Phosphodiesterases: CNS Functions and Diseases

Steven J. Clapcote

People in modern, affluent societies are living longer but also becoming increasingly overweight. With increased life expectancy comes increased risk of developing age-related cognitive decline and neurodegenerative diseases, such that an increasing proportion of life may be lived with cognitive impairment as age increases. Obesity is associated with poorer cognitive function in elderly subjects, and often leads to ill-health arising from various complications such as metabolic syndrome and type-2 diabetes mellitus. This chapter provides an overview of the effects of administering pan-phosphodiesterase-4 (PDE4) inhibitors to animal models of cognitive ageing, Alzheimer's disease, frontotemporal dementia, fragile X syndrome, obesity and diabetes. Inhibition of the PDE4B subtype specifically is discussed as an approach to avoid the emetic side effects of pan-PDE4 inhibitors, whilst retaining their therapeutic effects. Finally, the findings of rodent studies that employ genetic and pharmacological approaches to specifically target PDE4B are discussed in relation to the potential utility of PDE4B-selective inhibitors for the treatment of cognitive impairment and obesity-related metabolic diseases.