Table 1

Relationship between laughter/smiling and the progression of dementia

Type of laughter/smile

Preservation in dementia

Early stages

Advanced stages


A1. Release from strong tension

+

+

A2. Release from weak tension

+

+

B1. Fulfillment of instinctive needs

+

+

B2. Fulfillment of expectations

+

-

B3. Feelings of superiority

+

-

B4. Feelings of disharmony

+/-

-

C1. Cooperative

-

-

C2. Defensive

-

-

C3. Aggressive

-

-

C4. Devaluating

-

-


The type of laughter and/or smiling can be classified into one of three categories: (A1,2) that evoked by a release of tension; (B1-4) that associated with pleasant feelings; and (C1-4) that used for social communication. Laughter and smiling induced by a release of tension is regarded as the most basic type and is preserved as the phylogenetically primitive type. Laughter and smiling associated with pleasant feelings has developed with the evolution of humans. Laughter and smiling as communication tools are the most sophisticated and have developed with the sociability of humans. Dementia patients lose the ability to laugh and smile as the disease progresses. Laughter and smiling as communication tools may be lost in the early stages of dementia, when the clinical symptoms of dementia appear. Of the different forms of laughter and smiling associated with pleasant feelings, those induced by disharmony may be lost in early stages of dementia because of the cognitive impairment that may limit a patient's understanding. However, laughter and smiling induced by feelings of superiority, fulfillment of expectations, and fulfillment of instinctive needs are preserved until the advanced stages of dementia. Laughter and smiling in response to a release of tension are preserved in most dementia patients.

Takeda et al. BMC Complementary and Alternative Medicine 2010 10:28   doi:10.1186/1472-6882-10-28

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