Table 2.

Incident Dementia Rates by Birth Cohort and Age at Diagnosis

Birth Cohort	Age at Diagnosis, y
	<70	70–75	75–80	80–85	85–90	≥90	Total
1902–1911 (n = 308)
Cases	0	0	0	15	36	12	63
PY	0	0	328.04	850.69	591.17	182.55	1,952.46
Rate per 100 PY	0	0	0	1.763	6.090	6.574	3.227
1912–1921 (n = 1,170)
Cases	0	7	35	34	21	26	123
PY	663.53	2,684.76	3,233.16	1,561.3	663.6	618.74	9,425.1
Rate per 100 PY	0	0.261	1.083	2.178	3.165	4.202	1.305
1922–1931 (n = 931)
Cases	0	1	5	15	36	2	59
PY	500.9	548.36	1,031.21	2,015.22	1,563.51	227.44	5,886.65
Rate per 100 PY	0	0.182	0.485	0.744	2.303	0.879	1.000
1932–1941 (n = 601)
Cases	1	3	6	2	0	0	12
PY	588.19	1,740.84	1,391.4	281.5	0.15	0	4,002.08
Rate per 100 PY	0.170	0.172	0.431	0.710	0	0	0.300
Total (N = 3,010)
Cases	1	11	46	66	93	40	257
PY	1,752.62	4,973.96	5,983.82	4,708.72	2,818.43	1,028.73	21,266.3
Rate per 100 PY	0.057	0.221	0.769	1.402	3.300	3.889	1.208

Note: PY = person-years