situation. This may significantly impact their confidence in using speech and language, especially in adverse situations (ex-speaking in an unfamiliar environment). By analyzing the naming abilities in older individuals, we will be able to gather information regarding the nature of their deficits, which in turn would equip older individuals to deal with their naming afflictions.

Aim

The aim is to analyze the impact of aging on naming abilities in neurotypical individuals.

Methods

The study was carried out in three phases:

Phase 1-Development of assessment material
Phase 2-Test administration
Phase 3-Scoring and statistical analysis of the data.

The primary aim was to develop a material in Malayalam to assess the naming abilities in adults. This was based on a detailed review of literature, including information from Western Aphasia Battery.^[20] The developed material contains different naming categories that are confrontational, generative, responsive, and contextual naming. The material contains 50 pictures (10 animals, 10 body parts, 10 common objects, 10 colors, and 10 action verbs) to assess confrontation naming, category fluency, and letter fluency to assess generative naming, 20 verbal description samples were used to assess responsive naming, 20 unfilled sentence sample to assess contextual naming. A pilot study was carried out for selecting the words.

Confrontation naming

Involves the selection of a specific label corresponding to a viewed picture of an object or action.

Seventy pictures were sampled and a pilot study was carried out to analyze responses on ten neurotypical adults from each group to check the appropriateness of the material. It was found that fifty selected items could elicit naming skills.

Instruction

I will be presenting you with 50 color pictures of 10 animals, 10 body parts, 10 action verbs, 10 colors, and 10 common objects and all you have to do is to name the pictures correctly within 60 s.

Scoring

Score of 1 will be given for each correct response and score of 0 is given for each incorrect response.

Generative naming or divergent naming ‒ It is the ability to fluently list members of a category in which participants have to produce as many words as possible from a category in a given time within 60 s. It includes a combination of letter fluency tasks and categorical naming tasks.

A pilot study was carried out on ten neurotypical adults from each age group to check the appropriateness of the material. It was found that selected items could elicit the naming skills.

Instruction: Here, there are two tasks. For the first task, I will be giving 1 min time period to name as many animals as you can. For the second task, you must name words starting with letter/a/,/f/,/s/in Malayalam.

Scoring

Score of 1 will be given for each correct response and score of 0 is given for each incorrect response.

Responsive naming

It is the ability of an individual to respond to characteristics of the object.

Forty descriptions about a particular lexical category were sampled for each object to be named and a pilot study was carried out on ten neurotypical adults from each age group to check the appropriateness of the material. It was found that twenty selected items could elicit the naming of the respective target precisely.

Instruction

I will be giving you a description about particular items; listen to the description and name it.

Score of 1 will be given for each correct response and a score of 0 is given for each incorrect response.

Contextual naming is defined as an individual's ability to interpret the part of a written or spoken statement that precedes or follows a specific word or passage, usually influencing its meaning or effect.

Forty unfilled sentences were sampled for each item to be named. A pilot study was carried out on ten neurotypical adults from each age group to check the appropriateness of the material. It was found that twenty selected items could elicit the naming of the intended item accurately.

Instruction: I will be presenting incomplete sentences; you have to fill in the correct responses, for example, ice is…………(cold).

Scoring

Score of 1 will be given for each correct response and score of 0 is given for each incorrect response.

Participants

A total of 150 participants within the age range of 30–80 years were selected for the study. They were grouped into 31–40 years, 41–50 years, 51–60 years, 61–70 years, and 71–80 years.

Inclusion criteria

The participant should not have any history of speech language, neurological, or psychological problems
The participant should have Malayalam as their mother tongue
The participants should have an education of at least 10^th standard and should know to read and write Malayalam. The participant should have normal/corrected vision and hearing.

All the participants were screened using Addenbrooke's Cognitive Examination in Malayalam^[21] to rule out the presence of dementia components.

Test administration

The administration of the test was begun by obtaining formal consent from the participants and caretakers. The participants were informed about the purpose and nature of the assessment prior to testing. Informal screening was done to check for the presence of hearing loss.

General case history regarding the patient was taken initially. To rule out the presence of aphasia, Western Aphasia Battery in Malayalam^[22] was administered. The participants were seated in a quiet and comfortable room. The clinician initially made rapport and appropriately instructed the participant before the administration of the test.

Scoring

Scoring was done according to the response to each stimulus. Correct and incorrect responses were considered for analysis. Types of errors were recorded using HUAWEI Y9 model JKM-LX1.

Results

Statistical analysis was done to determine the impact of aging on naming abilities. [Table 1] and [Figure 1] shows the overall mean and standard deviation scores for all of the naming categories.

Table 1: Results of ANOVA scores between the age groups and within each age group

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Figure 1: Overall and standard deviation scores of naming categories. The overall mean standard for each naming task summed across various age groups is revealed in the figure. The red bars depict standard deviations

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The results reveal that participants obtained maximum scores were obtained for responsive naming followed by contextual naming and confrontational naming. The least scores were obtained for the letter fluency task, whereas the scores obtained for generative naming and categorical naming were comparatively better than the letter fluency task.

[Table 1] and [Figure 2] represents the results of analysis of variance (ANOVA) scores between the age groups and within each age group.

