The anorexia of ageing

Area of Science:

• Gerontology
• Nutritional Science
• Neuroscience

Background:

• Ageing is linked to reduced appetite and weight loss, known as the 'anorexia of ageing'.
• This physiological anorexia can lead to pathological weight loss, malnutrition, and increased mortality in older adults.
• The underlying causes of age-related appetite reduction remain largely unknown.

Purpose of the Study:

• To investigate the physiological mechanisms contributing to the anorexia of ageing.
• To explore the roles of endogenous opioids and cholecystokinin (CCK) in age-related changes in appetite.
• To identify potential therapeutic targets for combating malnutrition in the elderly.

Main Methods:

• Administered intravenous naloxone (opioid antagonist) to young and older adults to assess feeding drive.
• Infused cholecystokinin-8 (CCK-8) intravenously into participants to measure its satiating effects.
• Compared food intake suppression between age groups in response to naloxone and CCK-8.

Main Results:

• Naloxone did not significantly alter food intake differently between young and older adults overall, but showed increased suppression in older women.
• Intravenous CCK-8 infusion resulted in significantly greater suppression of food intake in older adults compared to younger adults (33.5% vs 15.5%).
• These findings suggest reduced stimulation by endogenous opioids in older women and maintained or increased sensitivity to CCK's satiating effects with age.

Conclusions:

• Ageing may involve altered sensitivity to appetite-regulating neurochemicals.
• Increased sensitivity to cholecystokinin (CCK) in older adults could contribute to reduced food intake.
• CCK antagonists may represent a potential therapeutic strategy to stimulate appetite and improve nutritional status in malnourished older individuals.