Figure 2: Naming tasks across age groups. The trend of each naming tasks as portrayed by individual graphs for all the age groups. Blue portion represents mean and red portion represents standard deviation, (a) represents trend in confrontation naming with age, (b) represents trends in categorical naming with age, (c) represents trends in letter fluency with age, (d) represents trends in generative naming with age, (e) represents trends in responsive naming with age, and (f) represents trends in contextual naming with age

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ANOVA results displayed that there exists a significant difference between the age groups as well as within each age group. That is the hierarchical order of affected naming categories significantly remains constant throughout all age groups.

[Table 2] shows the mean and standard deviation of each naming category across the age groups.

From [Table 2], it is evident that responsive naming is the least affected domain even as age progresses followed closely by contextual and confrontation naming. As age progresses, the standard deviation also increases until it reaches stagnation at 71–80 years.

Table 2: Mean and standard deviation scores of each naming category with advancing age

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[Figure 2] depicts the trend of each naming category with progressing age. It is evident from the figure that naming abilities, irrespective of their nature, tend to decline as age advances. Confrontation naming, responsive naming [Figure 2] and contextual naming show gradual decline till the age of 60 years followed by a sudden plummet in performance. Generative naming [Figure 2], which was obtained by averaging scores of letter fluency and categorical naming, tends to significantly cascade down with each advancing decade. Letter fluency [Figure 2] is the most affected domain right from the age of 30 years. It further plunges down remarkably after the age of 60 years.

Discussion

From the above analysis, it can be substantiated that lethologica is a predictable phenomenon of aging. The explanation for this can be found within the constraints of age-related deterioration in cognitive linguistic abilities due to generalized cerebral atrophic changes. These changes can devastate the ability to activate working memory, conceptual utilization, and efficient exploitation of the lexico-semantic system even in a healthy aging population, thereby leading to lethologica.

Even though lethologica is an expected fact of aging, the nature of this deterioration needs to be analyzed, which was the pivotal point in our study. From the selected domains of naming, it was evident that letter fluency thrived poorly, whereas best scores were obtained for responsive naming, contextual naming, and confrontation naming. The letter fluency task requires extensive activation of interconnected networks for phonological retrieval. The strategy used for the letter fluency task employs search based solely on lexical representation and active suppression of semantic memory. This process is primarily governed by the left dorsolateral prefrontal cortex.^[23] Older individuals have less ability to actively utilize this area for phonological retrieval functions, which is portrayed in poorer performance in the letter fluency tasks.

Categorical naming scores were better as the task exploited the semantic system, which is found to be relatively well preserved^[24],[25] even in older adults. Literature reports that the brain regions activated during the process of categorical naming includes lateral fusiform gyrus, right superior temporal sulcus, medial fusiform gyrus, left middle temporal gyrus/inferior temporal sulcus, left ventral premotor cortex,^[26] and also anterior temporal lobe, posterior temporal, and posterior inferior parietal lobes, with prominent involvement of the left inferior fronto-occipital fasciculus and uncinate fasciculus fiber pathways.^[27] During the categorical naming task, many areas are activated at once, including the modality-specific activation and general amodal activation. Hence, it can be said that semantic activation taps the overall involvement of the cortex. Hence, a compromise in functions of one area may be compensated by other multiple areas. Adding onto this, the fact is that semantic memory is continuously activated owing to its greater demand, which can stabilize the whole system.

Generative naming scores were poorer as it combined scores of letter fluency and categorical naming. Even though categorical naming showed good scores, the poor scores of letter fluency contributed to the subpar scores of generative naming.

Confrontation naming showed poorer scores compared to contextual and responsive naming. Confrontation naming involves lexical access, which occurs through the activation of the occipital lobe (visual areas), posterior inferior temporal area where visual object recognition takes place. This is directly connected to the temporal pole and angular gyrus and finally to the orbitofrontal area of the dorsolateral prefrontal cortex. These areas undergo significant atrophic changes during aging, thereby affecting the confrontation naming.

Participants obtained better scores in responsive naming and contextual naming as this task does not demand many resources from cognitive linguistic faculties rather employs long-term memory for its completion. As long-term memory is relatively preserved in healthy aging populations, their responses also are better. As the task gains the advantage of familiarity and provides semantic cues, it reduces the load on cognition, thereby reducing the effort. Furthermore, multiple areas from different cortical regions are simultaneously, thereby nullifying the effects of neurobiological changes in one particular area related to aging. Hence, all these reasons can be attributed to better performance of the participants.

Summary and Conclusion

Naming involves the recognition of object to be named thereafter retrieving the correct name. Lethologica is the phenomenon observed when an individual is unable to retrieve the name. This is especially evident as age advances. Our findings reveal that after the age of 60 years, there is an evident increase in lethologica, especially for the naming tasks, which load the cognition and working memory more than the others. That is the reason why generative naming which involves the individual to recruit working memory to a great extent showed steep decline, whereas the naming tasks that use long-term semantic memory showed more stability with increasing age. This proves that cognition is a crucial element even in language-oriented tasks like naming. With an increase in task complexity for linguistic naming tasks, it demands more strain over cognition and demands greater involvement of resources. In aging, the prefrontal cortices are highly susceptible to neurobiological changes related to aging, thereby resulting in lethologica.

Ethical statement

The study was approved by the ethical committee of AWH Special College. The data were obtained with informed consent from all the participants involved and is the original work of the authors. Further, it is not submitted elsewhere and reflects the authors' own research and analysis in a truthful and complete manner.

Financial support and sponsorship

Nil

Conflicts of interest

There are no conflicts of interest.

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